Wikipedia:WikiProject Plants/Categorization

Non-monotypic taxa
Summary: categorize an article at the highest taxonomic rank which yields a "sensible" set of category sizes (say 10-100 entries).

, an article is categorized under the appropriate taxon in its taxonomic hierarchy. Consider species Y z in family Xaceae in order Wales.
 * The article about species Y z is placed in "Category:Y", i.e. the category for its genus, using the wikitext to ensure its correct alphabetic placement in the category under the specific epithet. "Category:Y" will itself be placed in "Category:Xaceae".
 * The article about genus Y is also placed in "Category:Y" using the wikitext to ensure that it comes first in the list of articles in the category.
 * The article about family Xaceae is placed in "Category:Xaceae", using the wikitext to ensure that it comes first in the list of articles in the category. "Category:Xaceae" is itself placed in "Category:Wales".
 * Above the level of orders, the main APG clades are used, as in taxoboxes.

Thus the "ideal" categorization can be represented as in Figure 1.

The problem is that categories should be of a reasonable size to make navigation easier for readers, i.e. requiring the minimum amount of searching in a list and clicking through multiple pages. Neither very large categories nor very small ones are desirable.
 * Categories which run over several screens (say more than 50-100 entries) should be split up (diffused); this may require the use of categories for minor taxonomic ranks, such as sections or subfamilies.
 * More commonly, small categories should be combined, so that, for example, species are categorized under the family or order or even a higher taxonomic rank.

Thus, the categorization shown in Figure 2 is used for the article Cabomba aquatica.

Monotypic taxa
Summary: categorize as appropriate to the rank, including categorizing redirects.

When taxa are monotypic, a single article has to cover more than one rank. (Thus Amborella covers the family Amborellaceae, the genus Amborella and the species Amborella tricopoda.) There will be redirects from the ranks not used as the article title. Categorize each of the redirects and the article appropriately for its rank. Thus, among other categories:
 * The redirect Amborellaceae is put in Category:Angiosperm families
 * The article Amborella is put in Category:Angiosperm genera
 * The redirect Amborella trichopoda is put in Category:Plants described in 1869.

Taxonomic rank categories
There is a, parallel categorization hierarchy for plant articles about particular ranks in the taxonomic hierarchy. this system of categorization was less complete than the main taxonomic category system for plants. In principle, there are three main hierarchies – for genera, families and orders.

Consider the genus Y in the family Xaceae in the order Wales in the clade V. In the ideal system: This produces the ideal categorization by rank shown in Figure 3.
 * The article on genus Y is placed in "Category:Xaceae genera", which is itself placed in "Category:Wales genera" (and so on upwards). This is to placing the article in "Category:Y" or other appropriately sized taxonomic category.
 * The article on family Xaceae is placed in "Category:Wales families", which is itself placed a category for the families of the appropriate higher clade.
 * The article on order Wales is placed in "Category:V orders", which is itself placed in a category for the orders of the appropriate higher taxon.

As with the main taxonomic categories, in practice this system has to be modified to ensure reasonable category sizes, so that, for example, an article on a genus may be placed in the category for the genera of its order rather than the genera of its family.

Since, for example, "Category:Xaceae genera" is a member of "Category:Xaceae", the two categorization systems (one by taxon and the other by taxon rank) interact. Figure 4 shows this for an idealized categorization. In actual use, most of the links will have been created already, since they connect categories, so all that an editor normally has to do is to categorize an article about a plant species, genus, family or order.

The template Plant taxa category is used to produce a standard header for taxonomic rank categories.

Historically recognized plant taxa
Articles about plant taxa not used in current classification systems should be placed in one of the categories of the "historically recognized plant taxa" hierarchy shown in the figure below. The term "historically recognized" is preferred to "obsolete".

Such articles, which do not have taxoboxes, should not be placed in a normal "parent taxa" category. Thus the article Celastraceae, about a family recognized in APG III, is categorized as Category:Rosid families. The article Parnassiaceae, a family sunk into Celastraceae in APG III, is categorized as Category:Historically recognized angiosperm families and as a rosid family.


 * Articles about angiosperms should be placed in one of the four "angiosperm" categories.
 * Those articles which clearly and unambiguously relate to orders, families or genera should be placed in Category:Historically recognized angiosperm orders, Category:Historically recognized angiosperm families or Category:Historically recognized angiosperm genera. Orders will almost always have names ending in "-ales", families in "-aceae". Examples:
 * Bromeliales can only be used an order, given the ending, so is placed in Category:Historically recognized angiosperm orders.
 * Myrsinaceae (not recognized in APG III) can only be a family, given the ending, so is placed in Category:Historically recognized angiosperm families.
 * Orobus is a genus no longer used (and cannot be a name for a higher rank) so is placed in Category:Historically recognized angiosperm genera.
 * Articles about taxa with names which can be used at different levels according to the ICN or that were not historically used for orders, families or genera should be placed in Category:Historically recognized angiosperm taxa.
 * Helobiae was an order, but the name is not unambiguously reserved for this rank, so is categorized at Category:Historically recognized angiosperm taxa.
 * Galearieae is a tribal name that is no longer used; as it's not an order, family or genus it is categorized at Category:Historically recognized angiosperm taxa.
 * Articles about other groups of plants (e.g. bryophytes, pteridophytes, gymnosperms) should be placed in one of the four "historically recognized plant" categories, using the same logic as above to decide which of the four to use. Examples:
 * Taxodiaceae was used for a gymnosperm family (as shown by the ending), so is categorized at Category:Historically recognized plant families.
 * Cryptogamae is an alternative name for one of Linnaeus's "classes", so it's categorized at Category:Historically recognized plant taxa. (Note that it's the by this scientific name which is categorized, not the article Cryptogam, which is titled by a common name.)