document_title: Wikipedia:Citing sources

question_text: where does the isbn go in a citation

question_tokens: where does the isbn go in a citation

text: Wikipedia:Citing sources

text: Types of citation

text: WP:CITETYPE

text:
A full citation fully identifies a reliable source and, where applicable, the place in that source (such as a page number) where the information in question can be found. For example: Rawls, John. A Theory of Justice. Harvard University Press, 1971, p. 1. This type of citation is usually given as a footnote, and is the most commonly used citation method in Wikipedia articles.
An inline citation means any citation added close to the material it supports, for example after the sentence or paragraph, normally in the form of a footnote.
A short citation is an inline citation that identifies the place in a source where specific information can be found, but without giving full details of the source – these will have been provided in a full bibliographic citation either in an earlier footnote, or in a separate section. For example: Rawls 1971, p. 1. This system is used in some articles; the short citations may be given either as footnotes, or as parenthetical references within the text.
In-text attribution involves adding the source of a statement to the article text, such as Rawls argues that X.[5] This is done whenever a writer or speaker should be credited, such as with quotations, close paraphrasing, or statements of opinion or uncertain fact. The in-text attribution does not give full details of the source – this is done in a footnote in the normal way. See In-text attribution below.
A general reference is a citation that supports content, but is not linked to any particular piece of material in the article through an inline citation. General references are usually listed at the end of the article in a References section. They are usually found in underdeveloped articles, especially when all article content is supported by a single source. They may also be listed in more developed articles as a supplement to inline citations.

text: When and why to cite sources

text: WP:WHYCITE

text: By citing sources for Wikipedia content, you enable users to verify that the information given is supported by reliable sources, thus improving the credibility of Wikipedia while showing that the content is not original research. You also help users find additional information on the subject; and by giving attribution you avoid plagiarising the source of your words or ideas.

text: In particular, sources are required for material that is challenged or likely to be challenged – if reliable sources cannot be found for challenged material, it is likely to be removed from the article. Sources are also required when quoting someone, with or without quotation marks, or closely paraphrasing a source. However, the citing of sources is not limited to those situations – editors are always encouraged to add or improve citations for any information contained in an article.

text: Citations are especially desirable for statements about living persons, particularly when the statements are contentious or potentially defamatory. In accordance with the biography of living persons policy, unsourced information of this type is likely to be removed on sight.

text: Multimedia

text: For an image or other media file, details of its origin and copyright status should appear on its file page. Image captions should be referenced as appropriate just like any other part of the article. A citation is not needed for descriptions such as alt text that are verifiable directly from the image itself, or for text that merely identifies a source (e.g., the caption "Belshazzar's Feast (1635)" for File:Rembrandt-Belsazar.jpg).

text: When not to cite

text: WP:WHENNOTCITE

text: Citations are not used on disambiguation pages (sourcing for the information given there should be done in the target articles). Citations are often omitted from the lead section of an article, insofar as the lead summarizes information for which sources are given later in the article, although quotations and controversial statements, particularly if about living persons, should be supported by citations even in the lead. See WP:LEADCITE for more information.

text: Inline citations

text:
WP:INCITE
WP:INLINECITE

text: Inline citations allow the reader to associate a given bit of material in an article with the specific reliable source(s) that support it. Inline citations are added using either footnotes (long or short) or parenthetical references. This section describes how to add either type, and also describes how to create a list of full bibliography citations to support shortened footnotes or parenthetical references.

text: If long or short inline citations placed in footnotes are used, the first editor to add footnotes to an article must create a section where the list of those citations is to appear. This is not necessary for inline parenthetical references, as these appear directly inline in the article prose.

text: Footnotes

text: How to create the list of citations

text: This section, if needed, is usually titled "Notes" or "References", and is placed at or near the bottom of the article. For more about the order and titles of sections at the end of an article (which may also include "Further reading" and "External links" sections), see Wikipedia:Footers.

text: WP:ASL

text: With some exceptions discussed below, citations appear in a single section containing only the <references /> tag or the {{Reflist}} template. For example:

text: The footnotes will then automatically be listed under that section heading. Each numbered footnote marker in the text is a clickable link to the corresponding footnote, and each footnote contains a caret that links back to the corresponding point in the text. Scrolling lists, or lists of citations appearing within a scroll box, should never be used. This is because of issues with readability, browser compatibility, accessibility, printing, and site mirroring.[2]

text: If an article contains a list of general references, this is usually placed in a separate section, titled (for example) "References". This usually comes immediately after the section(s) listing footnotes, if any. (If the general references section is called "References", then the citations section is usually called "Notes".)

text: How to place an inline citation using ref tags

text: WP:CITEFOOT

text: To create a footnote, use the <ref>...</ref> syntax at the appropriate place in the article text, for example:

text: Justice is a human invention.<ref>Rawls, John. ''A Theory of Justice''. Harvard University Press, 1971, p. 1.</ref> It...

text: which will be displayed as something like:

text: Justice is a human invention.[1] It...

text: It will also be necessary to generate the list of footnotes (where the citation text is actually displayed); for this, see the previous section.

text: As in the above example, citation markers are normally placed after adjacent punctuation such as periods and commas. Citations should not be placed within, or on the same line as, section headings. For exceptions, see the Punctuation and footnotes section of the Manual of Style. Note also that no space is added before the citation marker.

text: The citation should be added close to the material it supports, offering text–source integrity. If a word or phrase is particularly contentious, an inline citation may be added next to that word or phrase within the sentence, but it is usually sufficient to add the citation to the end of the clause, sentence, or paragraph, so long as it's clear which source supports which part of the text.

text: Repeated citations

text: For multiple use of the same inline citation or footnote, you can use the named references feature, choosing a name to identify the inline citation, and typing <ref name="name">text of the citation</ref>. Thereafter, the same named reference may be reused any number of times either before or after the defining use by typing just <ref name="name" />. The use of the slash before the > means that the tag is self-closing, and the </ref> used to close other references must not be used in addition.

text: The text of the name can be almost anything—apart from being completely numeric. If spaces are used in the text of the name, the text must be placed within double quotes. Placing all named references within double quotes may be helpful to future editors who do not know that rule. To help with page maintenance, it is recommended that the text of the name have a connection to the inline citation or footnote, for example "author year page": <ref name="Smith 2005 p94">text of the citation</ref>.

text: Separating citations from explanatory footnotes

text: If an article contains both footnoted citations and other (explanatory) footnotes, then it is possible (but not necessary) to divide them into two separate lists, using the grouping feature described in the Grouping footnotes section of the footnotes help page. The explanatory footnotes and the citations are then placed in separate sections, called (for example) "Notes" and "References" respectively.

text: Avoiding clutter

text: Inline references can significantly bloat the wikitext in the edit window and can become difficult and confusing. There are two main methods to avoid clutter in the edit window:

text:
Inserting short citations (see below) that then refer to a full list of source texts

Parenthetical references (see below) are an established subformat of this, which forgoes the use of inline notes and simply puts the short citation in the main body.

Using list-defined references by collecting the full citation code within the reference list template, and then inserting them in the text with <ref name="ABC" /> tags.

text: As with other citation formats, articles should not undergo large-scale conversion between formats without consensus to do so.

text: Citing multiple pages of the same source

text: WP:IBID

text: When an article cites many different pages from the same source, to avoid the redundancy of many big, nearly identical full citations, most Wikipedia editors use one of three options:

text:
Short citations in footnotes
Named references in conjunction with the {{rp}} or {{r}} templates to specify the page
Short citations in parenthesis

text: The use of ibid. or Id. (or similar abbreviations) is discouraged, as these may become broken as new references are added (op. cit. is less problematic in that it should refer explicitly to a citation contained in the article; however, not all readers are familiar with the meaning of the terms). If the use of ibid is extensive, use the {{ibid}} template.

text: Duplicate citations

text: WP:DUPCITES

text: Please combine precisely duplicated full citations, in keeping with the existing citation style (if any). Do not discourage editors, particularly inexperienced ones, from adding duplicate citations when the use of the source is appropriate, because a duplicate is usually better than no citation. But any editor should feel free to combine them, and doing so is the best practice on Wikipedia.

text: Citations to different pages or parts of the same source can also be combined (preserving the distinct parts of the citations), as described in the previous section. Any method that is consistent with the existing citation style (if any) may be used, or consensus can be sought to change the existing style.

text: Short citations

text:
WP:CITESHORT
WP:SFN

text: Some Wikipedia articles use short citations, giving summary information about the source together with a page number, as in <ref>Smith 2010, p. 1.</ref>. These are used together with full citations, which give full details of the sources, but without page numbers, and are listed in a separate "References" section. Short citations are used in articles that apply parenthetical referencing (see below), but they can also be used as footnote citations, as described here.

text: Forms of short citations used include author-date referencing (APA style, Harvard style, or Chicago style), and author-title or author-page referencing (MLA style or Chicago style). As before, the list of footnotes is automatically generated in a "Notes" or "Footnotes" section, which immediately precedes the "References" section containing the full citations to the source. Short citations can be written manually, or by using the {{sfn}} or {{harvnb}} templates. (Note that templates should not be added without consensus to an article that already uses a consistent referencing style.) The short citations and full citations may be linked so that the reader can click on the short note to find full information about the source. See the template documentation for details and solutions to common problems. For variations with and without templates, see wikilinks to full references. For a set of realistic examples, see these.

