Plant nomenclature & taxonomy Dr. Mbinji Omale Introduction • Arrangements of plants into groups and subgroups are commonly rereferred to as classification. • Various systems of classifying plants have gradually developed during past few centuries which have emerged as a discipline of botanical science known as Taxonomy or Systematic botany. • The Taxonomy word is derived from two Greek words ‘Taxis’ meaning an arrangement ‘nomos’ meaning laws. • Therefore, the systemization of our knowledge about plants in an orderly manner becomes subject matter of systematic botany History Many attempts were made in the earlier days to name and distinguish the plants as well as animals. • Earliest mentions of classifications are credited to the Greek scientist Aristotle (384–322 B.C.) who is also called as the father of natural history. • Aristotle attempted a simple artificial system for classifying number of plants and animals on the basis of their morphological and anatomical resemblances. It worked with great success for more than two thousand years. Theophrastus (370–285 B.C.), the first taxonomist who wrote a systematic classification in a logical form was a student of Aristotle. • He attempted to extend the botanical knowledge beyond the scope of medicinal plants and classified the plants in about 480 taxa, using primarily the most obvious morphological characteristics, i.e. trees, shrubs, under-shrubs, herbs, annuals, biennials and perennials. Cont. A. P. de Tournfort (1658–1708) carried further the promotional work on genus. • He had a clear idea of genera and many of the names used by him in his Institutions Rei Herbariae (1700) were adopted by Linnaeus. • Tournfort’s system classified about 9000 species into 698 genera and 22 classes. • This system although artificial in nature was extremely practical in its approach. • John Ray (1682), an English Botanist used a natural system based on the embryo characteristics. • Most important of his works were Methodus Plantarum Nova (1682), Historia Plantarum (1686) and Synopsis Methodica Stirpium Britanicarum (1698). • He classified the plants into two main groups: Herbae, with herbaceous stem and Arborae, with woody stem. Cont. Carrolus Linnaeus (1707–1778), a Swedish botanist, introduced the system of binomial nomenclature. • His artificial system was based oh particular names of a substantive and adjective, nature. • It is best known as binomial system of nomenclature in which the first general name indicates the genus and the second specific name denotes the species. • Linnaeus characterized and listed about 4378 different species of plants and animals in his works Species Plantarum and Genera Plantarum (1753). • He classified plants on the basis of reproductive organs, i.e. stamens and carpels—and hence this system is also known as the sexual system of classification. Why classify? • Plant taxonomy is the system of classification used by botanists and horticulturists to organize plants and identify them clearly. This is an improvement on the models developed by Linnaeus who simplified the naming procedure through the "binomial" system. Evolutionary classification Living species are related to one another by descent from common ancestors Shared character states are clues to relatedness Aim of classification 1. Simplify 2. Communicate 3. Predict with accuracy Plant nomenclature in practice Kingdom- Viridiplantae (green plants) Phylum/Division- Embryophyta (land plants) Subphylum- Tracheophytina (vascular plants) Class- Angiospermopsida (angiosperms) Subclass- Caryophyllidae Order- Caryophyllales Family- Portulacaceae (Purslane family) Genus- Lewisia Species- Lewisia rediviva Higher ranks • - Each rank has a characteristic ending (ex. -idae for subclasses, -ales for orders) • - Ideally, all taxa are monophyletic, but ranks are arbitrary • - we’ll focus on lower taxonomic levels --> subclass (ex. Rosidae vs. Asteridae) --> family (ex. Salicaceae vs. Betulaceae) --> genus (ex. Solanum) --> species (ex. Solanum nigrum L.) Cont. ICBN (International Code of Botanical Nomenclature) Goal: Standardization of scientific names for plants - First adopted in 1903; includes fungi, lichens and algae Basic rules - Every taxon must have a type specimen - Names of higher ranks must be based on names of lower ones - Priority of publication determines “correct” name - Only 1 name is allowed per taxon, 1 taxon per name Cont. • Families - All end in -aceae (easiest to pronounce a-cee-ee) - Older alternate names also allowed for 8 families examples: Crucifereae = Brassicaceae (mustard family) Umbellifereae = Apiaceae (carrot family) Compositae = Asteraceae (sunflower family) Labiatae = Lamiaceae (mint family) Leguminosae = Fabaceae (bean family) Always capitalize family names • Linnaeus' binomial system uses one Latin name to indicate the genus, and another to indicate the specific epithet. • Together, the genus and epithet comprise the "species." By definition, "binomial" means "characterized by having two names," from the prefix "bi-" (indicating "two") and the Latin word for "name," nomen. • By using the binomial system of nomenclature, plant names are the same in all languages! • Every plant has a “first and last name” where the last name is written first. • Genus (plural genera) Cont. • All specific names may be written with small initial letters although formerly capitals were used where species were named after persons. • Thus the species