Plant Taxonomy

"plant" in the modern botanical sense (land plants): Use the current phylogenetic framework. Taxonomic rank = Division = Phylum. There are ~10 accepted phyla (Bryophyta, Marchantiophyta, Anthocerotophyta, Lycopodiophyta, Monilophyta, Cycadophyta, Ginkgophyta, Pinophyta, Gnetophyta, Magnoliophyta). A new organism would be placed within one of these, or if truly novel, it could require establishing a new phylum/division (very rare). Databases that use this: NCBI Taxonomy Catalogue of Life GBIF WFO (World Flora Online) International Code of Nomenclature for algae, fungi, and plants (ICN) defines things.

Traditional taxonomy typically relies on observable morphological characteristics (physical features), and may include divisions now considered to be more distantly related.

Modern classifications are built upon cladistics, which analyzes genetic and evolutionary relationships, resulting in several divisions replacing the traditional groupings. For example, the broad traditional category Bryophyta has been separated into three distinct divisions.

Kingdom (Regnum) – Plantae └── Division / Phylum (Divisio / Phylum) – e.g., Magnoliophyta └── Class (Classis) – e.g., Magnoliopsida └── Order (Ordo) – e.g., Rosales └── Family (Familia) – e.g., Rosaceae └── Subfamily (Subfamilia) – e.g., Rosoideae └── Tribe (Tribus) – e.g., Roseae └── Subtribe (Subtribus) – e.g., Rosinae └── Genus (Genus) – e.g., Rosa └── Species (Species) – e.g., Rosa canina └── Subspecies (Subspecies) – e.g., R. canina subsp. lutetiana └── Variety (Varietas) – e.g., R. canina var. andegavensis └── Subvariety (Subvarietas) └── Form (Forma) └── Subform (Subforma) Ranks under the modern botanical system Major ranks (required, in descending order) Kingdom – Plantae Division (Phylum) – modern botany uses Division traditionally, but Phylum is equally valid (both are treated as the same rank). Class Order Family Genus Species Those 7 are the core "mandatory" ranks in plant taxonomy. Intermediate ranks (commonly used, but optional) Subclass Superorder Subfamily Tribe Subtribe These are recognized in the Code, but are not always used for every lineage. Infraspecific ranks (below species, in descending order) Subspecies (subsp.) Variety (var.) Subvariety (subvar.) Form (f.) Subform (subf.) These are all valid under the ICN. The ICN specifies that you can use any one of them, but they must always appear below species, and their usage depends on the degree of variation you want to recognize.

Plant taxonomy uses a hierarchy of several major ranks, from the broadest categories down to the most specific.

The main taxonomic ranks for plants, from most inclusive to least inclusive, are:

• Domain: The highest rank, which for plants is Eukarya, as their cells contain a nucleus.
• Kingdom: The next highest rank; all plants are in the Kingdom Plantae.
• Division: Used in botany instead of the rank Phylum, which is used for animals.
• Class: A grouping of related plant orders.
• Order: A grouping of related plant families.
• Family: A grouping of related genera.
• Genus: A grouping of closely related species.
• Species: The most specific rank, representing a group of organisms that can interbreed.

Intermediate and informal ranks

To precisely classify the immense diversity of plant life, botanists also use numerous additional ranks. These intermediate ranks are typically formed by adding a prefix to the major rank's name.

Ranks above genus

• Subfamily (ending in "-oideae")
• Tribe (ending in "-eae")
• Subtribe (ending in "-inae")

Ranks below species
These ranks are used to denote groups within a species, often due to geographic isolation or minor differences in appearance.

• Subspecies (abbreviated subsp. or ssp.)
• Variety (abbreviated var.)
• Subvariety (abbreviated subvar.)
• Form (abbreviated f.)
• Subform (abbreviated subf.)

The Texas Bluebonnet (Lupinus texensis) is part of the legume or pea family (Fabaceae), which is the third largest family of flowering plants.

Its full taxonomic classification is as follows:

Major ranks

• Domain: Eukaryota
• Kingdom: Plantae (Plants)
• Division: Magnoliophyta (Flowering plants)
• Class: Magnoliopsida (Dicotyledons)
• Order: Fabales
• Family: Fabaceae (Pea family)
• Genus: Lupinus (Lupine)
• Species: L. texensis (Texas bluebonnet)

Intermediate ranks

For greater precision, botanists further subdivide the classification using intermediate ranks.

• Subfamily: Faboideae
• Tribe: Genisteae