text: This is how short citations look in the edit box:

text: This is how they look in the article:

text:
The Sun is pretty big,[1] but the Moon is not so big.[2] The Sun is also quite hot.[3]

Notes

text:
^ Miller 2005, p. 23.
^ Brown 2006, p. 46.
^ Miller 2005, p. 34.

tag: ol

text: References

text:
Brown, Rebecca (2006). "Size of the Moon", Scientific American, 51(78).
Miller, Edward (2005). The Sun. Academic Press.

text: Shortened notes using titles rather than publication dates would look like this in the article:

text: Notes

text:
^ Miller, The Sun, p. 23.
^ Brown, "Size of the Moon", p. 46.
^ Miller, The Sun, p. 34.

text: When using manual links it is easy to introduce errors such as duplicate anchors and unused references. The script User:Ucucha/HarvErrors will show many related errors. Duplicate anchors may be found by using the W3C Markup Validation Service.

text: Parenthetical referencing

text: While most articles use footnote citations as described in the above sections, some articles use a parenthetical referencing style. Here, short citations in parentheses, such as (Smith 2010, p. 1), are placed within the article text itself. Full details of each source used are given in a full citation, e.g., Smith, John. Name of Book. Cambridge University Press, 2010. The full citations are listed in alphabetical order, according to the authors' surnames, at the end of the article in a "References" section.

text: Several forms of short citation are used in Wikipedia; see Short citations above. The inline citation and full citation may be linked using a template (see linking inline and full citations); as with other citation templates, these should not be added to articles without consensus.

text: This is how it looks in the edit box:

text: This is how it looks in the article:

text:
The Sun is pretty big (Miller 2005, p. 1), but the Moon is not so big (Brown 2006, p. 2). The Sun is also quite hot (Miller 2005, p. 3).

References

text:
Brown, R (2006). "Size of the Moon", Scientific American, 51(78).
Miller, E (2005). The Sun, Academic Press.

text: Notice that, unlike footnotes, parenthetical references are placed before adjacent punctuation such as commas and periods.

text: What information to include

text:
WP:CITEHOW
WP:HOWCITE

text: Listed below is the information that a typical inline citation or general reference will provide, though other details may be added as necessary. This information is included in order to identify the source, assist readers in finding it, and (in the case of inline citations) indicate the place in the source where the information is to be found. (If an article uses parenthetical referencing or short citations, then the inline citations will refer to this information in abbreviated form, as described in the relevant sections above.)

text: Examples

text: Books

text: Citations for books typically include:

text:
name of author(s)
title of book in italics
translated title of book in square brackets after the title if not in English (optional)
volume when appropriate
name of publisher
city of publication, e.g. London: Routledge (optional)
year of publication of the edition you are citing
original year of publication in square brackets, e.g. 2017 [1972] (optional)
chapter or page numbers cited, if appropriate
edition, if not the first edition
ISBN (optional)

text:
name of author(s)
title of the chapter
translated title of the chapter book if not in English (optional)
name of book's editor
name of book and other details as above
chapter number or page numbers for the chapter (optional)

text: In some instances, the verso of a book may record, "Reprinted with corrections XXXX" or similar, where 'XXXX' is a year. This is a different version of a book in the same way that different editions are different versions. In such a case, record: the year of the particular reprint, the edition immediately prior to this particular reprint (if not the first edition) and a note to say "Reprint with corrections". If {{cite}} (or similar) is being used, the notation, "Reprint with corrections", can be added immediately following the template. Reprints of older publications gives an example of appending a similar textual note.

text: Journal articles

text: Citations for journal articles typically include:

text:
name of the author(s)
year and sometimes month of publication
title of the article within quotation marks
translated title of the article in square brackets after the title if not in English
name of the journal in italics
volume number, issue number, and page numbers (article numbers in some electronic journals)
DOI and/or other identifiers are optional

text: Newspaper articles

text: Citations for newspaper articles typically include:

text:
byline (author's name), if any
title of the article within quotation marks
translated title of the article in square brackets after the title if not in English
name of the newspaper in italics
city of publication (if not included in name of newspaper), in parentheses
date of publication (the "{{Cite news}}" template places the date after the byline if there is one)
page number(s) are optional

text: Web pages

text: WP:CITEWEB

text: Citations for World Wide Web pages typically include:

text:
URL of the web page – that is the URL of the web page where the referenced content can be found, not, e.g., the main page of a website when the content is on a subpage of that website (see Wikipedia:Shallow references)
name of the author(s)
title of the article within quotation marks
translated title of the article in square brackets after the title if not in English
title or domain name of the website
publisher, if known
date of publication
page number(s) (if applicable)
the date you retrieved (or accessed) the web page (required if the publication date is unknown)

text: Sound recordings

text: Citations for sound recordings typically include:

text:
name of the composer(s), songwriter(s), script writer(s) or the like
name of the performer(s)
title of the song or individual track in quotation marks
title of the album in italics (if applicable)
name of the record label
year of release
medium (for example: LP, audio cassette, CD, MP3 file)
approximate time at which event or point of interest occurs, where appropriate

text: Do not cite an entire body of work by one performer. Instead, make one citation for each work your text relies on.

text: Film, television, or video recordings

text: Citations for films, TV episodes, or video recordings typically include:

text:
name of the director
name of the producer, if relevant
names of major performers
for a TV episode, the title of the episode in quotation marks
title of the film or TV series in italics
name of the studio
year of release
medium (for example: film, videocassette, DVD)
approximate time at which event or point of interest occurs, where appropriate

text: Other

text: Identifying parts of a source

text:
WP:Page numbers
WP:PAGENUM

text: When citing lengthy sources, you should identify which part of a source is being cited.

text: Books and print articles

text: Specify the page number or range of page numbers. Page numbers are not required for a reference to the book or article as a whole. When you specify a page number, it is helpful to specify the version (date and edition for books) of the source because the layout, pagination, length, etc. can change between editions.

text: If there are no page numbers, whether in ebooks or print materials, then you can use other means of identifying the relevant section of a lengthy work, such as the chapter number or the section title.

text: In some works, such as plays and ancient works, there are standard methods of referring to sections, such as "Act 1, scene 2" for plays and Bekker numbers for Aristotle's works. Use these methods whenever appropriate.

text: Audio and video sources

text: Specify the time at which the event or other point of interest occurs. Be as precise as possible about the version of the source that you are citing; for example, movies are often released in different editions or "cuts". Due to variations between formats and playback equipment, precision may not be accurate in some cases. However, many government agencies do not publish minutes and transcripts but do post video of official meetings online; generally the subcontractors who handle audio-visual are quite precise.

text: Links and ID numbers

text: A citation ideally includes a link or ID number to help editors locate the source. If you have a URL (web page) link, you can add it to the title part of the citation, so that when you add the citation to Wikipedia the URL becomes hidden and the title becomes clickable. To do this, enclose the URL and the title in square brackets—the URL first, then a space, then the title. For example:

text: For web-only sources with no publication date, the "Retrieved" date (or the date you accessed the web page) should be included, in case the web page changes in the future. For example: Retrieved 15 July 2011 or you can use the accessdate parameter in the automatic Wikipedia:refToolbar 2.0 editing window feature.

text: You can also add an ID number to the end of a citation. The ID number might be an ISBN for a book, a DOI (digital object identifier) for an article, or any of several ID numbers that are specific to particular article databases, such as a PMID number for articles on PubMed. It may be possible to format these so that they are automatically activated and become clickable when added to Wikipedia, for example by typing ISBN (or PMID) followed by a space and the ID number.

text: If your source is not available online, it should be available in reputable libraries, archives, or collections. If a citation without an external link is challenged as unavailable, any of the following is sufficient to show the material to be reasonably available (though not necessarily reliable): providing an ISBN or OCLC number; linking to an established Wikipedia article about the source (the work, its author, or its publisher); or directly quoting the material on the talk page, briefly and in context.

text: Linking to pages in PDF files

text:
WP:PAGELINKS
WP:BOOKLINKS

text: Links to long PDF documents can be made more convenient by taking readers to a specific page with the addition of #page=n to the document URL, where n is the page number. For example, using http://www.domain.com/document.pdf#page=5 as the citation URL displays page five of the document in any PDF viewer that supports this feature. If the viewer or browser does not support it, it will display the first page instead.

text: Linking to Google Books pages

text: Google Books sometimes allows numbered book pages to be linked to directly. These can be added in several ways (with and without citation templates):

text:
Rawls, John. A Theory of Justice. Harvard University Press, 1971, p. 18.
Or with a template: Rawls, John (1971). A Theory of Justice. Harvard University Press. p. 18.
Rawls 1971, p. 18.
Rawls 1971, p. 18.
Rawls 1971, p. 18.
Rawls 1971, 18.

text: In edit mode, the URL for p. 18 of A Theory of Justice can be entered like this using the {{Cite book}} template:

text: or like this, in the first of the above examples, formatted manually:

text:
When the page number is a Roman numeral, commonly seen at the beginning of books, the URL looks like this for page xvii (Roman numeral 17) of the same book:
     https://books.google.com/books?id=kvpby7HtAe0C&pg=PR17
The &pg=PR17 indicates "page, Roman, 17", in contrast to the &pg=PA18, "page, Arabic, 18" the URL given earlier.

