Plant Names, Genera, species and Use of Botanical Latin

                                       Jesse L. Saylor, rev. August 26, 2009

             Plant names have been in use since man existed. In the Bible Adam named everything.

             Botanical Latin is used to communicate about plants around the world.

Latin was used in Roman and medieval times, and was the language of learning in Europe.

Latin names are printed like you see them here, even if the surrounding text is in Japanese, Russian, etc.

             John Ray (1627-1705), an English naturalist and botanist, emphasized the taxonomic

importance of the distinction between monocotyledons (plants whose seeds germinate with

one leaf) and dicotyledons (plants whose seeds germinate with two leaves).

For comparison, gymnosperms or conifers are multicotyledons with numerous seed leaves.

             Instead of a single feature, Ray attempted to base his systems of classification on all the

structural or morphological characteristics, including internal anatomy. Ray's enduring legacy to

botany was the establishment of species as the ultimate unit of taxonomy.

             Plant Families include groups of genera with some similar characteristics. Examples are Roses

(family Rosaceae), Orchids (family Orchidaceae), and Grasses (family Gramineae or Poaceae).

Again, flower and fruit differences are often used to define families. Families are best learned by

becoming familiar with some plants in the family.

             The genus (plural = genera) is one of the oldest names in use. Many people know

Oak (genus Quercus), Maple (genus Acer), Birch (genus Betul\a), Willow (genus Salix), Tulip

(genus Tulipa), and even Rhododendron (genus Rhododendron). This is also true in other parts

of the world.

             The Latinized single words for genera go back to the Swiss botanist Joseph Pitton deTournefort

(1656-1708). He gave the first consistent characterization of genera. The genus is like our last name,

except it is only used once. It is listed before the species and has meaning by itself. Currently,

the Genus name is always capitalized.

             Genera are defined as a group of related species. Generally, genera are unable to be crossed

with other genera, but there are some exceptions, especially in the Rosaceae or Rose family. Similarity

of flowers and fruits are the most stable characteristics for flowering plants. Leaves are often modified

in different environmental conditions. However, with gymnosperms, the form and arrangement of leaves or

needles helps separate pines, spruces, firs, etc.

             Genera include one or more species, but there is no objective criteria for the decision.

The decision is subjective, and some taxonomists prefer larger groups for a genus, while other taxonomists

prefer smaller groups with very closely related species. This lumping or splitting is not a problem if

authors are aware of it and properly cite the synonyms. Some plant genera have very distinct species,

while others may have species that are close and not easily separated.

             Ray, Tournefort and others continued to use multiple word descriptions for species.

Every species in a genus was known by a description of 5-20 or more Latin words.

The Swedish botanist Carolus Linnaeus (Carl von Linne)(1707-1778), was the first to introduce

the concept of binomial names, a genus and a one word species. In his Species Plantarum, published

in 1753, he has the single word species name in the margin after each description. Linnaeus classified

plants, animals, etc. with a hierarchy, starting with the kingdom, then classes, orders, and then genera.

Species names are not capitalized, although in the past proper names and places were capitalized.

             A Species is somewhat difficult to describe. Some species are separated by geographical

barriers. For others, effective transfer of pollen from one plant to another may be impeded in various ways.

Some plants are self sterile, and need pollen from other plants. Other species flower at different times.

Cronquist defines species as the smallest groups that are consistently and persistently distinct,

and distinguishable by ordinary means. Plants should be distinguished by visible characters or features,

or with a 10x hand lens, or at the most, a 20x-40x dissecting microscope. Once you see a feature

under magnification, it is often possible to see it with the naked eye, since you know what you are

looking for. Plant species should be practical. You cannot take a chemistry lab in the field to use

in identifying a specific plant. You can use lab techniques to understand the relationships between

species, but you should not describe species that cannot be identified by visible features. Ferns,

conifers, and flowering plant species need to have more visible characters for identification. Remember,

communication with others is important.

             A typical species is a set of closely related plants that can interbreed with each other, but may

not interbreed with other species. If an occasional cross does occur and viable seed is produced,

the two groups may be called subspecies of a single species.