of Cinchona named after Charles Ledger, who brought its seeds from Brazil in 1865, is now written Cinchona ledgeriana rather than Cinchona Ledgeriana. • The specific name is usually chosen to indicate some striking characteristic of the plant. • for example, the hemlock with the spotted stem is named Conium maculatum (maculatus, -a, -um, spotted). • Sometimes the reason for the name is not as obvious as in the example just mentioned, but once it is discovered it will serve as a reminder of a characteristic of the plant • for example, Strychnos potatorum (potator, -oris, a drinker) bears a name which is only intelligible when it is known that the seeds of this species are used in India for clearing water. • A particular species can also exhibit a number of varieties; these are especially evident with cultivated plants but are also found in the wild. Cont. • Unlike the names of chemical substances, which are subject to changes which conform to evolving systems of nomenclature, systematic plant names are strictly controlled by rules which give precedence to that name used by the botanist who first described the species. • Nevertheless, this seemingly straightforward approach can give rise to various quirks in spelling 1. Rauvolfia vis à vis Rauwolfia-the former name was given to this Apocynaceous genus by Plumier in 1703, honouring the botanist Leonard Rauwolf. 2. Datura innoxia or Datura inoxia. 3. Erythroxylum or erythroxylon. Find out? Genus name (PL. genera) • It is a Latin name, always capitalized and underlined or written in italics. • Genus name usually describes the following: A plants appearance- Hemerocallis (day and beauty) Supposed medicinal qualities- Pulmonaria (lungwort) Resemblance to body parts- Hepatica (liver) Honors a person by using their name – Kalmia (Peter Kalm) Specific epithet • This is the second word in a scientific plant name, not capitalized and written in italics or underlined. It is usually an adjective used to describe size, color, leaf shape, growth habit, origin of the plant or to commemorate a person. The epithet can be both singular and plural. Cotoneaster horizontalis Coreopsis gigantea Cistus x purpureus Chionanthus virginicus Turrea kokwaroana Kigelia africana Piper nigrum Citation authority • Sometimes yet another word is added after the genus name and epithet, which is neither italicized nor set off by quotation marks -- the name of the person who first described the plant. These names are sometimes abbreviated. When the name is abbreviated as "L," it stands for "Linnaeus." Primula vulgaris Huds (Hudson) Geum rivale Linn (Linnaeus) Ocimum kilimandscharicum Guerke • Zingiber officinale Roscoe Writing plant names by the rules • Scientific names should always be underlined or in italics • The genus is capitalized, the specific epithet is not • The name is only complete if it is followed by the name of the person who first described or named it. Red Oak: Quercus rubra Linnaeus Or Quercus rubra L. Plant species can be divided more into; 1. 2. 3. Cultivar Variety Hybrid cultivar Have distinguishing characteristics form the other plants in the species, but cultivars do not transfer those characteristics to offspring through sexual reproduction Names written with a single quote A cultivar of red maple is written as: Acer rubrum, ‘October Glory’ Acer rubrum cv. October Glory • The cultivar name is written after cv. or within single quotes with the first letter capitalized. • Unlike variety names, cultivar names are not underlined or italicized. • The full name of a cultivar is the accepted botanical name in Latin form, followed by the cultivar name. • Each word of a cultivar epithet must start with an initial capital letter unless it is a word after a hyphen or a conjunction or preposition which is not the first word of the epithet. Variety • A subdivision of a species that has a difference and breeds true to that difference. • Written in lower case and italicized or underlined ex. Pinus contorta var. latifolia Lodgepole Pine. -McIntosh -Cortland -Red Delicious -Jonathon Liberty Written in lower case and italicized or underlined ex. Pinus contorta var. latifolia Lodgepole Pine Hybrid • Two closely related but distinct species will be interbreed to form a hybrid • Are often sterile and produce no seed or fruit • Ex. seedless watermelon. • Written in lowercase and italicized or underlined an “x” is placed between the genus and hybrid epithet : Plantanus x acerifolia • Cross between Platanus occidentalis and Plantanus orientalis Integrated approach to plant identification ― Visual inspection of plant characteristics ― Photographic references ― Plant Classification keys ― Expert Advice • International Code of Botanical Nomenclature- is an international body that sets the rules for naming plants- provides guidelines for standardizing the naming of plants. The rules are revised as new scientific evidence becomes available. Basic Latin definitions ― Acorus= herbaceous marsh plant ― Alata= winged ― Altus= tall ― Amarum=bitter ― Bicolor= two colours ― Bifida= twice cut or cleft ― Biflora= double flowered ― Biloba= double lobed ― Brachyloba= short lobed ― Breviflora= short flowered ― Brevicapus= short stemmed ― reptans = a creeper Assignment Look for the meaning of the specific epithet and give ONE use of the plant. • Lippia ukambensis, • Rumex abbysinica, • Ipomoea grantii, • Caenorhabditis elegans, • piper album, • Gossypium hirsutum Thank you
