Taxonomy is probably the oldest science and certainly almost from the beginning of human existence plants have been classified based on their edibility, and other uses to humans.

A. Note three cultures all based on different member of grass family: European - wheat, Oriental - rice, American - maize (corn).

B. The development of western plant taxonomy has at least five distinct periods:

• Preliterate
• Ancient literate
• Medieval or dark ages
• Renaissance
• Theory of Evolution

I. Preliterate - since this is pre written record, we have little direct knowledge of this period.

A. However, through the years, all cultures have learned which of the plants around them are useful, whether for medicines, food, clothing, shelter, weapons, etc.

B. We certainly have much archaeological evidence and even information from ancient paintings, drawings or utensils, and even common sense tells us that humans have always known something about the plants around them and their uses. Obviously they knew which were edible and which were poisonous.

C. Also virtually all civilizations have taken advantage of the medicinal properties of plants. In most cultures the medicinal aspects of plants were closely guarded secrets and probably passed on from medicine man to medicine man.

1. In almost all cultures, even today, medicinal information is concentrated in the hands of a few, whether it be witch doctors, medicine men, shamans or even doctors. As you will shortly see, its only in the past few hundred years that plant taxonomy has progressed past classification based on medicinal properties.

D. Even today we can learn a great deal about plants from so called "primitive" cultures that are occasionally discovered.

1. We often learn that they have many uses for plants that were previously unknown. In fact today there are government sponsored botanical expeditions to little known cultures, particularly in the tropics, to learn local uses of plants.

a. Many have already given us valuable products, e.g. just from Latin America: potato, sweet potato, tomato, cassava (manioc), rubber, cocoa and numerous medicinal plants such as quinine, cocaine and its derivatives or tobacco.

II. Ancient literate western civilization - the development of writing is certainly a major milestone in human history and it's therefore not surprising that what we know of western taxonomy starts in ancient Greece.

A. Theophrastos ca. 300 BC, Greek who studied under Plato and Aristotle and considered grandfather of botany.

1. He wrote more than 200 works only a few of which survived. The most important were: Enquiry Into Plants, and The Causes of Plants. Was a friend of Alexander the Great who had a botanical interest and who sent him plants from his travels.

2. Wrote about 500 species of plants and described cotton, pepper, cinnamon, bananas and named many modern genera including Asparagus and Narcissus. Among his most significant observations are:

• distinctions between external (organs) vs. internal (tissue) structures.
• distinction between different kinds of tissues.
• classification into trees, shrubs, subshrubs and herbs.
• distinction between flowering vs. non-flowering plants.
• recognition of different kinds of sexual & asexual reproduction.
• understood basic anatomy, e.g. sepals & petals modified leaves.
• true understanding of fruits.

B. Pliny the Elder Roman (ca. 50 AD) chief work was Natural History a multivolume work of which 37 volumes survive, in which he tried to record everything that was known about the world. About 1/4 was devoted to Biology. Most of the botany was devoted to medicine or agriculture. For more than 1,000 yrs. this work revered and it was one of the first to be printed by movable type.

C. Dioscorides - Greek contemporary of Pliny in 1st century AD. Wrote one of the oldest surviving and most influential natural history books ever written, Materia Medica. It was an account of plants of medicinal value.

1. Until the Renaissance (1500's) this was the reference work. During the Dark Ages it was copied and recopied and the figures redrawn so many times that they bore little resemblance to the original. However, since the masses couldn't read anyone who possessed a copy was guaranteed fortune and success, it allowed one to practice pharmacy and medicine. It recognized some natural families such as the mints and carrot as well as some modern genera such as Aloe.

III. Medieval or Dark Ages - The period from the fall of Rome to the Renaissance often called Dark Ages because very little original thought or work. What little scholarship there was consisted of copying the ancient works of the Greeks and Romans. Unfortunately this led to considerable loss of information or much misinformation.

A. Only one botanist of note: Albertus Magnus (St. Albert) ca. 1250. Employed classification which recognized mono vs. dicots as well as vascular vs. nonvascular.

IV. Renaissance - started ca. 14th century Italy and marked by period of original thought and flowering of the arts, literature and the beginnings of modern science.

A. Two major technological innovations contributed to Renaissance and especially to plant taxonomy:

1. printing press

2. science of navigation

The former made knowledge available to all and botanical-medical books called herbals became popular. Navigation started the age of exploration and almost immediately the number of known plants increased dramatically. New systems of classification were needed to handle this increase.

B. Basically four distinct periods to this era.

1. Herbalists - (1500's) motivated by practical considerations, i.e. medical and agricultural uses of plants.

a. No real systems of classification but marked period of original work rather than copying the ancients work. These books were based on first hand observations by the authors and provided detailed and accurate description of the plants of medicinal use.

b. Several prominent Germans: Brunfels, Bock, Fuchs (Fuchsia).

2. 17th century - Large numbers of new plants from voyages necessitated better systems of classification.

a. Caesalpino - (Italian) tried to base classification on logic rather than utilitarian concepts (such as medicinal uses). He realized that some features are more meaningful than others in classification, a priori reasoning (today emphasis on floral features).

b. During this period Aristotle's type concept came into vogue. Maintained that species non-varying and fixed entities and based on an ideal or fixed embodiment or type. Generally thought to be the ideal created by god. Not to be confused with nomenclatural type concept.

c. Bauhin (Swiss) Wrote Pinax which was a register of plants know to science at that time.

1. He also included other names for the plants, i.e. SYNONYMY. Also generally credited with modern concept of genera and species.

