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
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