Weber State University          Department of Botany

                                                    Botany SI2104-Plant Form and Function
 

What is a plant?
Traditionally, two groups of organisms:  Plants and Animals

Sorting organisms into one of the two groups was fairly easy for large, multicellular organisms.  As microscopes were invented and improved, all kinds of smaller organisms, including lots of unicellular organisms, were discovered.  It became harder and harder to put them into one of the two existing groups.  Basically, if you weren’t obviously animal, you were a plant.

Traditional Classification of Organisms:  Two Kingdoms

In the 1860s, Hogg and Haeckel proposed a third Kingdom for all organisms that did not form complex tissues  ----> Protista (Protoctista)

J. Hogg and Ernst Haeckel.  1860s.  Three Kingdoms.

In 1938, Copeland proposed a fourth Kingdom for the prokaryotic protists.

Herbert  F. Copeland.  1938.  Four Kingdoms.

In 1969, Whittaker noted the varied nutritional status of the protists and proposed a Kingdom for the fungi.

R. H. Whittaker. 1969.   Five Kingdoms.

The five Kingdom classification provided three Kingdoms for complex (multicellular) eukaryotes based on their nutritional status and life cycle:
Plantae:  autotrophic; sporic life cycle
Animalia:  heterotrophic (ingestion); gametic life cycle
Fungi:  heterotrophic (absorptive); zygotic life cycle
There was a catch-all Kingdom for the remaining eukaryotes (Protista) and a single Kingdom for all prokaryotes (Monera).   Problem:  people were starting to find a distinctly different type of prokaryote.

Carl Woese.  1981.    Six Kingdoms. 

Today
Three Domains: Archaea, Eubacteria, Eukarya
 

What does a traditional Botany survey class cover?  The organisms in the traditional Plant Kingdom.  Most of this course will focus on the flowering plants with some mention of the conifers when we get to secondary growth.  Bacteria and fungi will be covered from the perspective of their interactions with plants with regard to mineral nutrition.

Classification

Levels of Classification

Plants --->  Vascular Plants --->  Seed Plants --->  Conifers (Coniferophyta) (one phylum of the gymnosperms)
Plants --->  Vascular Plants --->  Seed Plants --->  Flowering Plants (Anthophyta or Magnoliophyta)  (the angiosperms)
Two classes of Anthophyta:   Liliopsida (Monocotyledones => monocots), Magnoliopsida (Dicotyledones => dicots) 
    or Three classes of Anthophyta:   Monocotyledones => monocots, Eudicotyledones => eudicots, Magnoliids ==> a diverse group that includes the former dicots that are not eudicots

Species name = genus + specific epithet = binomial, a unique name in Latin
Why Latin?  dead language, universal
problems with common names:  many per plant, many languages, used for > 1 plant
The specific epithet is essentially an adjective that describes the genus.  A genus name must always accompany a specific epithet when referring to a species.  Check here for a list of species that have the same specific epithet.
Genus and species names are either written in italics or underlined.  The name of the authority who named the plant (L. = Linnaeus) is not italicized or underlined.

Suggested Online Reading

Classification (from Michael Knee at Ohio State University)

Systematics (from Steven Wolf at California State University Stanislaus) 
Systematics is a broad term that covers the scientific study of  the genetic and evolutionary relationships between organisms.  One aspect of systematics is classification. 

Naming and Classification of Fungi  (from George Wong at the University of Hawai`i at Manoa) 
This reading is not just about the fungi.  It covers general information about classification of organisms, including historical background.  Be sure to follow the "click to continue" link and read all three "pages" on the topic.

History and Development of Classification (from Jodie Ramsay at Northern State University)

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10 January 2007.  Links checked 13 August 2009.