Introduction to Plant Taxonomy and Systematics Field Botany Introduction to Plant Taxonomy and Systematics

Reading assignments Judd et al.: Chapter 1, especially pages 1-5 (512-513 are merely examples – do not memorize!)

Definitions Systematics is synonymous with taxonomy, though the latter has a more old-fashioned connotation. The science of discovering, describing, and interpreting diversity among organisms. NOT just “naming,” although nomenclature is one part of it.

Systematics includes: Classification – Developing a logically organized scheme of categories and relationships, and placing organisms in it. Nomenclature – Naming the categories in the classification system, using standardized rules for efficient communication. Identification – Finding the name of an unknown organism, in relation to a pre-existing classification system.

Major groups of plants Green algae Not technically placed in the plant kingdom, but recent evidence clearly shows they are the closest relatives to it. Like the land plants, they have chlorophylls a & b and store energy as starch inside the chloroplast. Simple reproductive structures, external fertilization. We will not consider them further. All other plants are called “embryophytes.” Most live on land. Embryo fertilized and retained on the mother plant.

Major groups of embryophytes Non-vascular plants (bryophytes): No water-conducting xylem and phloem. Mosses, liverworts, hornworts Vascular, non-seed plants Ferns, clubmosses, spikemosses. Vascular, seed, non-flowering plants (Gymnosperms) Conifers, including pine Vascular, seed, flowering plants (Angiosperms) Most of the plants on earth!

Basics of nomenclature (more later!) Binomial nomenclature: Every species has a two-word name First word is genus (plural genera). Second word is specific epithet. The species is the 2-word combination. Often accompanied by the “authority” – the name of the person who gave this name to the species.

Standard form for binomials Genus name is always capitalized. Specific epithet is never capitalized. Specific epithet can never stand alone, though the genus name can be abbreviated to one letter. Genus name and specific epithet are italicized or underlined (separately) This applies to the genus name if used alone, too. Authority is not underlined or italicized. Standard abbreviations exist for some authorities.

Examples Quercus alba L. Pinus ponderosa Dougl. Quercus virginiana Mill. Ledum groenlandicum (Oeder) Kron & Judd How plants get their names will be discussed in later lectures.

The hierarchy of classification Groups within groups. Several* species together form a genus. Several* genera together form a family. Several* families together form an order. Several* orders together form a class. Several* classes together form a phylum. Several* phyla together form a kingdom. *but in some cases it might be only one.

Taxon The word taxon just means any named group, at any level, whether a species, family, class, or whatever. Plural is taxa.

Standard endings for taxa For a more complete list see p. 515. Genus does not have a standard ending. Family: -aceae Order: -ales Class: -opsida Phylum: -phyta Taxa above genus are capitalized, but not italicized or underlined

Exceptions to -aceae There are 8 large families for which the rules allow two names: modern and traditional. For the first 7 of these, you must know BOTH. Common name Traditional name Modern name Sunflower Compositae Asteraceae Mustard Cruciferae Brassicaceae Grass Gramineae Poaceae Mint Labiatae Lamiaceae Pea Leguminosae Fabaceae Carrot Umbelliferae Apiaceae Palm Palmae Arecaceae Clusia Guttiferae Clusiaceae