1.3: Introduction to Taxons

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Michelle Nakano
Kwantlen Polytechnic University via KPU Zero Textbook Cost Program

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Learning Objectives

Identify characteristics of taxons.

The plant family taxon is a grouping of plants consisting of one or more related genera that are more like each other than to other genera, and that includes the entire surviving lineage of the ancestral population. Family names always end with the suffix -aceae, except in a few notable cases where use of traditional names is also acceptable. Newer family names are based on the “type-genus” concept which means that for every family there is a genus that best represents the characteristics of the family. For example, Brassica (the cabbage genus) is the base for the family Brassicaceae, as is Rosa (the rose genus) for the family Rosaceae.

Older family names are still used since many are somewhat descriptive and may be more familiar than their newer counterparts. For example, Cruciferae (from the Latin crucifer, a cross) refers to the four-petal arrangement of flowers characteristic of the mustard family. The revised family names for some familiar plant groups are listed below.

Revised Family Names
Traditional Name	New Name	Common Name
Compositae	Asteraceae	Aster
Cruciferae	Brassicaceae	Mustard
Graminae	Poaceae	Grass
Labiatae	Lamiaceae	Mint
Leguminosae	Fabaceae	Pea
Umbelliferae	Apiaceae	Carrot

Because of technological advancements for determining plant genetics and other markers, some genera and family names have been reclassified under new names.

Reclassified Family Names
Family Name	Reclassified Name	Common Name
Aceraceae	Sapindaceae	Soapberry
Asclepiadaceae	Apocynaceae	Dogbane
Taxodiaceae	Cupressaceae	Cypress

Taxonomic Example

The list of ten Pacific Northwest native conifers can be grouped into three families. Within each family, there are a different number of genera, as represented by the common names. Within each genus, unless a monospecific (single) genus as with Taxus and Pseudotsuga, there are a number of different species.

Pinaceae – pine family

Douglas fir ( Pseudotsuga , 1 species)

hemlock (Tsuga, 2 species)

larch (Larix, 3 species)

true fir (Abies, 3 species)

spruce (Picea, 4 species)

pine (Pinus, 7 species)

Cupressaceae – cypress family

arborvitae (Thuja, 1 species)

yellow cedar (Cupressus, 1 species)

juniper (Juniperus, 3 species)

Taxaceae – yew family

yew (Taxus, 1 species)

Review

An interactive or media element has been excluded from this version of the text. You can view it online here:
kpu.pressbooks.pub/plant-identification/?p=160

An interactive or media element has been excluded from this version of the text. You can view it online here:
https://kpu.pressbooks.pub/plant-identification/?p=160