"There are two sorts of curiosity -- the momentary and the permanent. The momentary is concerned with the odd appearance on the surface of things. The permanent is attracted by the amazing and consecutive life that flows on beneath the surface of things."

-Robert Lynd, Solomon in All His Glory

Introduction

Where do plants fit in the scheme of things? In the earliest schemes, everything was either a plant or an animal (two "kingdoms"); As new and smaller organisms were discovered, they were originally classified as either plants or animals. So protozoa were grouped with animals, while fungi and bacteria were grouped with plants. Of course this system became outmoded (stretched) as time went on and more organisms were discovered (Chlamydomonas, a motile autotroph). About 1930, a third kingdom was added: Protista, although agreement was not complete. In about 1985, a robust 5-kingdom system was proposed, and in Principles of Biology in the last couple of years, students were taught about six kingdoms.

What is relationship between kingdoms? (drawing)

Protists

|-------------------Fungi

Eubacteria |-------------------Plants

| |-------------------Animals

Archaebacteria |---------------------/

|----------------------/

earliest life-------/

In this course, the rest of the lectures will take us on a "grand tour" of the non-animal groups above: bacteria, protists, fungi, and plants.

What is a plant? Your present concept of plants is probably quite accurate a far as it goes: most plants have green leaves, stems, roots, flowers, and seeds. Can you think of exceptions? (anyone who has just taken Principles of Biology II should be able to cite some examples). Conifers lack - what? Right, flowers. Cacti seem to lack leaves. Lower plants may lack stems (liverworts) and have rather undifferentiated bodies (thalli). Some botanists have included green algae with plants, but now they are classified with protists. The point is that plants as we see them today represent a large evolutionary continuum, with some groups having moved far from the ancestral state, and others having moved less. I will return to this theme:

In the plant kingdom, we currently recognize 12 divisions or phyla: bryophytes with 3, including liverworts (Hepatophyta, 17268), hornworts(Anthocerophyta), and true mosses(Bryophyta, 17465), seedless plants with 4, including whisk ferns(Psilotophyta), club mosses (Lycophyta, 18742), horsetails (Sphenophyta, 17762), and ferns (Pterophyta, 17307), and seed plants with 5 (Cycadophyta (17436), Gingkophyta (17224), Coniferophyta(17904), Gnetophyta, and Anthophyta). In this course, we will focus on Anthophyta (flowering plants), both in the lecture and in the collection.

Division Anthophyta

The angiosperms (Division Anthophyta) are by far the most common and familiar plants: most trees, shrubs, grasses, wildflowers, edible fruits, berries, nuts, grains, and vegetables are flowering plants. The division included about 235,000 species, and in general is almost stupefyingly diverse.

The two major classes of angiosperms are the dicots (Dicotyledonae or Magnoliopsida) and monocots (Monocotyledonae or Liliopsida). Dicots are believed to be older; monocots evolved from dicots, possibly from an aquatic dicot. Here is a list of the major differences between dicots and monocots. (Review this table (20844)).

The class Liliopsida (monocots) is generally recognized to have five subclasses: Alismatidae, Arecidae, Commelinidae, Zingiberidae, and Liliiadae.

The class Magnoliopsida (dicots) is generally recognized to have six subclasses: Magnoliidae, Hamamelidae, Caryophyllidae, Dilleniidae, Rosidae, and Asteridae.

Why did I say "generally recognized"? As a means of acknowledging the wide variation in classification systems for plants above the family level. There are several different classification systems developed by several authors. In my field botany class, I teach the one published by Arthur Cronquist in 1988. Using his system, he has inferred certain evolutionary relationships. As a beginning botany student, I suggest that you stick with Cronquist, as the best documented modern treatment, and let the taxonomists fight it out over the others.

What evidence do we have about these relationships? Botanists for hundreds of years have identified certain morphological characters of plants, especially of the flower and fruiting structures which vary in certain uniform or predictable ways. They have identified patterns in variation which they have used to infer these relationships.

Simply put, these characters can be thought of as either primitive or derived. Most plants show some combination of primitive and derived characters. In studying this list, it may help to think of Magnolia or Liriodendron as primitive and an orchid as derived.

*Primary wind pollination occurs in taxa so primitive that they never developed showy flowers for insect pollination (e.g. many Hamamelidae). Secondary wind pollination occurs in taxa so derived that they have lost their showy flowers (e.g. grasses).

Taxonomy and Nomenclature

Our current system of nomenclature is based on the Linnaeun system tracing back to the publication of "Species Plantarum" (1753). It is a system of binomial nomenclature in which each species has a two word latin name consisting of its genus and species names. These words are always underlined or italicized when written.

It is a hierarchical system, meaning that groups are nested inside larger groups.

