Hints for Understanding Scientific Plant Names
In Nursery Catalogs and on Plant Labels
Scientific Naming of Plants
There are two general types of naming systems for plants: common names and scientific names. Scientific names also are called Latinized (or "Latin") names. Scientific names are organized in a system whereby a species is described with a genus name followed by a specific epithet. The genus Ilex is the holly genus. The genus Ilex includes many species, each with its own specific epithet following the genus name: for example, Ilex aquifolium (English holly), Ilex opaca (American holly), Ilex serrata (Japanese winterberry), and Ilex verticillata (winterberry - native to eastern North America ).
Some plants have naturally-occurring sub-species or varieties. Seedlings of these natural sub-species and varieties will exhibit the same types of distinguishing characteristics as are found in their parents. Natural sub-species and varieties tend to grow where they are reproductively isolated. For example, they may grow in different parts of a plant species' total range or they may be found in different habitat types. Or, they may have characteristics (such as different blooming times) that prevent them from cross-breeding with plants of the typical genus and species.
The names of sub-species and natural varieties are written beginning with the genus and species followed by the abbreviation ssp. or var. (some use subsp. or v.) before the Latinized name of the subspecies or variety. Ilex verticillata var. fastigiata is an example of a naturally-occurring variety of winterberry. It is found in wet sands near the sea from Nova Scotia to Long Island. Note that sometimes in the nursery industry the ssp. or var. is left out of the plant name.
A cultivar is a cultivated variety (may be called a horticultural variety). Cultivars are maintained via human intervention. Some cultivars were developed by taking a unique individual of a species (or even an odd branch of an individual) and reproducing it through cuttings, grafting, or tissue culture (all resulting in plants genetically identical to the parent). Selective breeding is used to create cultivars that are reproduced by seeds. The seedlings continue to have the desired distinguishing characteristics because for each generation, humans control which individuals are involved in reproduction. Some nursery people use the term "variety" rather than "cultivar" to refer to cultivars reproduced by selective breeding. A plant label that includes part of the name written in single quotes indicates a cultivar. For example, Ilex aquifolium "Lily Gold" is a cultivar of English holly that has irregular, gold-edged leaves. Another way to indicate this cultivar is Ilex aquifolium cv. Lily Gold. Confusingly, on some printed plant labels, cultivars lack the quotes but fail to include the abbreviation cv. making it difficult to distinguish them from natural varieties improperly lacking the var. in the label name. Hybrids A hybrid is a plant that is a cross between two species. Sometimes this occurs in nature. Other times crosses are made intentionally. Plants that are named hybrids have the genus name followed by an X (indicating species have been crossed) followed by the name given to the result of the cross. For example, the named hybrid, Ilex X koehneana, is cross between Ilex aquifolium and Ilex latifolia. If the cross had not been given a name, it would have been written Ilex aquifolium X latifolia. When two species are crossed, not every offspring is the same. Sometimes, certain offspring chosen to be cultivars are then reproduced through cuttings. For example, "Ruby" and "Jade" are two cultivars of the Ilex X koehneana hybrid. The Ilex hybrid "Sparkleberry" is a cultivar of the unnamed cross between Ilex verticillata and Ilex serrata that has long-persisting, brilliant red fruits. With unnamed hybrids, a cultivar plant label might only include the genus and the cultivar name (as in Ilex "Sparkleberry"). From this form of name, buyers can tell only that it is a cultivar of a hybrid (and will not be able to determine the parents unless they happen to have a reference book containing the cultivar's history).