I have always thought it to be practical to describe featured plants species by their botanical or “Latin” names. Common names may be confusing because so many of them are regionally specific. For example, the coast live oak is a completely different species from the Japanese live oak, the Virginia live oak or the Texas live oak; all of which are known as live oaks. However, botanical names are the same everywhere. The rules for naming species are known as “nomenclature”. Although I never understood quite why, botanical names are always italicized or underlined if written to signify that they are Latin words.

All plants are divided into increasingly specific groups, starting with the broadest and eventually reaching the most exclusive. Nomenclature is only concerned with the last two of these classifications; genus and species. It is also often helpful to know the ‘family’, or third classification. Cultivars and varieties are variations within a species. Because cultivars and varieties are not Latin, they are not italicized.

I sometimes find it useful to explain nomenclature as it relates to cars. Two examples may be a silver maple, Acer saccharinum and a Park Avenue by Buick. The silver maple belongs to the family Aceraceae just as the Park Avenue belongs to the family of General Motors. The families are divided into genera (plural for genus) such as Acer and Buick. Species are specific classifications within the genera such as saccharinum and Park Avenue. The silver maple is available as the cultivar ‘Wieri’ just as the Park Avenue is available as the ‘Ultra’. This can all be translated into Acer saccharinum ‘Wieri’ and Buick, Park Avenue ‘Ultra’.

Species are defined as plants which can produce seed among themselves. Some species may appear to be the same, but are divided by genetic incompatibility. Likewise, many varieties and cultivars within a species are very different from each other. Hybrids may occur between species or genera. Placement of an “X” within a botanical name indicates how the cross occurred. For example, Platanus Xacerifolia is a hybrid of two species and XFatshedera lizei is a hybrid of two genera. The “X” is not pronounced and very often not included in spelling.

Varieties are naturally occurring, genetically transmitted variations within a species, such as the ‘Heavenly Blue’ variety of morning glory. Seed from this morning glory will produce plants resembling the distinct variety. Cultivars are variations of a species which can only be produced vegetatively (cloned), such as by cuttings. Cultivars are either too genetically unstable to produce similar seed or unable to produce viable seed; as is common with hybrids. Most cultivars are mutations which produce genetically normal seed.