text:
You can also link to a tipped-in page, such as an unnumbered page of images between two regular pages. (If the page contains an image that is protected by copyright, it will be replaced by a tiny notice saying "copyrighted image".) The URL for eleventh tipped-in page inserted after page 304 of The Selected Papers of Elizabeth Cady Stanton and Susan B. Anthony, looks like this:
     https://books.google.com/books?id=dBs4CO1DsF4C&pg=PA304-IA11
The &pg=PA304-IA11 can be interpreted as "page, Arabic, 304; inserted after: 11".

text: Page links should only be added when the book is available for preview; they will not work with snippet view. Keep in mind that availability varies by location. No editor is required to add page links, but if another editor adds them, they should not be removed without cause; see the October 2010 RfC for further information.

text: There is a Wikipedia citation tool for Google Books that may be helpful.

text: Say where you read it

text:
WP:SAYWHEREYOUREADIT
WP:SAYWHEREYOUGOTIT
WP:SWYRT
WP:SWYGT
WP:SAYWHERE

text: "Say where you read it" follows the practice in academic writing of citing sources directly only if you have read the source yourself. If your knowledge of the source is secondhand—that is, if you have read Jones (2010), who cited Smith (2009), and you want to use what Smith (2009) said—make clear that your knowledge of Smith is based on your reading of Jones.

text: When citing the source, write the following (this formatting is just an example):

text: John Smith (2009). Name of Book I Haven't Seen, Cambridge University Press, p. 99, cited in Paul Jones (2010). Name of Encyclopedia I Have Seen, Oxford University Press, p. 29.

text: Or if you are using short citations:

text: Smith (2009), p. 99, cited in Jones (2010), p. 29.

text: Note: The advice to "say where you read it" does not mean that you have to give credit to any sources, search engines, websites, library catalogs, archives, etc., that led you to Smith's book. If you have read Smith's book yourself, that's all you have to cite. You do not need to specify how you obtained and read Smith's book.

text: So long as you are confident that you read a true and accurate copy, it does not matter whether you read the book using an online service like Google Books; using preview options at a bookseller's website like Amazon; on an e-reader (except to the extent that this affects page numbering); through your library; via online paid databases of scanned publications, such as JSTOR; using reading machines; or any other method.

text: Dates and reprints of older publications

text: Editors should be aware that older sources (especially those in the public domain) are sometimes reprinted with modern publication dates. When this occurs and the citation style being used requires it, cite both the original publication date, as well as the date of the re-publication. E.g.:

text: Darwin, Charles (1964) [1859]. On the Origin of Species (facsimile of 1st ed.). Harvard University Press.

text: This is done automatically in the {{citation}} and {{cite book}} templates when you use the |orig-year= parameter.

text: Alternately, information about the reprint can be appended as a textual note:

text: Boole, George (1854). An Investigation of the Laws of Thought on Which are Founded the Mathematical Theories of Logic and Probabilities. Macmillan.  Reprinted with corrections, Dover Publications, New York, NY, 1958.

text: Seasonal publication dates and differing calendar systems

text: Publication dates, for both older and recent sources, should be written with the goal of helping the reader find the publication and, once found, confirm that the correct publication has been located. For example, if the publication date bears a date in the Julian calendar, it should not be converted to the Gregorian calendar.

text: If the publication date was given as a season or holiday, such as "Winter" or "Christmas" of a particular year or two-year span, it should not be converted to a month or date, such as July–August or December 25. If a publication provided both seasonal and specific dates, prefer the specific one.

text: Additional annotation

text: In most cases it is sufficient for a citation footnote simply to identify the source (as described in the sections above); readers can then consult the source to see how it supports the information in the article. Sometimes, however, it is useful to include additional annotation in the footnote, for example to indicate precisely which information the source is supporting (particularly when a single footnote lists more than one source – see § Bundling citations and § Text–source integrity, below).

text: A footnote may also contain a relevant exact quotation from the source. This is especially helpful when the cited text is long or dense. A quotation allows readers to immediately identify the applicable portion of the reference. Quotes are also useful if the source is not easily accessible.

text: In the case of non-English sources, it may be helpful to quote from the original text and then give an English translation. If the article itself contains a translation of a quote from such a source (without the original), then the original should be included in the footnote. (See the WP:Verifiability § Non-English sources policy for more information.)

text: Citation style

text: WP:CITESTYLE

text: While citations should aim to provide the information listed above, Wikipedia does not have a single house style, though citations within any given article should follow a consistent style. A number of citation styles exist including those described in the Wikipedia articles for Citation, APA style, ASA style, MLA style, The Chicago Manual of Style, Author-date referencing, the Vancouver system and Bluebook.

text: Although nearly any consistent style may be used, avoid all-numeric date formats other than YYYY-MM-DD, because of the ambiguity concerning which number is the month and which the day. For example, 2002-06-11 may be used, but not 11/06/2002. The YYYY-MM-DD format should in any case be limited to Gregorian calendar dates where the year is after 1582.

text: Variation in citation methods

text: WP:CITEVAR

text: Editors should not attempt to change an article's established citation style merely on the grounds of personal preference, to make it match other articles, or without first seeking consensus for the change. The arbitration committee ruled in 2006:

text: Wikipedia does not mandate styles in many different areas; these include (but are not limited to) American vs. British spelling, date formats, and citation style. Where Wikipedia does not mandate a specific style, editors should not attempt to convert Wikipedia to their own preferred style, nor should they edit articles for the sole purpose of converting them to their preferred style, or removing examples of, or references to, styles which they dislike.

text: As with spelling differences, it is normal practice to defer to the style used by the first major contributor or adopted by the consensus of editors already working on the page, unless a change in consensus has been achieved. If the article you are editing is already using a particular citation style, you should follow it; if you believe it is inappropriate for the needs of the article, seek consensus for a change on the talk page. If you are the first contributor to add citations to an article, you may choose whichever style you think best for the article.

text: If all or most of the citations in an article consist of bare URLs, or otherwise fail to provide needed bibliographic data – such as the name of the source, the title of the article or web page consulted, the author (if known), the publication date (if known), and the page numbers (where relevant) – then that would not count as a "consistent citation style" and can be changed freely to insert such data. The data provided should be sufficient to uniquely identify the source, allow readers to find it, and allow readers to initially evaluate it without retrieving it.

text: To be avoided

text: When an article is already consistent, avoid:

text:
switching between major citation styles, e.g. parenthetical and <ref> tags, or replacing the preferred style of one academic discipline with another's;
adding citation templates to an article that already uses a consistent system without templates, or removing citation templates from an article that uses them consistently;
changing where the references are defined, e.g. moving reference definitions in the reflist to the prose, or moving reference definitions from the prose into the reflist.

text: Generally considered helpful

text: The following are standard practice:

text:
improving existing citations by adding missing information, such as by replacing bare URLs with full bibliographic citations: an improvement because it aids verifiability, and fights linkrot;
replacing some or all general references with inline citations: an improvement because it provides more verifiable information to the reader, and helps maintain text–source integrity;
imposing one style on an article with inconsistent citation styles (e.g., some of the citations in footnotes and others as parenthetical references): an improvement because it makes the citations easier to understand and edit;
fixing errors in citation coding, including incorrectly used template parameters, and <ref> markup problems: an improvement because it helps the citations to be parsed correctly;
combining duplicate citations (see § Duplicate citations, above).

text: Handling links in citations

text: As noted above under What information to include, it is helpful to include hyperlinks to source material, when available. Here we note some issues concerning these links.

text: Avoid embedded links

text: Embedded links to external websites should not be used as a form of inline citation, because they are highly susceptible to linkrot. Wikipedia allowed this in its early years—for example by adding a link after a sentence, like this [http://media.guardian.co.uk/site/story/0,14173,1601858,00.html], which looks like this. [1] This is no longer recommended. Raw links are not recommended in lieu of properly written out citations, even if placed between ref tags, like this <ref>[http://media.guardian.co.uk/site/story/0,14173,1601858,00.html]</ref>. Since any citation that accurately identifies the source is better than none, do not revert the good-faith addition of partial citations. They should be considered temporary, and replaced with more complete, properly formatted citations as soon as possible.

text: Embedded links should never be used to place external links in the content of an article, like this: "Apple, Inc. announced their latest product...".

text: Convenience links

text: A convenience link is a link to a copy of your source on a web page provided by someone other than the original publisher or author. For example, a copy of a newspaper article no longer available on the newspaper's website may be hosted elsewhere. When offering convenience links, it is important to be reasonably certain that the convenience copy is a true copy of the original, without any changes or inappropriate commentary, and that it does not infringe the original publisher's copyright. Accuracy can be assumed when the hosting website appears reliable. Where several sites host a copy of the material, the site selected as the convenience link should be the one whose general content appears most in line with Wikipedia:Neutral point of view and Wikipedia:Verifiability.

