- - AGRICULTURE CORE CURRICULUM - - (CLF6000) Advanced Core Cluster: ORNAMENTAL HORTICULTURE (CLF6100) Unit Title: BOTANICAL CLASSIFICATION ____________________________________________________________________________ (CLF6102) Topic: PRACTICAL TAXONOMY Time Year(s) 1 hour 3 / 4 ____________________________________________________________________________ Topic Objectives: Upon completion of this lesson, the student will be able to: Learning Outcome #: (A-3) - Discuss three reasons for the current use of the modern system of plant classification (e.g., language barriers, universal names, and standardization of evolutionary similarities). Special Materials and Equipment: References: Cooper, Elmer L. (1990). AGRISCIENCE: FUNDAMENTALS AND APPLICATIONS. Albany, NY: Delmar Publishers. Bailey, L. H. (1976). HORTUS THIRD. New York: Macmillan. Harrington, H. D., & Durrell, L. W. (1957). HOW TO IDENTIFY PLANTS. Athens, OH: Ohio University Press. Hartmann, H. T., Flocker, W. J., & Kofranek, A. M. (1981). PLANT SCIENCE: GROWTH, DEVELOPMENT, AND UTILIZATION OF CULTIVATED PLANTS. Englewood Cliffs, NJ: Prentice-Hall. Evaluation: Unit Exam ===================================================================== *** INSTRUCTORS PLEASE NOTE *** The detail of this topic presentation goes beyond the scope necessary to meet the requirements of the Core Cluster in this area. It will take longer to teach than indicated above if covered entirely. It is included for local enrichment as appropriate to the class. ===================================================================== TOPIC PRESENTATION: PRACTICAL TAXONOMY REVIEW: The largest plant grouping horticulturists use on a routine basis is the family: --Hundreds exist --Suffix "-ACEAE" indicates family --Written in all capitals (i.e., MALVACEAE, ROSACEAE) The minor taxa, below the level of plant families, are even more frequently used. A. Minor Taxa 1. Genus--(plural "genera") This is the first of the two-part "binomial" name given each plant. Genus names often derive from persons, either real or those of mythical or literary note (i.e., Heuchera spp. after the German botanist Heucher), classical plant names, or descriptive information (i.e., Pyracantha spp.: 'pyr'-fire; 'acantha'-thorn for the burning thorns which arm these plants). Some rules governing the genus: a. Always capitalize the first letter only. b. Underline or italicize the whole word. c. It may be abbreviated, in a list, with its first letter, i.e., Quercus alba Q. lobata Q. rubra 2. Species--(plural "species") This is the second part of the binomial plant name. Species are groups of plants which are closely enough related that they may interbreed freely and have many characteristics in common. Their names derive from people (i.e., Rosa woodsii, after Joseph Wood), places (i.e., Ligustrum japonica after its native Japan), genus names and characteristics (i.e., Eucalyptus ficifolia, having leaves like a Ficus plant), or descriptive information (i.e., Hydrangea Macrophylla: 'macro'-big; 'phylla'-leaf. Some rules surrounding species names: a. Use all lower case letters. b. Underline or italicize the word, just like the genus. c. Use the abbreviation "sp." when there is uncertainty about which species a single plant belongs to. Use "spp." to indicate a group of several individual species within a genus, i.e., Quercus spp. to indicate the oak trees as a group. These abbreviations are not italicized or underlined. d. To be technically complete, the binomial name must end with an "authoritative epithet." This is a name or abbreviation after the species name which indicates who the person was who named the plant, i.e., Camellia japonica L. after Carolus Linnaeus, the famous botanist who first named the Camellia. Outside the academic environment, authoritative epithets are not a concern. 3. Sub-Specific Classification: Sometimes it is necessary to identify plants within a species that have special characteristics unlike the others. A useful comparison is to point out that all human beings are of the same species, Homo sapiens, but our different races and regional variations differentiate us within the realm of humanity. Likewise, many plants are noted for special characteristics within their species. Botanical specimens (those occurring in nature) are handled differently than horticultural specimens (those propagated and maintained through the influence of man). a. Botanical specimens are named according to the International Code of Botanic Nomenclature. Categories include: 1) Subspecies--principal sub-category used by botanists 2) Variety--the most commonly used sub-specific category. "var." is used as an abbreviation i.e., Buxux microphylla var. Koreana. The variety name is underlined or italicized along with the genus and species, but is not capitalized. 3) Form--used for very minor variants b. Horticultural specimens are named according to the International Code of Nomenclature of Cultivated Plants. 1) Group--below the species, but containing more than one cultivar of plants. 2) Cultivar is a term applied to many horticulturally sustained plants (i.e., Pyracantha coccinea 'Lowboy' or Ceanothus thyrsiflorus cv. Skylark). Some rules: a) Capitalize the cultivar name. b) Do not underline or italicize. c) Use the abbreviation "cv." or single quotes, but not both. d) Plural for cultivars is abbreviated "cvs.", when, for instance, discussing a number of named rose cultivars c. Hybrids are the special product of a cross between two diffent species of plants, usually within the same genus, but on rare occasions from different genera. The resulting offspring are unique plants different from either parent. There are two types: 1) Interspecific hybrids, indicated with a multiplication sign or an "X" between the genus and species name. For example, the hybrid species: a) Abelia X grandiflora--natural variation in population b) Platanus X acerifolia--intentional horticultural cross 2) Intergeneric hybrids are indicated by an "X" before the generic title, i.e., X Cupressocyparis leylandii. d. Graft chimeras are rare and are indicated by a "+" (i.e., + Laburnocytisus adamii). B. Common and Scientific Names: There is a need for both common and scientific or botanical names of plants, especially for those involved in horticulture. Following are some reasons we use both, and some of the associated problems: 1. Common Names of Plants a. Advantages: 1) Common names of plants are widely known and used. 2) Common names are usually simple and easy to remember. 3) Common names are often descriptive, i.e., "bluebell" instead of "Endymion." b. Problems: 1) There can be many names for one plant. For example, Umbellularia californica is commonly known as Oregon myrtle, California bay, bay laurel, pepperwood, and ironwood--five names (at least!) for the same plant. 2) Different plants may be called by one name, for example, sweet bay for both Laurus nobilis and Magnolia virginiana. 3) Common names are useful only in one language. 1. Scientific Names of Plants a. Advantages: 1) Botanical names have international value, and are understood by botanists the world over. 2) One name is given for one species of plant. This allows much less room for confusion. 3) Scientific names can often be descriptive, too. Some specialized knowlege of the meaning of Latin root words is helpful in understanding what the names mean (for example, Magnolia grandiflora indicating a kind of magnolia with large flowers). b. Problems: 1) Scientific names may change more often than common names. As more is found out about plants, and especially who might have been the first to name them, scientific names of plants can change. (For example, the Madagascar periwinkle changed from Vinca rosea to Catharanthus roseus. Many people still call it, incorrectly, "vinca." 2) The scientific names can occasionally be misleading. For example, Pittosporum undulatum suggests a very undulated leaf margin, when in actuality, P. tenuifolium is much more obviously undulated. 3) Scientific names can be obfuscatory or can be interpreted as an ostentatious display of knowledge. Sometimes common names are the best choice to effectively communicate what is meant. 1/6/91 MH/clh #%&C