2. He also experimented with BINOMIAL system of naming plants.

3. Linnaean period - 18th century. By end of 17th century there were too many new plants to deal with and plants were referred to by descriptive Latin phrases.

a. Linnaeus, a Swedish physician, is considered the father of plant taxonomy and one of his works, Species Plantarum (1753) is the starting point for modern taxonomy.

b. He realized that some characters were more useful than others and he developed a Sexual System of classification which was based on the numbers of reproductive parts. Purely artificial but allowed one to easily identify an unknown plant by keying it out much as we do today.

c. He described 100's of species, all binomials that have a L. after them. His most significant contribution was the consistent use of the binomial system in which each species was referred to by only two names, the genus and specific epithet.

d. Species Plantarum (May 1, 1753) is the nomenclatural starting point for virtually all plant names.

4. Natural systems - by late 1700's botanist began to ponder the purposes of taxonomy and to try to provide more information content in their classifications, i.e. they wanted to reflect "natural relationships". Although Linnaeus had provided a convenient method for identifying plants, it was clearly artificial, e.g. Cacti and pines were classified together because they had numerous male parts.

a. Adanson - rejected a priori choice of characters and felt that using as many characters as possible would give the most natural or useful classification.

• This is the precursor of Phenetic or modern computer aided Numerical Taxonomy which is often called Adansonian Taxonomy.

b. de Jussieu's a French family (mid 1700 to 1800's) included 4 botanists, father and sons. First to arrange plants into a natural system, i.e. plants which looked alike were grouped together.

• Arranged the plants in the Paris botanical garden in such a fashion.

c. Bentham & Hooker Englishmen of late 1800's worked out of Kew Gardens in London and largely responsible for establishing it as foremost systematic institution in the world. Much of the material from early explorations was deposited here.

• Wrote Genera Plantarum over 20 years, was a compendium of generic descriptions arranged in a natural system. Their descriptions were taken from original material and are noted for their completeness and detail and are still widely consulted today.

V. Theory of Evolution - Darwin published his On the Origin of Species in 1859. Almost immediately accepted by scientists and rapidly became one of the unifying concepts of biology.

A. Two major concepts impacted on classification:

1. species have evolved from one another over time, i.e. species have evolutionary histories - Phylogenies.

2. species are not represented by ideal types as Aristotle thought, but by variable populations.

B. Since Darwin's time most systems of classification have tried to reflect evolutionary relationships.

1. The first to do so were the Germans, particularly Engler and Prantl who wrote multivolume Die Naturlichen Pflanzenfamilien from 1887-1915. They arranged the plants in an evolutionary sequence starting with the presumed primitive ones and ending with the most advanced.

• One major flaw was their assumption that simple equals primitive. Now known that many seemingly simple structures evolved from more complex structures via reductions. E.g. some plants don't have both sepals and petals, these might be considered as primitive and plants that have both might be considered advanced. However information from the study of fossils as well as anatomy indicate that some primitive flowers had both sepals and petals and the ones that evolved from them lost one or both.
• Until about 1980 it was the world standard and all herbaria and floras were arranged according to it. Now replaced by Cronquist system which we'll use.

2. Bessey - from U. Nebraska early 20th century devised a set of dicta as to what features were primitive versus what were advanced.

• Primitive refers to those found in the most ancient plants, advanced are found in the most recently evolved plants. Bessey developed a system of classification based on these dicta and it resembled a cactus.

3. Cronquist (Cronquist system) from NY Botanical Garden and Takhtajan from Botanical Institute in St. Petersburg (Leningrad).

• Working independently they both came up with strikingly similar classifications around 1968. Both represent syntheses of data from virtually all areas of botanical science, e.g. anatomy, genetics, physiology, paleobotany, chemistry, etc.
• Cronquist's seems to have gained much wider reception and is now most popular, probably in large part to being in English.

Other work which has influenced modern taxonomy

I. By the beginning of the 20th century most botanists realized there were some problems with species concepts but most agreed that species were morphologically distinct entities. Also by beginning of this century the floras of Europe and Northern America were largely past the pioneer and consolidation phases and sufficiently well known that many scientists began experimental or biosystematic investigations of plants. Although not necessarily taxonomists and some not even botanists, their work has had profound influences on plant systematics.

A. O. Winge (1917) Denmark demonstrated the utility of using characters of chromosomes and noted different chromosome numbers in plants. Cytology, cytotaxonomy.

B. Turesson (1920's -30's) a Swede began experimental studies to document variation within species, genecology. Populations of species were adapted to different environments, ecotypes.

C. Camp and Gilly 1930-40's wrote on the species concept in plants. Plants much more complex than animals and no satisfactory single species definition. They recognized a dozen different types of species.

4. Clausen, Keck & Heisey 1940's began series of elaborate transplant experiments in different environments in California. Contributed significantly to ecotype concept. Important in speciation.

5. Huxley 1940 edited New Systematics argued that old taxonomy was dead and new approaches were needed.

6. Alston & Turner 1959 Biochemical Systematics recognized the importance of chemistry in taxonomy

7. Hennig - 1966 a German zoologist published work on phylogenetic analysis called cladistics. Once this work was translated, it had a major influence on plant classification. It set out some rules and procedures for phylogenetic analysis and has had a major influence on modern plant taxonomy. We'll cover some aspects of cladistic analysis.

8. Palmer early 1980's - field of molecular systematics, began using DNA analyses.

Current taxonomic activities are largely concentrated in three major areas:

1. Monographs - detailed investigations of a particular taxon, i.e. a genus, subgenus, section, species etc. Includes complete descriptions, distributions, keys to the taxa and other information such as chromosome numbers, historical or ecological data.

2. Floristics - inventories and manuals of plants for particular regions. Still much to be done. Great Plains Flora, Jepson Manual for California, Flora of North America. Major emphasis in tropical areas.

3. Biosystematic or evolutionary - modern methods to investigate phylogenetic relationships. Often part of monographic works.

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