text: Indicating availability

text: WP:INDICATEAVAIL

text: Links to sources

text: WP:SOURCELINKS

text: For a source available in hardcopy, microform, and/or online, omit, in most cases, which one you read. While it is useful to cite author, title, edition (1st, 2nd, etc.), and similar information, it generally is not important to cite a database such as ProQuest, EbscoHost, or JStor (see the list of academic databases and search engines) or to link to such a database requiring a subscription or a third party's login. The basic bibliographic information you provide should be enough to search for the source in any of these databases that have the source. Don't add a URL that has a part of a password embedded in the URL. However, you may provide the DOI, ISBN, or another uniform identifier, if available. If the publisher offers a link to the source or its abstract that does not require a payment or a third party's login for access, you may provide the URL for that link. If the source only exists online, give the link even if access is restricted (see WP:PAYWALL).

text: Preventing and repairing dead links

text: WP:DEADREF

text: To help prevent dead links, persistent identifiers are available for some sources. Some journal articles have a digital object identifier (DOI); some online newspapers and blogs, and also Wikipedia, have permalinks that are stable. When permanent links aren't available, consider archiving the referenced document when writing the article; on-demand web archiving services such as WebCite (http://www.webcitation.org) or the Wayback Machine (http://www.archive.org/web) are fairly easy to use (see pre-emptive archiving).

text: Dead links should be repaired or replaced if possible. Do not delete a citation merely because the URL is not working. Follow these steps when you encounter a dead URL being used as a reliable source to support article content:

text:
Confirm status: First, check the link to confirm that it is dead and not temporarily down. Search the website to see whether it has been rearranged. The online service "Is it down right now?" can help to determine if a site is down, and any information known.
Check for a changed URL on the same Web site: Pages are frequently moved to different location on the same site as they become archive content rather than news. The site's error page may have a "Search" box; alternatively, in the popular Google search engine the keyterm "site:" is used, as in ⟨site:en.wikipedia.org "New Zealand police vehicle markings and livery"⟩.
Check for web archives: Many Web archiving services exist; link to their archive of the URL's content, if available. Examples:

Internet Archive has billions of archived web pages. See Wikipedia:Using the Wayback Machine.
WebCite has billions of archived web pages. See Wikipedia:Using WebCite.
The UK Government Web Archive (http://www.nationalarchives.gov.uk/webarchive/) preserves 1500 UK central government websites.
The Mementos interface allows you to search multiple archiving services with a single request using the Memento protocol. Unfortunately, the Mementos web page interface removes any parameters which are passed with the URL. If the URL contains a "?" it is unlikely to work properly. When entering the URL into the Mementos interface manually, the most common change needed is to change "?" to "%3F". While making only this change will not be sufficient in all cases, it will work most of the time. The bookmarklet in the table below will properly encode URLs such that searches will work.

text:
Remove convenience links: If the material was published on paper (e.g., academic journal, newspaper article, magazine, book), then the dead URL is not necessary. Simply remove the dead URL, leaving the remainder of the reference intact.
Find a replacement source: Search the web for quoted text, the article title, and parts of the URL. Consider contacting the website/person that originally published the reference and asking them to republish it. Ask other editors for help finding the reference somewhere else, including the user who added the reference. Find a different source that says essentially the same thing as the reference in question.
Remove hopelessly lost web-only sources: If the source material does not exist offline, and if there is no archived version of the web page (be sure to wait ~24 months), and if you cannot find another copy of the material, then the dead citation should be removed and the material it supports should be regarded as unverified if there is no other supporting citation. If it is material that is specifically required by policy to have an inline citation, then please consider tagging it with {{citation needed}}. It may be appropriate for you to move the citation to the talk page with an explanation, and notify the editor who added the now-dead link.

text: Text–source integrity

text: WP:INTEGRITY

text: When using inline citations, it is important to maintain text–source integrity. The point of an inline citation is to allow readers and other editors to check that the material is sourced; that point is lost if the citation is not clearly placed. The distance between material and its source is a matter of editorial judgment, but adding text without clearly placing its source may lead to allegations of original research, of violations of the sourcing policy, and even of plagiarism.

text: Editors should exercise caution when rearranging or inserting material to ensure that text–source relationships are maintained. References need not be moved solely to maintain the chronological order of footnotes as they appear in the article, and should not be moved if doing so might break the text-source relationship.

text: If a sentence or paragraph is footnoted with a source, adding new material that is not supported by the existing source to the sentence/paragraph, without a source for the new text, is highly misleading if placed to appear that the cited source supports it. When new text is inserted into a paragraph, make sure it is supported by the existing or a new source. For example, when editing text originally reading

text:
The sun is pretty big.[1]

Notes

text: ^ Miller, Edward. The Sun. Academic Press, 2005, p. 1.

text: an edit that does not imply that the new material is sourced by the same reference is

text:
The sun is pretty big.[1] The sun is also quite hot.[2]

Notes

text:
^ Miller, Edward. The Sun. Academic Press, 2005, p. 1.
^ Smith, John. The Sun's Heat. Academic Press, 2005, p. 2.

text: Do not add other facts or assertions into a fully cited paragraph or sentence:

text: N

text:
The sun is pretty big, but the moon is not so big.[1] The sun is also quite hot.[2]

Notes

text: Include a source to support the new information. There are several ways to write this, including:

text: Y

text:
The sun is pretty big,[1] but the moon is not so big.[2] The sun is also quite hot.[3]

Notes

text:
^ Miller, Edward. The Sun. Academic Press, 2005, p. 1.
^ Brown, Rebecca. "Size of the Moon", Scientific American, 51(78):46.
^ Smith, John. The Sun's Heat. Academic Press, 2005, p. 2.

text: Bundling citations

text:
WP:CITEBUNDLE
WP:BUNDLING

text: Sometimes the article is more readable if multiple citations are bundled into a single footnote. For example, when there are multiple sources for a given sentence, and each source applies to the entire sentence, the sources can be placed at the end of the sentence, like this.[4][5][6][7] Or they can be bundled into one footnote at the end of the sentence or paragraph, like this.[4]

text: Bundling is also useful if the sources each support a different portion of the preceding text, or if the sources all support the same text. Bundling has several advantages:

text:
It helps readers and other editors see at a glance which source supports which point, maintaining text–source integrity;
It avoids the visual clutter of multiple clickable footnotes inside a sentence or paragraph;
It avoids the confusion of having multiple sources listed separately after sentences, with no indication of which source to check for each part of the text, such as this.[1][2][3][4]
It makes it less likely that inline citations will be moved inadvertently when text is re-arranged, because the footnote states clearly which source supports which point.

text: When formatting multiple citations in a footnote, there are several layouts available, as illustrated below. Within a given article, only a single layout should be used.

text:
The sun is pretty big, but the moon is not so big. The sun is also quite hot.[1]

Notes

text:
Bullets
^ For the sun's size, see Miller, Edward. The Sun. Academic Press, 2005, p. 1.

For the moon's size, see Brown, Rebecca. "Size of the Moon", Scientific American, 51(78):46.
For the sun's heat, see Smith, John. The Sun's Heat. Academic Press, 2005, p. 2.

Line breaks
^ For the sun's size, see Miller, Edward. The Sun. Academic Press, 2005, p. 1.
For the moon's size, see Brown, Rebecca. "Size of the Moon", Scientific American, 51(78):46.
For the sun's heat, see Smith, John. The Sun's Heat. Academic Press, 2005, p. 2.
Paragraph

^ For the sun's size, see Miller, Edward. The Sun. Academic Press, 2005, p. 1. For the moon's size, see Brown, Rebecca. "Size of the Moon", Scientific American, 51(78):46. For the sun's heat, see Smith, John. The Sun's Heat. Academic Press, 2005, p. 2.

text: In-text attribution

text: WP:INTEXT

text: In-text attribution is the attribution inside a sentence of material to its source, in addition to an inline citation after the sentence. In-text attribution should be used with direct speech (a source's words between quotation marks or as a block quotation); indirect speech (a source's words modified without quotation marks); and close paraphrasing. It can also be used when loosely summarizing a source's position in your own words. It avoids inadvertent plagiarism and helps the reader see where a position is coming from. An inline citation should follow the attribution, usually at the end of the sentence or paragraph in question.

text: For example:

text: N To reach fair decisions, parties must consider matters as if behind a veil of ignorance.[2]

text: Y John Rawls says that, to reach fair decisions, parties must consider matters as if behind a veil of ignorance.[2]

text: When using in-text attribution, make sure it doesn't lead to an inadvertent neutrality violation. For example, the following implies parity between the sources, without making clear that the position of Darwin is the majority view:

text: N Charles Darwin says that human beings evolved through natural selection, but John Smith writes that we arrived here in pods from Mars.

text: Y Humans evolved through natural selection, as first explained in Charles Darwin's The Descent of Man, and Selection in Relation to Sex.

text: Neutrality issues apart, there are other ways in-text attribution can mislead. The sentence below suggests The New York Times has alone made this important discovery:

text: N According to The New York Times, the sun will set in the west this evening.

text: Y The sun sets in the west each evening.

