Plant Descriptions

The base classification unit in taxonomy is the Species. In general terms the Species definition has gradually moved from having a basis in physical characteristics towards one in genetic characteristics. The general definition of a species is – “The largest group of individual organisms in which two individuals of appropriate sex or mating type can produce fertile offspring the same as themselves”. When first described from a physical specimen new species are given binomial (two part) names. While these names appear to be in Latin, they are often a combination of Latin, Greek and made-up words in a Latin / Greek style.

The first part of the name is the Genus, it is always a noun and always Capitalised and italicised. You could think of this as the plants surname, there are often more than one plant in a genus.

The second part of the name is the “name” of the species or its “epithet”, sometimes its known as the ‘specific epithet’. It is always an adjective, lower case and lower case and italicised, it is often descriptive of the plant’s appearance, colour, habitat, country of origin or discoverer.

As knowledge develops, particularly through DNA analysis plants are occasional reclassified, and therefore renamed, typically this changes the Genus but not the specific epithet. In science the newly accepted name becomes the current species name and older versions are relegated to synonyms of the same plant. In Horticulture it can take some time for the current name to filter down into common use. In Our catalogue we use the most recent accepted name but provide recent synonyms. On occasions you may see references that apply to all species within a Genus, this is denoted by the genus name being followed by the lower case, italicised term “ssp.” as in Genus ssp.

For more on Nomenclature & horticultural Latin please see our Latin Lexicon.

Many Thanks to Dr Marie Addyman for the use of her notes to improve this section.

Subspecies

The Subspecies rank comes directly below Species. They are primarily denoted by geography and represent one or more distinct populations of individuals living in different locations within the overall geographic range and which differ in physical characteristics. As members of the same species, they are often able to interbreed, although some offspring may be sterile, and this is unlikely to happen in nature due to the distance between locations. This ability to interbreed can be useful in horticulture. The nomenclature used for subspecies is the addition of the lowercase, uncapitalised “subspecies.” or is abbreviated forms “subsp.” or “ssp.” followed by the lowercase, uncapitalised, italicised subspecific epithet (the specific name of the subspecies). E.G Genus specific ssp. subspecific.

Variety

The Variety rank also comes directly below Species. This rank applies only to wild or naturally occurring plants. They are primarily denoted a by difference in physical characteristics that is consistent across the geographical range of the species and do not represent distinct populations of individuals. Like subspecies they are often able to interbreed, although some offspring may be sterile. This ability to interbreed can be useful in horticulture. The nomenclature used for varieties is like that for subspecies. It is the addition of the lowercase, uncapitalised “variety.” or its abbreviated forms “var.” or “v.” followed by the lowercase, uncapitalised, italicised intraspecific epithet (the specific name of the variety). E.G Genus specific var. intraspecific.

Cultivar

The Cultivar rank also comes directly below Species. Cultivar is short for Cultivated Variety, this rank applies mainly to plants that have been intentionally bred by humans for specific traits such as fruit yield or flower shape and are maintained as distinct types by vegetative propogation. Less often they may arise naturally, or as “Sports” (chance genetic mutations) in part of a plant, such as a shoot. The nomenclature used for Cultivars is the addition of the lowercase, capitalised ‘Cultivar Epithet’ which is enclosed in single quotation marks. E.G Genus specific ‘Cultivar Epithet’. The vast majority of plants sold through commercial horticulture are cultivars.

Form

The Form rank comes directly below Variety and so applies only to wild or naturally occurring plants. They are primarily denoted a by minor but noticeable differences in physical characteristics and do not represent distinct related populations of individuals. An example would be a white flowered form of a plant that usually has purple flowers like Foxglove. The nomenclature used for Forms is like that for subspecies. It is the addition of the lowercase, uncapitalised “forma.” or its abbreviated form “f.” followed by the lowercase, uncapitalised, italicised intraspecific epithet (the specific name of the Form). E.G Genus specific f. intraspecific.

Hybrid

In biology a hybrid is the offspring of two organisms of differing varieties, species, or genera via sexual reproduction. They are not always intermediates between parents, sometimes sterile, and often display “hybrid vigour”. Plants hybridize more easily than animals. They also exhibit polyploidy (many copies of chromosomes) which can lead to increased chances of fertile hybrids or even the generation of entirely new species. Hybrids can occasionally occur in nature but can only do so where compatible plants share a common geographical location, flowering period, or pollinator. Hybrids between Orders or Families are very rare, from Species level down hybrids are more common. In horticulture many of these barriers can be overcome, often intentionally. F1 hybrids are single (first) cross hybrids between Species or Varieties that breed true. F1 plants commonly exhibit features from both parents, and usually have hybrid vigour. F1 plants may be sterile or fertile but if fertile do not breed true to type.

Hybrids do not have their own taxonomic class but are named according to taxonomic principals. They are denoted by a name containing a non-italicised “×”. If the sex of the parents is known then the format is Genera female × Genera male, if the sex of the individual parent is not known then the names arranged in alphabetic order of the Specific e.g. Genera aspecific × Genera zspecific, more often you will see a new specific used for the hybrid e.g. Genera × newspecific.