When you have a lot of things to keep track of, it is helpful to have an organizing scheme.
Where do you look for cookies at the grocery store?
How do you tell your friend where you live?
How do you find your favorite CD at the music store?
With as many living things as there are in the world, we need a good way to keep track.
History of Plant Classification
The development of western plant taxonomy has at least five distinct periods:
People have been using plants and naming and classifying them forever, even if not written.
Sometimes called folk taxonomy
poisons (on arrows for fishing or hunting)
narcotic, hallucinatory (spiritual practices)
Others returned later to functional classification schemes
First written classification scheme from ancient Greeks
Theophrastos ca. 300 BC, studied under Plato and Aristotle, considered father of botany.
Described 500 plant species, including cotton, pepper, cinnamon, bananas and named many modern genera including Asparagus and Narcissus.
Classified all plants as trees, shrubs, subshrubs, herbs (different forms)
Pliny the Elder 23-79 AD
wrote 37 volume Natural History encyclopedia
9 volumes on medicinal plants
Dioscorides (first century AD)
Roman military surgeon
Wrote Materia medica
Described 600 medicinal plants
preserved botanical works when
began again in
Printing press invented in 1440 AD
Herbals books of flora (description of plants in a given area), focus on medicinal use (functional)
Time of wide exploration
Now instead of hundreds of plant species, 15,000 species to be classified
In need of a new system to keep track
Carl Linnaeus (1707-1778)
Attempted an artificial classification scheme
A sexual system based on number & arrangement of stamens
Grouped unlike plants together (grouped cacti and cherries together)
Linnaeus was much more successful in proposing a new system for naming plant species Binomial nomenclature
Natural or Phentic Systems
Looks for natural affinities among species
No explicit methodology; largely intuitive
de Jussieu and de Candolle important early works (1700s, early 1800s)
Bentham and Hooker (mid-1800s)
Accepted Darwins theory of evolutionary change (1859)
But grouped plants just by similar features, not recognizing potential for change
Group plants by evolutionary relationships
Compiled a very detailed flora of all known vascular plants, with extensive illustrations and keys, arranging plant families according to contemporary theory of phylogeny
We currently recognize a different sequence of phylogeny, but Englers work remains valid in its exhaustive detail.
Current classification schemes remain based on our understanding of phylogenetic relationships among plants.
Important 20thC botanists in this effort include:
Each has built upon the works of earlier botanists.
Classification is still a work in progress.
The Taxonomic Hierarchy
Each category is called a taxon (plural = taxa)
Higher taxa are more inclusive
Names of most taxa (except Kingdom and above genus) are of a genus name with a suffix indicating taxonomic level
phylum (or division) -ophyta
Taxa may be formed in between these groups (subclass, tribe, etc.) but we wont use them.
Linnaeus was much more successful in proposing a new system for naming plants
Old system used Latin phrase names
For example, spearmint was known as:
Mentha floribus spicatis, foliis oblingis serratis
(Means mint, flowers in spike, leaves oblong and serrate)
Linnaeus proposed a binomial nomenclature
Spearmint becomes Mentha spicata
Proposed naming system called
All species names have two basic words: genus plus specific epithet. Genus is a noun, specific epithet is an adjective (or possessive noun) that modifies it.
Linnaea borealis L.
a. genus name
b. specific epithet
c. authority may be added
= who described (named) the plant
often abbreviated, e.g. Linnaeus = L. or Linn.
Linnaea borealis L.
First usage in a scientific publication
On formal herbarium labels
In Taxonomic literature
Rules for scientific names
Underlined or italicized
Use Latin words or words that have been Latinized
First letter of genus name is always capitalized. Rest of letters all lowercase.
1. Every vowel (or pair of vowels) pronounced Tolmiea
2. No silent letters at end Cardamine
3. First letter silent when: pt, mn, cn, gn Pteridium
4. ll is l not y Potentilla
Why use scientific and not common names?
Some species have more than one common name:
Oregon myrtle in OR
California bay in CA
Plantago major has over 100 common names in several languages
Some common names are used for more than one species
Cedar is used for species in at least 4 different general and two families
Cedrus, Thuja, Chamaecyparis, Juniperus