Plant Nomenclature and ID

Lydiae claytonii

Horticulture Extension Agent

lclayton2@alaska.edu

Beginning Master Gardener Training – January 15, 2013

Plant systematics and taxonomy

Why classify?

History of plant classification systems

Some issues in plant systematics

How to use botanical nomenclature

Taxonomy -- the naming of groups (taxa, singular taxon)

Systematics -- a system for classifying organisms into groups

Why classify??

Goals of Classification

− Simplify − Communicate − Predict

How to classify plants?

Functional classifications Based on function or overall similarity

No assumption of evolutionary relationship

All cultures classify plants in ways meaningful to them

Examples of early plant classifications

2000 BC - Indian (Ayurvedic) texts described medicinal plants 1000-1700 AD - “Age of Herbals” in Europe

Functional classification systems

Carolus Linneaus (Systemae naturae, 1732)

- defined groups based on sexual characters

- developed binomial system of plant nomenclature

Engler, Bessey, Cronquist etc. (1800 - 1980s)

- sought to define evolutionary groups of plants

- published many regional floras (still in use)

Evolutionary classification systems

Evolutionary classification (includes both traditional systematics and modern phylogenetics)

1. Living species are related to one another by descent from common ancestors

2. Shared character states are clues to relatedness

Reasoning

What about convergent evolution?

Modern solution: Phylogenetic systematics Reconstructs relationships using lots of characters

Now, primarily uses DNA sequence data

From Nickrent et al.

• New evolutionary data

• Rediscovery of older names

• Lumpers vs. splitters

Agropyron spicatum Elymus spicatus Psuedoroegneria spicata Bluebunch wheatgrass

Why do plant names change?

Primates

(humans, great apes, old world monkeys, new world monkeys, lemurs)

Usually gene trees and older taxonomy agree . . . Monophyly (“one class”)

Named group shares an exclusive common ancestor

Polyphyly and Paraphyly

Named group is not an exclusive set of closest relatives

But sometimes named groups are not “natural”

“Marine mammals”

(sea lions, sea otters, whales)

cows dogs

Plant nomenclature in practice Species names (“scientific names”) are Latin binomials

Cornus florida L.

• Genus (pl. genera) • Always capitalized • Abbreviated on 2nd use

(C. florida)

• Authority • Specific epithet • Not capitalized • Often a descriptive adjective

Always underline or italicize species names (genus + specific epithet)

Why not just use common names?

1) Only scientific names are universal, used the same world-wide; e.g., Ipomoea -Woodbine, Morning Glory, Sweet potato

2) Common names are not consistent.

a) A taxon may have more than one common name.

b) One common name may refer to more than one taxon (e.g., ”hemlock”).

3) Common names tell nothing about rank.

4) Many, if not most, organisms have no common name in any language.

Why not just use common names?

What is rank?

Order -ales Cornales

Family -aceae Cornaceae

Subfamily -oideae Cornoideae

Genus (various) Cornus

Species (various) Cornus florida

Subspecies (various) Cornus florida ssp. urbiniana

Variety (various) Cornus florida var. rubra

trinomial

Rank at Family Level Identification at family level is easily done and often

very helpful in getting on the right track.

Example Cornaceae:

• Leaves simple, lacking stipules, and variously arranged, but commonly opposite or whorled.

• Inflorescence terminal, often composed of an umbel or corymb of small flowers subtended by showy, petaloid bracts.

• Perianth 4 or 5-merous; sepals represented by small teeth, fused, or entirely absent, petals small and inconspicuous.

• Stamens 4 or five. Inferior ovary of 2 or 3 fused carpels.

• Fruit a cluster of berries or drupes.

Learning binomial nomenclature

Syllabize and accent. Some guidelines:

1. Pronounce 1 syllable for every vowel Anemone = A-ne-mo-ne Cardamine = Car-da-mi-ne 2. But, pronounce proper names more-or-less normally Carex jonesii = Carex jones-ee-ee 3. Weird double consonants are usually silent Pseudotsuga = Su-do-(t)su-ga

Practice and review: oral and written recitation

Use mnemonic devices

• King Phillip Could Only Find Green Socks

Kingdom, Phylum, Class, Order, Family, Genus, Species

• Sedges have edges, rushes are round, grasses are hollow straight up from the ground!

Learn the etymology or meaning

Learning binomial nomenclature

Quaking Aspen, Populus tremuloides

(a great number; quaking)

Alaska Birch, Betula neoalaskana

(to shine; new)

Forsythia suspensa (named after William Forsythe; weeping)

Hybrids

One common cross is between Forsythia viridissima and Forsythia suspensa; this group has been given the grex name Fortyshia x intermedia, which includes most of the common.

Interspecific hybrid If you cross Platanus occidentalis, and Platanus orientalis… You get Platanus x acerifolia

Intergeneric hybrid If you cross Mahonia aquifolium with Berberis candidula… You get XMahoberberis aquicandidula

An unitalicized ‘x’ or ‘X’ indicating the cross

Downy brome/Cheatgrass, Bromus tectorum (oat-like; of roofs or houses)

Crabgrass, Digitaria sanguinalis (resembling a finger; bloody, blood red)

Field bindweed, Convolvulus arvensis (to twine around;

pertaining to cultivated fields)

Japanese knotweed, Polygonum cuspidatum

(many, swollen roots; sharp-pointed leaves)

Common lambsquarter, Chenopodium album (goose-footed, white)

Fireweed, Epilobium angustafolium (upon lobe- position of the petals above the ovary; narrow leaved)

Common chickweed, Stellaria media

(Starry; divide in the middle)

Black spruce, Picea mariana

(black in color; growing by or in the sea )

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