Plant Nomenclature and ID

Transcription

1 Beginning Master Gardener Training January 15, 2013 Plant Nomenclature and ID Lydiae claytonii Horticulture Extension Agent

2 Plant systematics and taxonomy Why classify? History of plant classification systems Some issues in plant systematics How to use botanical nomenclature

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4 Why classify?? Taxonomy -- the naming of groups (taxa, singular taxon) Systematics -- a system for classifying organisms into groups Goals of Classification Simplify Communicate Predict

5 How to classify plants?

6 Functional classifications Based on function or overall similarity No assumption of evolutionary relationship

7 Functional classification systems All cultures classify plants in ways meaningful to them Examples of early plant classifications 2000 BC - Indian (Ayurvedic) texts described medicinal plants AD - Age of Herbals in Europe

8 Evolutionary classification systems Carolus Linneaus (Systemae naturae, 1732) - defined groups based on sexual characters - developed binomial system of plant nomenclature Engler, Bessey, Cronquist etc. ( s) - sought to define evolutionary groups of plants - published many regional floras (still in use)

9 Evolutionary classification (includes both traditional systematics and modern phylogenetics) Reasoning 1. Living species are related to one another by descent from common ancestors 2. Shared character states are clues to relatedness What about convergent evolution?

10 Modern solution: Phylogenetic systematics Reconstructs relationships using lots of characters Now, primarily uses DNA sequence data From Nickrent et al.

11 Why do plant names change? New evolutionary data Rediscovery of older names Lumpers vs. splitters Agropyron spicatum Elymus spicatus Psuedoroegneria spicata Bluebunch wheatgrass

12 Usually gene trees and older taxonomy agree... Monophyly ( one class ) Named group shares an exclusive common ancestor Primates (humans, great apes, old world monkeys, new world monkeys, lemurs)

13 But sometimes named groups are not natural Polyphyly and Paraphyly Named group is not an exclusive set of closest relatives dogs Marine mammals (sea lions, sea otters, whales) cows

14 Plant nomenclature in practice Species names ( scientific names ) are Latin binomials Cornus florida L. Genus (pl. genera) Always capitalized Abbreviated on 2 nd use (C. florida) Specific epithet Authority Not capitalized Often a descriptive adjective Always underline or italicize species names (genus + specific epithet)

15 Why not just use common names?

16 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.

17 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 trinomial Variety (various) Cornus florida var. rubra

18 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.

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20 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

21 Learning binomial nomenclature 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

22 Quaking Aspen, Populus tremuloides (a great number; quaking)

23 Alaska Birch, Betula neoalaskana (to shine; new)

24 Forsythia suspensa (named after William Forsythe; weeping)

25 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

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

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

28 Field bindweed, Convolvulus arvensis (to twine around; pertaining to cultivated fields)

29 Japanese knotweed, Polygonum cuspidatum (many, swollen roots; sharp-pointed leaves)

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

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

32 Common chickweed, Stellaria media (Starry; divide in the middle)

33 Black spruce, Picea mariana (black in color; growing by or in the sea )

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