Cultivars — So Many Different Origins
A cultivar is a plant variety— a specific genotype of that species— that has been selected for its unique characteristics and is now sustained by propagation within the nursery industry. This is virtually always done by cloning the parent plant— through division, layering, cutting, grafts, or budding— to preserve the parents' characteristics throughout its offspring. Cultivars vary greatly in their origin. Most simply, they can be produced from the selection of a naturally occurring individual found in the wild. Most cultivars, however, have been created by a careful selective breeding process, often involving many repeated crosses, to produce new qualities of color, form, or other desired traits. Crosses are often done between different species, but are also done between different individuals or variants within a species. And with all things related to human tinkering, there are gradations and multiple possibilities.
The way cultivars are labeled can provide some indication of their origin.
- Interspecies hybrids are usually listed with just their genus and cultivar names, since the parent species names are different. Example: Coreopsis ‘Jethro Tull’ is a cross between Coreopsis auriculata 'Zamfir' and Coreopsis lanceolata 'Early Sunrise.' In this case, the new cultivar has been bred from existing cultivars of two different species!
- A selection with parentage from a single species will typically retain the full species name and add the cultivar name. Example: Coreopsis auriculata ‘Nana.’ This is a dwarf selection of the species; hence the name 'Nana,' often giving to low-growing cultivars, as well as to grandmothers or "nannies."
Be careful— this distinction is not set in stone, and different growers may list the same cultivar in different ways. Oftentimes the true parentage of a cultivar is not widely known, either because it has not been made public by the propagator or because it truly is unknown. Some cultivars originate as chance seedlings in a nursery setting where species may easily hybridize (i.e. cross-pollinate) on their own.
Finally, the more recently coined term nativar simply refers to a cultivar of a native species. But beware of lumping all cultivars into a single category from an ecological standpoint, given the variability by which they are created.