text: It is preferable not to clutter articles with information best left to the references. Interested readers can click on the ref to find out the publishing journal:

text: N In an article published in The Lancet in 2012, researchers announced the discovery of the new tissue type.[3]

text: Y The discovery of the new tissue type was first published by researchers in 2012.[3]

text: Simple facts such as this can have inline citations to reliable sources as an aid to the reader, but normally the text itself is best left as a plain statement without in-text attribution:

text: Y By mass, oxygen is the third most abundant element in the universe after hydrogen and helium.[4]

text: General references

text: WP:GENREF

text: A general reference is a citation to a reliable source that supports content, but is not linked to any particular text in the article through an inline citation. General references are usually listed at the end of the article in a "References" section, and are usually sorted by the last name of the author or the editor. General reference sections are most likely to be found in underdeveloped articles, especially when all article content is supported by a single source. The disadvantage of general references is that text–source integrity is lost, unless the article is very short. They are frequently reworked by later editors into inline citations.

text: The appearance of a general references section is the same as those given above in the sections on short citations and parenthetical references. If both cited and uncited references exist, their distinction can be highlighted with separate section names, e.g., "References" and "General references".

text: Dealing with unsourced material

text:
WP:NOCITE
WP:BLPCITE

text: If an article has no references at all, then:

text:
If the entire article is "Patent Nonsense", tag it for speedy deletion using criterion G1.
If the article is a biography of a living person, it can be tagged with {{subst:prod blp}} to propose deletion. If it's a biography of a living person and is an attack page, then it should be tagged for speedy deletion using criterion G10, which will blank the page.
If the article doesn't fit into the above two categories, then consider finding references yourself, or commenting on the article talk page or the talk page of the article creator. You may also tag the article with the {{unreferenced}} template and consider nominating it for deletion.

text: For individual unreferenced claims in an article:

text:
If the article is a biography of a living person, then any contentious material must be removed immediately: see Biographies of living persons. If the unreferenced material is seriously inappropriate, it may need to be hidden from general view, in which case request admin assistance.
If the material added appears to be false or an expression of opinion, remove it and inform the editor who added the unsourced material. The {{uw-unsourced1}} template may be placed on their talk page.
In any other case consider finding references yourself, or commenting on the article talk page or the talk page of the editor who added the unsourced material. You may place a {{citation needed}} or {{dubious}} tag against the added text.

text: Citation templates and tools

text: WP:CITECONSENSUS

text: Citation templates can be used to format citations in a consistent way. The use of citation templates is neither encouraged nor discouraged: an article should not be switched between templated and non-templated citations without good reason and consensus – see Variation in citation methods above.

text: If citation templates are used in an article, the parameters should be accurate. It is inappropriate to set parameters to false values to cause the template to render as if it were written in some style other than the style normally produced by the template (e.g., MLA style).

text: Metadata

text: Citations may be accompanied by metadata, though it is not mandatory. Most citation templates on Wikipedia use the COinS standard. Metadata such as this allow browser plugins and other automated software to make citation data accessible to the user, for instance by providing links to their library's online copies of the cited works. In articles that format citations manually, metadata may be added manually in a span, according to the COinS specification.

text: Citation processing tools

text:
User:Ark25/RefScript, a JavaScript bookmarklet – creates references in one click, works for many newspapers
User:Badgettrg, Biomedical citation maker. uses Pubmed ID (PMID) or DOI or PMCID or NCT. Adds links to ACP Journal Club and Evidence-Based Medicine comments if present.
User:Citation bot (formerly DOI bot) – a bot that automatically fixes common errors in individual citations and adds missing fields
User:Zhaofeng Li/Reflinks – adds titles to bare url references and other cleanup
Citation template generator – generates complete templates using identification numbers such as PMIDs (PubMed IDs).
Wikipedia template filling – generates Vancouver style citations from PMIDs (PubMed IDs).
Wikipedia citation tool for Google Books – converts bare Google book links into {{cite book}} format.
DOI Wikipedia reference generator
New York Times Wikipedia reference generator
Yadkard: A web-based tool for generating shortened footnotes and citation using Google Books URLs, DOI or ISBN. Also supports some news websites.
User:Salix alba/Citoid a client for the mw:citoid server which generates Citation Style 1 templates from urls.
Template:Ref info, which can aid evaluating what kind of citation style was used to write the article

text: Programming tools

text:
Wikicite is a free program that helps editors to create citations for their Wikipedia contributions using citation templates. It is written in Visual Basic .NET, making it suitable only for users with the .NET Framework installed on Windows, or, for other platforms, the Mono alternative framework. Wikicite and its source code is freely available; see the developer's page for further details.

Wikicite+ is a program based on the original Wikicite source code. It features extra validation, bug fixes, additional cite templates (such as cite episode) as well as tools for stub sorting and more. It is also available for free under the Apache License 2.0 and is open source.

User:Richiez has tools to automatically handle citations for a whole article at a time. Converts occurrences of {{pmid XXXX}} or {{isbn XXXX}} to properly formatted footnote or Harvard-style references. Written in Ruby and requires a working installation with basic libraries.
pubmed2wikipedia.xsl an XSL stylesheet transforming the XML output of PubMed to Wikipedia refs.
RefTag by Apoc2400 creates a prefilled {{cite book}} template with various options from a Google Books URL. The page provides a bookmarklet for single-click transfer.
wikiciter web interface, does Google Books, pdf files, beta.

text: Citation export tools

text: You can insert a link beside each citation in Wikipedia, allowing you to export the citation to a reference manager such as EndNote. To install the script just add the following line to Special:MyPage/skin.js (applies to the currently selected skin) or Special:MyPage/common.js (applies to all skins)"

text: Then "Publish changes" and follow the instructions at the top of that page to bypass your browser's cache.

text: Reference management software

text: Reference management software can output formatted citations in several styles, including BibTeX, RIS, or Wikipedia citation template styles.


document_title: Ascomycota

question_text: the asexual spores produced by members of the phylum ascomycota are called

question_tokens: the asexual spores produced by members of the phylum ascomycota are called

root

text: Ascomycota

text: Asexual reproduction in ascomycetes and their characteristics[edit]

text: Ascomycetes:

tag: p

text: Ascomycetes are 'spore shooters'. They are fungi which produce microscopic spores inside special, elongated cells or sacs, known as 'asci', which give the group its name.

text: Asexual reproduction:

text: Asexual reproduction is the dominant form of propagation in the Ascomycota, and is responsible for the rapid spread of these fungi into new areas. Asexual reproduction of ascomycetes is very diverse from both structural and functional points of view. The most important and general is production of conidia, but chlamydospores are also frequently produced. Furthermore, Ascomycota also reproduce asexually through budding.

text: 1) Conidia formation:

text: Asexual reproduction may occur through vegetative reproductive spores, the conidia. Asexual, non-motile haploid spore of a fungus, which is named after the Greek word for dust; conia and hence also known as conidiospores and mitospores. The conidiospores commonly contain one nucleus and are products of mitotic cell divisions and thus are sometimes call mitospores, which are genetically identical to the mycelium from which they originate. They are typically formed at the ends of specialized hyphae, the conidiophores. Depending on the species they may be dispersed by wind or water, or by animals. Conidiophores may simply branch off from the mycelia or they may be formed in fruiting bodies.

text: The hypha that creates the sporing (conidiating) tip can be very similar to the normal hyphal tip, or it can be differentiated. The most common differentiation is the formation of a bottle shaped cell called a phialide, from which the spores are produced. As all of these asexual structures are not single hyphae. In some groups, the conidiophores (the structures that bear the conidia) are aggregated to form a thick structure.

text: E.g. In the order Moniliales, all of them are single hyphae with the exception of the aggregations, termed as coremia or synnema. These produce structures rather like corn-stokes, with many conidia being produced in a mass from the aggregated conidiophores.

text: The diverse conidia and conidiophores sometimes develop in asexual sporocarps with different characteristics (e.g. aecervulus, pycnidium, sporodochium). Some species of Ascomycetes form their structures within plant tissue, either as parasite or saprophytes. These fungi have evolved more complex asexual sporing structures, probably influenced by the cultural conditions of plant tissue as a substrate. These structures are called the sporodochium. This is a cushion of conidiophores created from a pseudoparenchymatous stroma in plant tissue. The pycnidium is a globose to flask-shaped parenchymatous structure, lined on its inner wall with conidiophores. The acervulus is a flat saucer shaped bed of conidiophores produced under a plant cuticle, which eventually erupt through the cuticle for dispersal.

text: 2) Budding:

text: Asexual reproduction process in ascomycetes also involves the budding which we clearly observe in yeast. This is termed a “blastic process”. It involves the blowing out or blebbing of the hyphal tip wall. The blastic process can involve all wall layers, or there can be a new cell wall synthesized which is extruded from within the old wall.

text: The initial events of budding can be seen as the development of a ring of chitin around the point where the bud is about to appear. This reinforces and stabilizes the cell wall. Enzymatic activity and turgor pressure act to weaken and extrude the cell wall. New cell wall material is incorporated during this phase. Cell contents are forced into the progeny cell, and as the final phase of mitosis ends a cell plate, the point at which a new cell wall will grow inwards from, forms.

text: Characteristics of ascomycetes:

text: · Ascomycota are morphologically diverse. The group includes organisms from unicellular yeasts to complex cup fungi.

text: · There are 2000 identified genera and 30,000 species of Ascomycota.

