In this course, three taxonomic categories feature prominently: family, genus, and species. Genera (plural of genus) are kinds of plants. Many genera are well-known, such as the different cereals and grasses, i.e. members of the family Poaceae: barley (Hordeum), oats (Avena), rye (Secale), wheat (Triticum), rice (Oryza), corn (Zea), wild rice (Zizania), sugar cane (Saccharum), bluegrass (Poa), or crabgrass (Digitaria). Note how the names of genera are capitalized. Note also how italics are used for the names of genera and for those of the taxa included within them (species and sub-specific taxa; these names are not capitalized). Species are particular kinds of plants; click on the link to find out more about this taxonomic category. Note too that the generic names above were explained by reference to English common names (barley, oats rye, wheat, rice, etc.) as these were thought to be familiar to most readers of this web page.
Members of a genus (i.e. species) typically share many morphological, chemical, or anatomical features that set them apart from other genera in the family. These shared, derived features ("synapomorphies") are often seen as evidence that members of a genus share a single common ancestor, and so are monophyletic.
The complete names of plant taxa include identification of the authority responsible for the name, or for the combination in which it appears. Click here to learn more about authorities. Each name of a genus is also associated with a type species; consult a textbook on plant taxonomy in order to learn more about the type method as practiced by botanical systematists. The standard form for the names of plant taxa can be accessed on the International Plant Names Index (IPNI) web site.
Click on the FNA logo to access the article by Stebbins (1993) on concepts of species and genera: .
| What are plant families? | How do we distinguish them? | How and why do we study them? | Selected vascular plant families of Ontario | Reading List | Course outline |
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