For example:

Kingdom Plantae

Division Coniferophyta

Class Coniferopsida

Order Coniferales

Family Pinaceae

Genus Pinus

Species Pinus taeda

Classification is the sorting of things into groups and the assigning of names to those groups. Artificial classification is one with no regard for evolutionary relationships (e.g., any classification of things other than living things). Linnaeus called his system the "Sexual System", because he used the presence or absence and number of sexual parts as the basis for classification.

Natural classification - reflecting evolutionary relationships. Darwin was the first to suggest that any classification of life should be "genealogical" and would naturally be hierarchical. Much of the Linnaean system is still intact, because the characters he

used are good indicators of evolutionary relationships. Phylogenetic classification - Today we specify that the system must reflect phylogeny, because for many years people have called systems "Natural" which do not include monophyletic groups.

What does this mean - phylogenetic? monophyletic?

Phylogeny - the pattern of relationships of living things. It consists of many

monophyletic groups arranged in a nested branching hierarchy and often

is depicted as a tree.

Monophyletic group - a group of species that are all derived from the same common

ancestor and which includes all descendants of that ancestor. Think of a tree with

species as leaves at the tips of all the branches. If you cut off a branch at any one

point, the portion that is cut off is a monophyletic group.

In a phylogenetic classification, all groups that are recognized with a name will be monophyletic.

Nomenclature

INTERNATIONAL CODE OF BOTANICAL NOMENCLATURE (ICBN) governs the naming of plants. Six principles form the basis of the code:

1. Botanical nomenclature is independent of zoological nomenclature.

2. The application of names of taxonomic groups is determined by the means of nomenclatural types, a specimen.

3. Nomenclature of taxonomic groups is based on priority of publication.

4. Each taxonomic group can have only one correct name, the earliest that is in accordance with the rules (some exceptions).

5. Scientific names are latinized.

6. The rules are retroactive (some exceptions).

TWO PURPOSES OF THE ICBN:

I. DENOTE RANKS OF TAXONOMIC GROUPS, i.e. the hierarchy.

Kingdom Division - phyta Class - opsida, Subclass - idae Order - ales Family - aceae - (except 8 conserved names) Genus Species

II. LAY DOWN RULES FOR THE NAMING OF PLANTS WITHIN THESE GROUPS.

One of the primary activities of taxonomy is the naming of new taxa as well as the remodeling of old taxa. Frequently upon further study it is determined that some taxa must be remodeled, i.e. divided, united, transferred, or changed in rank.

1. Divided - make two taxa out of one.

2. United - combine two or more taxa into one.

3. Transferred - decide that one taxon belongs in another, e.g. a species belongs in another genus.

4. Changed in rank - e.g. make a subspecies a species or vice versa.

CORRECT NAME:

Each taxon can have only one correct name. A correct name must be legitimate and validly published:

I. LEGITIMATE NAME - is one in accordance with the rules.

II. VALIDLY PUBLISHED NAME MUST BE:

1. Effectively published, i.e. published in printed matter generally available to botanists.

2. In the proper form for that taxon, e.g. family ending in -aceae, or masculine or feminine ending of epithets.

3. Accompanied by a description or reference to a previously published taxon.

4. Accompanied by a Latin description or reference to a previously published taxon.

5. Nomenclatural type must be designated.

TYPE SPECIMENS:

Nomenclatural Type - specimen of specific rank to which the name of the taxon is permanently attached.

Some exceptions:

1. Valid publication of vascular plants starts on May 1, 1753, with a few exceptions.

2. Principle of priority not binding above family rank.

3. Rules retroactive except Latin description required after Jan. 1, 1935.

TYPES OF TYPES:

1. Holotype - the one specimen used or designated by the author as the nomenclatural type. As long as it is extant it automatically fixes the application of the name.

2. Isotype - a duplicate (part of a single gathering made by a collector at one time) of the holotype.

3. Lectotype - a specimen selected from the original material to serve as the type when no holotype was designated or if it becomes missing.

4. Syntype - any one of two or more specimens cited by the original author when no holotype was designated or any one of two or more specimens simultaneously designated as types.

5. Neotype - a specimen selected to serve as the type as long as all of the material on which the name of the taxon was based is missing.

PRIORITY FOR SELECTING NOMENCLATURAL TYPE:

Sometimes no holotype was designated or it is lost. In such a case a new type must be selected. Listed below, in order of preference, are the sources which should be considered.

A. Lectotype

1. Isotype

2. Syntype

B. Neotype - only last resort if none of original material is extant.

Now, all this nomenclatural stuff is admittedly arcane and difficult. Why should you care? You really do not have to worry about it most of the time, except when publishing scientific research. It can be a pain in the neck to keep track of changing botanical names, but it is certainly something you want to keep in the back of your mind. Sometimes you can gloss over the issue by simply citing the flora you use as the authority. Certainly, if you do things like wetlands determinations or delineations, you will want to pay attention to nomenclatural changes. Best done by consulting an expert.