text: · The unifying characteristic among these diverse groups is the presence of a reproductive structure known as the ascus, though in some cases it has a reduced role in the life cycle.

text: · Many ascomycetes are of commercial importance. Some play a beneficial role, such as the yeasts used in baking, brewing, and wine fermentation, plus truffles and morels, which are held as gourmet delicacies.

text: · Many of them cause tree diseases, such as Dutch elm disease and apple blights.

text: · Some of the plant pathogenic ascomycetes are apple scab, rice blast, the ergot fungi, black knot, and the powdery mildews.

text: · The yeasts are used to produce alcoholic beverages and breads. The mold Penicillium is used to produce the anti-biotic penicillin.

text: · Almost half of all members of the phylum Ascomycota form symbiotic associations with algae to form lichens.

text: · Others, such as morels (a highly prized edible fungi), form important mychorrhizal relationships with plants, thereby providing enhanced water and nutrient uptake and, in some cases, protection from insects.

text: · Almost all ascomycetes are terrestrial or parasitic. However, a few have adapted to marine or freshwater environments.

text: · The cell walls of the hyphae are variably composed of chitin and β-glucans, just as in Basidiomycota. However, these fibers are set in a matrix of glycoprotein containing the sugars galactose and mannose.

text: · The mycelium of ascomycetes is usually made up of septate hyphae. However, there is not necessarily any fixed number of nuclei in each of the divisions.

text: · The septal walls have septal pores which provide cytoplasmic continuity throughout the individual hyphae. Under appropriate conditions, nuclei may also migrate between septal compartments through the septal pores.

text: · A unique character of the Ascomycota (but not present in all ascomycetes) is the presence of Woronin bodies on each side of the septa separating the hyphal segments which control the septal pores. If an adjoining hypha is ruptured, the Woronin bodies block the pores to prevent loss of cytoplasm into the ruptured compartment. The Woronin bodies are spherical, hexagonal, or rectangular membrane bound structures with a crystalline protein matrix.

text: Modern classification of Ascomycota[edit]

text: There are three subphyla that are described and accepted:

text:
The Pezizomycotina are the largest subphylum and contains all ascomycetes that produce ascocarps (fruiting bodies), except for one genus, Neolecta, in the Taphrinomycotina. It is roughly equivalent to the previous taxon, Euascomycetes. The Pezizomycotina includes most macroscopic "ascos" such as truffles, ergot, ascolichens, cup fungi (discomycetes), pyrenomycetes, lorchels, and caterpillar fungus.[1] It also contains microscopic fungi such as powdery mildews, dermatophytic fungi, and Laboulbeniales.
The Saccharomycotina comprise most of the "true" yeasts, such as baker's yeast and Candida, which are single-celled (unicellular) fungi, which reproduce vegetatively by budding. Most of these species were previously classified in a taxon called Hemiascomycetes.
The Taphrinomycotina include a disparate and basal group within the Ascomycota that was recognized following molecular (DNA) analyses. The taxon was originally named Archiascomycetes (or Archaeascomycetes). It includes both hyphal fungi (Neolecta, Taphrina, Archaeorhizomyces), fission yeasts (Schizosaccharomyces), and the mammalian lung parasite, Pneumocystis.

tag: ul

text: Outdated taxon names[edit]

text: Several outdated taxon names—based on morphological features—are still occasionally used for species of the Ascomycota. These include the following sexual (teleomorphic) groups, defined by the structures of their sexual fruiting bodies: the Discomycetes, which included all species forming apothecia; the Pyrenomycetes, which included all sac fungi that formed perithecia or pseudothecia, or any structure resembling these morphological structures; and the Plectomycetes, which included those species that form cleistothecia. Hemiascomycetes included the yeasts and yeast-like fungi that have now been placed into the Saccharomycotina or Taphrinomycotina, while the Euascomycetes included the remaining species of the Ascomycota, which are now in the Pezizomycotina, and the Neolecta, which are in the Taphrinomycotina.

text: Some ascomycetes do not reproduce sexually or are not known to produce asci and are therefore anamorphic species. Those anamorphs that produce conidia (mitospores) were previously described as Mitosporic Ascomycota. Some taxonomists placed this group into a separate artificial phylum, the Deuteromycota (or "Fungi Imperfecti"). Where recent molecular analyses have identified close relationships with ascus-bearing taxa, anamorphic species have been grouped into the Ascomycota, despite the absence of the defining ascus. Sexual and asexual isolates of the same species commonly carry different binomial species names, as, for example, Aspergillus nidulans and Emericella nidulans, for asexual and sexual isolates, respectively, of the same species.

text: Species of the Deuteromycota were classified as Coelomycetes if they produced their conidia in minute flask- or saucer-shaped conidiomata, known technically as pycnidia and acervuli.[5] The Hyphomycetes were those species where the conidiophores (i.e., the hyphal structures that carry conidia-forming cells at the end) are free or loosely organized. They are mostly isolated but sometimes also appear as bundles of cells aligned in parallel (described as synnematal) or as cushion-shaped masses (described as sporodochial).[6]

text: Morphology[edit]

text: Most species grow as filamentous, microscopic structures called hyphae or as budding single cells (yeasts). Many interconnected hyphae form a thallus usually referred to as the mycelium, which—when visible to the naked eye (macroscopic)—is commonly called mold. During sexual reproduction, many Ascomycota typically produce large numbers of asci. The ascus is often contained in a multicellular, occasionally readily visible fruiting structure, the ascocarp (also called an ascoma). Ascocarps come in a very large variety of shapes: cup-shaped, club-shaped, potato-like, spongy, seed-like, oozing and pimple-like, coral-like, nit-like, golf-ball-shaped, perforated tennis ball-like, cushion-shaped, plated and feathered in miniature (Laboulbeniales), microscopic classic Greek shield-shaped, stalked or sessile. They can appear solitary or clustered. Their texture can likewise be very variable, including fleshy, like charcoal (carbonaceous), leathery, rubbery, gelatinous, slimy, powdery, or cob-web-like. Ascocarps come in multiple colors such as red, orange, yellow, brown, black, or, more rarely, green or blue. Some ascomyceous fungi, such as Saccharomyces cerevisiae, grow as single-celled yeasts, which—during sexual reproduction—develop into an ascus, and do not form fruiting bodies.

text: In lichenized species, the thallus of the fungus defines the shape of the symbiotic colony. Some dimorphic species, such as Candida albicans, can switch between growth as single cells and as filamentous, multicellular hyphae. Other species are pleomorphic, exhibiting asexual (anamorphic) as well as a sexual (teleomorphic) growth forms.

text: Except for lichens, the non-reproductive (vegetative) mycelium of most ascomycetes is usually inconspicuous because it is commonly embedded in the substrate, such as soil, or grows on or inside a living host, and only the ascoma may be seen when fruiting. Pigmentation, such as melanin in hyphal walls, along with prolific growth on surfaces can result in visible mold colonies; examples include Cladosporium species, which form black spots on bathroom caulking and other moist areas. Many ascomycetes cause food spoilage, and, therefore, the pellicles or moldy layers that develop on jams, juices, and other foods are the mycelia of these species or occasionally Mucoromycotina and almost never Basidiomycota. Sooty molds that develop on plants, especially in the tropics are the thalli of many species.[clarification needed]

text: Large masses of yeast cells, asci or ascus-like cells, or conidia can also form macroscopic structures. For example. Pneumocystis species can colonize lung cavities (visible in x-rays), causing a form of pneumonia.[7] Asci of Ascosphaera fill honey bee larvae and pupae causing mummification with a chalk-like appearance, hence the name "chalkbrood".[8] Yeasts for small colonies in vitro and in vivo, and excessive growth of Candida species in the mouth or vagina causes "thrush", a form of candidiasis.

text: The cell walls of the ascomycetes almost always contain chitin and β-glucans, and divisions within the hyphae, called "septa", are the internal boundaries of individual cells (or compartments). The cell wall and septa give stability and rigidity to the hyphae and may prevent loss of cytoplasm in case of local damage to cell wall and cell membrane. The septa commonly have a small opening in the center, which functions as a cytoplasmic connection between adjacent cells, also sometimes allowing cell-to-cell movement of nuclei within a hypha. Vegetative hyphae of most ascomycetes contain only one nucleus per cell (uninucleate hyphae), but multinucleate cells—especially in the apical regions of growing hyphae—can also be present.

text: Metabolism[edit]

text: In common with other fungal phyla, the Ascomycota are heterotrophic organisms that require organic compounds as energy sources. These are obtained by feeding on a variety of organic substrates including dead matter, foodstuffs, or as symbionts in or on other living organisms. To obtain these nutrients from their surroundings, ascomycetous fungi secrete powerful digestive enzymes that break down organic substances into smaller molecules, which are then taken up into the cell. Many species live on dead plant material such as leaves, twigs, or logs. Several species colonize plants, animals, or other fungi as parasites or mutualistic symbionts and derive all their metabolic energy in form of nutrients from the tissues of their hosts.

