Taxonomy,Classification,

and Identification

Alayne Fronimos

Department of Biological SciencesAlamo Community Colleges

Taxonomy

= the study of naming, describing and classifying organisms, including the

rules, theories, principles and procedures

Taxon = a group of organisms recognized at any level of a taxonomical hierarchy

(e. g. Family, Class)

Classification

= the orderly arrangement of organisms into a hierarchal system that is derived from an

accumulation of information about the individual organisms, the end result

expressing an interrelationship

Why?

Because it provides humans with a means to address organisms and their relationships to

one another

Because it allows humans to make inferences about unfamiliar organisms

Because it is in our nature

Classification

Systems:

Artificial = based on obvious or convenient items of information called characters (e.g. flower color, locality).

Natural = based on morphological features that give the sense of correlation with those of another organism. (e.g. trees, grasses)

Phylogenetic = based on the proposed lineage derived from a wide variety of information.

Aristotle

Greek Philosopher

First to propose a system of classification

Scala Naturalae

Two types of animals:• With blood• Without blood

Theophrastus

Greek Philosopher

Father of plant taxonomy

Classification of plants was based on:• Mode of generation• Locality• Size• Usefulness

Carl von LinnéCarolus Linnaeus

Swedish botanist, zoologist, and physician

First to illustrate the usefulness of binomial nomenclature

Developed the modern taxonomic hierarchy

Binomial NomenclatureModern Hierarchy (Biological Classification)

Domain – Eukarya Kingdom – Animalia Phylum – Cordata Class – Mammalia Order – Primates Family – Hominidae Genus – Homo Species – Homo sapiens

Specific epithets:Descriptives – Quercus macrocarpa

= Oak with big fruitHonorifics – Quercus buckleyi

= Oak named for Mr. BuckleyLocalities – Quercus virginiana

= Oak first described in Virginia

= a two-word name consisting of a generic name and a specific epithet

Current system recognizes 3 Domains:Eukarya:

Kingdom AnimaliaKingdom PlantaeKingdom Fungi

Archaea & Bacteria

The previously recognized Kingdoms ofProtista & Monera have been disolved

Phylogenetic Classification

= the evolutionary history of a species or group of species

Typically represented as a phylogenetic tree (cladogram) a branching diagram showing the

evolutionary relationships among various biological species or other

taxa that are believed to have a common ancestor

The Pylogenetic Tree

http://static.newworldencyclopedia.org/7/70/Phylogenetic_tree.svg

Time

Species 1 Species 2 Species 3

Plant Classification

Current classification systems follow the recognized taxonomic hierarchy, however, there is always some

disagreement as to the membership requirements of various taxa

Lumpers&

Splitters

The Core

Plant Classification

Non-vascular land plants• reduced plants that

lack vascular (circulatory) tissues

• they neither have flowers nor produce seeds

• reproductive unit is a spore

Ferns and fern allies• plants with vascular

(circulatory) tissues• they neither have

flowers nor produce seeds

• reproductive unit is a spore

Gymnosperms• plants with vascular

(circulatory) tissues• they lack flowers • reproductive unit is a

seed produced on scales in a cone-like structure

Angiosperms• plants with vascular

(circulatory) tissues• they produce flowers • reproductive unit is a

seed produced within an enclosed ovary

Identification

= the assigning of an existing name to an unknown organism

Methods

Expert assistance – local university, school, museum

Comparison method – guide books, internet

Dichotomous key – local manuals, floras

Dichotomous Key

Keys based on a sequence of pairs of contrasting statements

The user chooses the statement that better describes the plant in question

Each time a choice is made a number of plants are eliminated

Eventually the number of possible identifications is reduced to one

Dichotomous Key

1. Growth habit an herb1. Growth habit a vine, shrub or tree

. . . . . . . . . . . . 2 . . . . 4

4. Growth habit a vine4. Growth habit a shrub or tree

. . . . . . . . . . . . 5 . . . . . . . 7

7. Growth habit a shrub7. Growth habit a tree

. . . . . . . . . . . . 8. . . . . . . . . . . . 30

Dichotomous Key

30. Leaf arrangement opposite30. Leaf arrangement alternate

. . . . Fraxinus . . . . . . . .

31

31. Leaves simple31. Leaves compound

. . . . . . . . . . . . . . . 32 . . . . . . . . . . . . 44

32. Venation palmate32. Venation pinnate or reticulate

. . . . . . . Washingtonia. . . . . . 33

Dichotomous Key

33. Margin entire33. Margin toothed

. . . . . . . . . . . . . . . 34 . . . . . . . . . . . . . . 39

34. Lobes present34. Lobes absent

. . . . . . . . . . . . . . . 35 . . . . . . . . . . . . . . 37

35. Blades palmately lobed35. Blades pinnately lobed

. . . . . Platanus. . . . . . . . . 36

Dichotomous Key

36. Lobes rounded36. Lobes pointed

. . . Quercus macrocarpa . . . . . Quercus buckleyi

Thank You

It is both an honor and pleasure to speak before the Master Naturalist

I wish you all continued success