text: Owing to their long evolutionary history, the Ascomycota have evolved the capacity to break down almost every organic substance. Unlike most organisms, they are able to use their own enzymes to digest plant biopolymers such as cellulose or lignin. Collagen, an abundant structural protein in animals, and keratin—a protein that forms hair and nails—, can also serve as food sources. Unusual examples include Aureobasidium pullulans, which feeds on wall paint, and the kerosene fungus Amorphotheca resinae, which feeds on aircraft fuel (causing occasional problems for the airline industry), and may sometimes block fuel pipes.[9] Other species can resist high osmotic stress and grow, for example, on salted fish, and a few ascomycetes are aquatic.

text: The Ascomycota is characterized by a high degree of specialization; for instance, certain species of Laboulbeniales attack only one particular leg of one particular insect species. Many Ascomycota engage in symbiotic relationships such as in lichens—symbiotic associations with green algae or cyanobacteria—in which the fungal symbiont directly obtains products of photosynthesis. In common with many basidiomycetes and Glomeromycota, some ascomycetes form symbioses with plants by colonizing the roots to form mycorrhizal associations. The Ascomycota also represents several carnivorous fungi, which have developed hyphal traps to capture small protists such as amoebae, as well as roundworms (Nematoda), rotifers, tardigrades, and small arthropods such as springtails (Collembola).

text: Distribution and living environment[edit]

text: The Ascomycota are represented in all land ecosystems worldwide, occurring on all continents including Antarctica.[10] Spores and hyphal fragments are dispersed through the atmosphere and freshwater environments, as well as ocean beaches and tidal zones. The distribution of species is variable; while some are found on all continents, others, as for example the white truffle Tuber magnatum, only occur in isolated locations in Italy and Eastern Europe.[11] The distribution of plant-parasitic species is often restricted by host distributions; for example, Cyttaria is only found on Nothofagus (Southern Beech) in the Southern Hemisphere.

text: Reproduction[edit]

text: Asexual reproduction[edit]

text: Asexual reproduction is the dominant form of propagation in the Ascomycota, and is responsible for the rapid spread of these fungi into new areas. It occurs through vegetative reproductive spores, the conidia. The conidiospores commonly contain one nucleus and are products of mitotic cell divisions and thus are sometimes called mitospores, which are genetically identical to the mycelium from which they originate. They are typically formed at the ends of specialized hyphae, the conidiophores. Depending on the species they may be dispersed by wind or water, or by animals.

text: Asexual spores[edit]

text: Different types of asexual spores can be identified by colour, shape, and how they are released as individual spores. Spore types can be used as taxonomic characters in the classification within the Ascomycota. The most frequent types are the single-celled spores, which are designated amerospores. If the spore is divided into two by a cross-wall (septum), it is called a didymospore.

text:
Conidiospores of Trichoderma aggressivum, Diameter approx. 3µm

Conidiophores of molds of the genus Aspergillus, conidiogenesis is blastic-phialidic

Conidiophores of Trichoderma harzianum, conidiogenesis is blastic-phialidic

Conidiophores of Trichoderma fertile with vase-shaped phialides and newly formed conidia on their ends (bright points)

tag: table

text: When there are two or more cross-walls, the classification depends on spore shape. If the septae are transversal, like the rungs of a ladder, it is a phragmospore, and if they possess a net-like structure it is a dictyospore. In staurospores ray-like arms radiate from a central body; in others (helicospores) the entire spore is wound up in a spiral like a spring. Very long worm-like spores with a length-to-diameter ratio of more than 15:1, are called scolecospores.

text: Conidiogenesis and dehiscence[edit]

text: Important characteristics of the anamorphs of the Ascomycota are conidiogenesis, which includes spore formation and dehiscence (separation from the parent structure). Conidiogenesis corresponds to Embryology in animals and plants and can be divided into two fundamental forms of development: blastic conidiogenesis, where the spore is already evident before it separates from the conidiogenic hypha, and thallic conidiogenesis, during which a cross-wall forms and the newly created cell develops into a spore. The spores may or may not be generated in a large-scale specialized structure that helps to spread them.

text: These two basic types can be further classified as follows:

text:
blastic-acropetal (repeated budding at the tip of the conidiogenic hypha, so that a chain of spores is formed with the youngest spores at the tip),
blastic-synchronous (simultaneous spore formation from a central cell, sometimes with secondary acropetal chains forming from the initial spores),
blastic-sympodial (repeated sideways spore formation from behind the leading spore, so that the oldest spore is at the main tip),
blastic-annellidic (each spore separates and leaves a ring-shaped scar inside the scar left by the previous spore),
blastic-phialidic (the spores arise and are ejected from the open ends of special conidiogenic cells called phialides, which remain constant in length),
basauxic (where a chain of conidia, in successively younger stages of development, is emitted from the mother cell),
blastic-retrogressive (spores separate by formation of crosswalls near the tip of the conidiogenic hypha, which thus becomes progressively shorter),
thallic-arthric (double cell walls split the conidiogenic hypha into cells that develop into short, cylindrical spores called arthroconidia; sometimes every second cell dies off, leaving the arthroconidia free),
thallic-solitary (a large bulging cell separates from the conidiogenic hypha, forms internal walls, and develops to a phragmospore).

text: Sometimes the conidia are produced in structures visible to the naked eye, which help to distribute the spores. These structures are called "conidiomata" (singular: conidioma), and may take the form of pycnidia (which are flask-shaped and arise in the fungal tissue) or acervuli (which are cushion-shaped and arise in host tissue).[12]

text: Dehiscence happens in two ways. In schizolytic dehiscence, a double-dividing wall with a central lamella (layer) forms between the cells; the central layer then breaks down thereby releasing the spores. In rhexolytic dehiscence, the cell wall that joins the spores on the outside degenerates and releases the conidia.

text: Heterokaryosis and parasexuality[edit]

text: Several Ascomycota species are not known to have a sexual cycle. Such asexual species may be able to undergo genetic recombination between individuals by processes involving heterokaryosis and parasexual events.

text: Parasexuality refers to the process of heterokaryosis, caused by merging of two hyphae belonging to different individuals, by a process called anastomosis, followed by a series of events resulting in genetically different cell nuclei in the mycelium.[13] The merging of nuclei is not followed by meiotic events, such as gamete formation and results in an increased number of chromosomes per nuclei. Mitotic crossover may enable recombination, i.e., an exchange of genetic material between homologous chromosomes. The chromosome number may then be restored to its haploid state by nuclear division, with each daughter nuclei being genetically different from the original parent nuclei.[14] Alternatively, nuclei may lose some chromosomes, resulting in aneuploid cells. Candida albicans (class Saccharomycetes) is an example of a fungus that has a parasexual cycle (see Candida albicans and Parasexual cycle).

text: Sexual reproduction[edit]

text: Sexual reproduction in the Ascomycota leads to the formation of the ascus, the structure that defines this fungal group and distinguishes it from other fungal phyla. The ascus is a tube-shaped vessel, a meiosporangium, which contains the sexual spores produced by meiosis and which are called ascospores.

text: Apart from a few exceptions, such as Candida albicans, most ascomycetes are haploid, i.e., they contain one set of chromosomes per nucleus. During sexual reproduction there is a diploid phase, which commonly is very short, and meiosis restores the haploid state. The sexual cycle of one well-studied representative species of Ascomycota is described in greater detail in Neurospora crassa.

text: Formation of sexual spores[edit]

text: The sexual part of the life cycle commences when two hyphal structures mate. In the case of homothallic species, mating is enabled between hyphae of the same fungal clone, whereas in heterothallic species, the two hyphae must originate from fungal clones that differ genetically, i.e., those that are of a different mating type. Mating types are typical of the fungi and correspond roughly to the sexes in plants and animals; however one species may have more than two mating types, resulting in sometimes complex vegetative incompatibility systems. The adaptive function of mating type is discussed in Neurospora crassa.

text: Gametangia are sexual structures formed from hyphae, and are the generative cells. A very fine hypha, called trichogyne emerges from one gametangium, the ascogonium, and merges with a gametangium (the antheridium) of the other fungal isolate. The nuclei in the antheridium then migrate into the ascogonium, and plasmogamy—the mixing of the cytoplasm—occurs. Unlike in animals and plants, plasmogamy is not immediately followed by the merging of the nuclei (called karyogamy). Instead, the nuclei from the two hyphae form pairs, initiating the dikaryophase of the sexual cycle, during which time the pairs of nuclei synchronously divide. Fusion of the paired nuclei leads to mixing of the genetic material and recombination and is followed by meiosis. A similar sexual cycle is present in the blue green algae (Rhodophyta). A discarded hypothesis held that a second karyogamy event occurred in the ascogonium prior to ascogeny, resulting in a tetraploid nucleus which divided into four diploid nuclei by meiosis and then into eight haploid nuclei by a supposed process called brachymeiosis, but this hypothesis was disproven in the 1950s.[15]

text: From the fertilized ascogonium, dinucleate hyphae emerge in which each cell contains two nuclei. These hyphae are called ascogenous or fertile hyphae. They are supported by the vegetative mycelium containing uni– (or mono–) nucleate hyphae, which are sterile. The mycelium containing both sterile and fertile hyphae may grow into fruiting body, the ascocarp, which may contain millions of fertile hyphae.

text: The sexual structures are formed in the fruiting layer of the ascocarp, the hymenium. At one end of ascogenous hyphae, characteristic U-shaped hooks develop, which curve back opposite to the growth direction of the hyphae. The two nuclei contained in the apical part of each hypha divide in such a way that the threads of their mitotic spindles run parallel, creating two pairs of genetically different nuclei. One daughter nucleus migrates close to the hook, while the other daughter nucleus locates to the basal part of the hypha. The formation of two parallel cross-walls then divides the hypha into three sections: one at the hook with one nucleus, one at the basal of the original hypha that contains one nucleus, and one that separates the U-shaped part, which contains the other two nuclei.

text: Fusion of the nuclei (karyogamy) takes place in the U-shaped cells in the hymenium, and results in the formation of a diploid zygote. The zygote grows into the ascus, an elongated tube-shaped or cylinder-shaped capsule. Meiosis then gives rise to four haploid nuclei, usually followed by a further mitotic division that results in eight nuclei in each ascus. The nuclei along with some cytoplasma become enclosed within membranes and a cell wall to give rise to ascospores that are aligned inside the ascus like peas in a pod. (For a general description of meiosis and its adaptive function see Meiosis and Bernstein and Bernstein[16]).

text: Upon opening of the ascus, ascospores may be dispersed by the wind, while in some cases the spores are forcibly ejected form the ascus; certain species have evolved spore cannons, which can eject ascospores up to 30 cm. away. When the spores reach a suitable substrate, they germinate, form new hyphae, which restarts the fungal life cycle.

text: The form of the ascus is important for classification and is divided into four basic types: unitunicate-operculate, unitunicate-inoperculate, bitunicate, or prototunicate. See the article on asci for further details.

text: Ecology[edit]

text: The Ascomycota fulfil a central role in most land-based ecosystems. They are important decomposers, breaking down organic materials, such as dead leaves and animals, and helping the detritivores (animals that feed on decomposing material) to obtain their nutrients. Ascomycetes along with other fungi can break down large molecules such as cellulose or lignin, and thus have important roles in nutrient cycling such as the carbon cycle.

text: The fruiting bodies of the Ascomycota provide food for many animals ranging from insects and slugs and snails (Gastropoda) to rodents and larger mammals such as deer and wild boars.

text: Many ascomycetes also form symbiotic relationships with other organisms, including plants and animals.

text: Lichens[edit]

text: Probably since early in their evolutionary history, the Ascomycota have formed symbiotic associations with green algae (Chlorophyta), and other types of algae and cyanobacteria. These mutualistic associations are commonly known as lichens, and can grow and persist in terrestrial regions of the earth that are inhospitable to other organisms and characterized by extremes in temperature and humidity, including the Arctic, the Antarctic, deserts, and mountaintops. While the photoautotrophic algal partner generates metabolic energy through photosynthesis, the fungus offers a stable, supportive matrix and protects cells from radiation and dehydration. Around 42% of the Ascomycota (about 18,000 species) form lichens, and almost all the fungal partners of lichens belong to the Ascomycota.

text: Mycorrhizal fungi and endophytes[edit]

text: Members of the Ascomycota form two important types of relationship with plants: as mycorrhizal fungi and as endophytes. Mycorrhiza are symbiotic associations of fungi with the root systems of the plants, which can be of vital importance for growth and persistence for the plant. The fine mycelial network of the fungus enables the increased uptake of mineral salts that occur at low levels in the soil. In return, the plant provides the fungus with metabolic energy in the form of photosynthetic products.

text: Endophytic fungi live inside plants, and those that form mutualistic or commensal associations with their host, do not damage their hosts. The exact nature of the relationship between endophytic fungus and host depends on the species involved, and in some cases fungal colonization of plants can bestow a higher resistance against insects, roundworms (nematodes), and bacteria; in the case of grass endophytes the fungal symbiont produces poisonous alkaloids, which can affect the health of plant-eating (herbivorous) mammals and deter or kill insect herbivores.[17]

text: Symbiotic relationships with animals[edit]

text: Several ascomycetes of the genus Xylaria colonize the nests of leafcutter ants and other fungus-growing ants of the tribe Attini, and the fungal gardens of termites (Isoptera). Since they do not generate fruiting bodies until the insects have left the nests, it is suspected that, as confirmed in several cases of Basidiomycota species, they may be cultivated.[clarification needed]

text: Bark beetles (family Scolytidae) are important symbiotic partners of ascomycetes. The female beetles transport fungal spores to new hosts in characteristic tucks in their skin, the mycetangia. The beetle tunnels into the wood and into large chambers in which they lay their eggs. Spores released from the mycetangia germinate into hyphae, which can break down the wood. The beetle larvae then feed on the fungal mycelium, and, on reaching maturity, carry new spores with them to renew the cycle of infection. A well-known example of this is Dutch elm disease, caused by Ophiostoma ulmi, which is carried by the European elm bark beetle, Scolytus multistriatus.[18]

text: Importance for humans[edit]

text: Ascomycetes make many contributions to the good of humanity, and also have many ill effects.

text: Harmful interactions[edit]

text: One of their most harmful roles is as the agent of many plant diseases. For instance:

text: Dutch Elm Disease, caused by the closely related species Ophiostoma ulmi and Ophiostoma novo-ulmi, has led to the death of many elms in Europe and North America.

text:
The originally Asian Cryphonectria parasitica is responsible for attacking Sweet Chestnuts (Castanea sativa), and virtually eliminated the once-widespread American Chestnut (Castanea dentata),
A disease of maize (Zea mays), which is especially prevalent in North America, is brought about by Cochliobolus heterostrophus.
Taphrina deformans causes leaf curl of peach.
Uncinula necator is responsible for the disease powdery mildew, which attacks grapevines.
Species of Monilinia cause brown rot of stone fruit such as peaches (Prunus persica) and sour cherries (Prunus ceranus).
Members of the Ascomycota such as Stachybotrys chartarum are responsible for fading of woollen textiles, which is a common problem especially in the tropics.
Blue-green, red and brown molds attack and spoil foodstuffs - for instance Penicillium italicum rots oranges.
Cereals infected with Fusarium graminearum contain mycotoxins like deoxynivalenol (DON), which can lead to skin and mucous membrane lesions when eaten by pigs.
Ergot (Claviceps purpurea) is a direct menace to humans when it attacks wheat or rye and produces highly poisonous and carcinogenic alkaloids, causing ergotism if consumed. Symptoms include hallucinations, stomach cramp, and a burning sensation in the limbs ("Saint Anthony's Fire").
Aspergillus flavus, which grows on peanuts and other hosts, generates aflatoxin, which damages the liver and is highly carcinogenic.
Candida albicans, a yeast that attacks the mucous membranes, can cause an infection of the mouth or vagina called thrush or candidiasis, and is also blamed for "yeast allergies".
Fungi like Epidermophyton cause skin infections but are not very dangerous for people with healthy immune systems. However, if the immune system is damaged they can be life-threatening; for instance, Pneumocystis jirovecii is responsible for severe lung infections that occur in AIDS patients.

text: Positive effects[edit]

text: On the other hand, ascus fungi have brought some important benefits to humanity.

text:
The most famous case may be that of the mould Penicillium chrysogenum (formerly Penicillium notatum), which, probably to attack competing bacteria, produces an antibiotic that, under the name of penicillin, triggered a revolution in the treatment of bacterial infectious diseases in the 20th century.
The medical importance of Tolypocladium niveum as an immunosuppressor can hardly be exaggerated. It excretes Ciclosporin, which, as well as being given during Organ transplantation to prevent rejection, is also prescribed for auto-immune diseases such as multiple sclerosis, although there is some doubt over the long-term side-effects of the treatment.

text:
Some ascomycete fungi can be altered relatively easily through genetic engineering procedures. They can then produce useful proteins such as insulin, human growth hormone, or TPa, which is employed to dissolve blood clots.
Several species are common model organisms in biology, including Saccharomyces cerevisiae, Schizosaccharomyces pombe, and Neurospora crassa. The genomes of a number of ascomycete fungi have been fully sequenced.
Baker's Yeast (Saccharomyces cerevisiae) is used to make bread, beer and wine, during which process sugars such as glucose or sucrose are fermented to make ethanol and carbon dioxide. Bakers use the yeast for carbon dioxide production, causing the bread to rise, with the ethanol boiling off during cooking. Most vintners use it for ethanol production, with the carbon dioxide being released into the atmosphere during fermentation. Brewers and traditional producers of sparkling wine use both, with a primary fermentation for the alcohol and a secondary one to produce the carbon dioxide bubbles that provide the drinks with "sparkling" texture in the case of wine and the desirable foam in the case of beer.
Enzymes of Penicillium camemberti play a role in the manufacture of the cheeses Camembert and Brie, while those of Penicillium roqueforti do the same for Gorgonzola, Roquefort and Stilton.
In Asia, Aspergillus oryzae is added to a pulp of soaked soya beans to make soy sauce, and is used to break down starch in rice and other grains into simple sugars for fermentation into East Asian alcoholic beverages such as huangjiu and sake.
Finally, some members of the Ascomycota are choice edibles; morels (Morchella spp.), truffles (Tuber spp.), and lobster mushroom (Hypomyces lactifluorum) are some of the most sought-after fungal delicacies.