Landscape
And
Nursery
Dialog
Mary Ann Rose
Commercial Landscape
& Nursery Specialist
The Ohio State UniversityJune, 1998
A Rose by any other Nameā - Reviewing Plant Nomenclature
Keywords: nursery, landscape, business management
S everal plant materials programs are presented each year at the OSU Nursery Short Course, and when the evaluation sheets come back to us, this comment always crops up: "Why can't the speakers use the common names??" Fortunately it's a small minority of attendees who feel this way. Anyone in the industry who regularly deals with horticultural professionals from other countries and even other states understands the importance of maintaining a consistent code of plant nomenclature. Common names do not satisfy the need to describe plants with precision, because common names change from place to place.
The most basic unit of classifying plants is the species. The species is a concept that defies definition. Probably the 'species' is as much a creation of man's need to conquer and classify as it is a real biological distinction between organisms. Philosophy aside, we generally think of a species as a distinct group of plants with similar, heritable traits.
In the eighteenth century, Linnaeus presented the binomial system of naming species to the scientific community. All plant and animal species would henceforth be given a binomial name (e.g. Acer rubrum) consisting of a genus name (e.g. Acer, a group of species with similar characteristics) and a specific epithet (e.g. rubrum). Most of us will call the 'specific epithet' the 'species name', but this is inaccurate since the species is truly defined by the binomial. Binomials are referred to as 'Latin names' because they are derived from Latin. Latin name are italicized, the genus always capitalized. Sometimes they will appear with the authority, which indicates the person that named the plant. For example, Juniperus virginiana L. was named by Linnaeus.
Most horticulture professionals are familiar with the binomial classification described above, but get lost on the finer points of nomenclature; hence a brief review follows.
A variety is a group of naturally occurring plants within a species that exhibit specific heritable traits, but are not different enough to be considered a separate species. For example, flower color in a variety may be different from other plants in the same species. The thornless honeylocust (Gleditsia triacanthos var. inermis) is an example of a true variety within the species Gleditsia triacanthos.
Many people will use the terms variety and cultivar interchangeably, but they are distinct. A cultivar is a group of plants with definable characteristics that originated in cultivation or through selection by man. Cultivars are usually are capitalized and appear in quotes (Tilia cordata 'Greenspire'), but sometimes are written like this without quotes: Tilia cordata cv. Greenspire. It's possible to have a cultivar of a variety: Viburnum plicatum var. tomentosum 'Mariesii.'
The fact that a cultivar name has been bestowed on a group of plants only means that a human being thinks they have unique characteristics of horticultural importance. It does not mean they are clones. A clone is originally derived from a single plant and must be asexually propagated. Many, but not all cultivars of woody plants are clones. Cultivars also may be seed-propagated. A line is a genetically homogeneous group that can maintain the desired traits through seed propagation. Lines in turn may be used to create hybrids. Hybrids do not come true from seed, rather hybrid seed must be produced for each growing season by crossing parental lines. Cultivars may be selected from both lines and hybrids. Hybrid cultivars of annual flowers and vegetables are common.
Systems of classifying plants have been heavily dependent on fruit and flowers and other obvious anatomical characteristics until this century. Today cutting edge scientific methods are being employed in taxonomy to reveal evolutionary relationships; as a result, many of the classification systems of the past have been declared arbitrary and scientists are replacing them with systems based on evolution. What this means to the horticulturist is that the plant you knew for years as Chrysanthemum x morifolium is now Dendranthema x grandiflorum. In fact, the genus Chrysanthemum, once containing over 200 species, now contains three! Frustrated horticulturists are lining up to say they'd rather fight than switch.
The other gripe we hear a lot of in the industry concerns the increasing number of trademark names. A trademark name carries no taxonomic weight, so these names are accompanied by what Michael Dirr calls 'nonsense cultivar names.' Nonsense, I presume, because nobody really uses them and they are odd. My guess is the developer of the trademark name does not want you to remember or use the cultivar name. For example, 'Sutyzam' is the cultivar name for the trademark 'Sugar Tyme' crabapple. Anyone who shows consistent use of a name for a plant with the trademark symbol (TM) in superscript has the sole right to use that name. Anyone wishing to grow and sell the trademarked plant must pay royalties and conform to a licensing agreement. Registered trademarks are designated by '®' and have been filed with the US government's Office of Patent and Trademarks. Apparently the use of trademarks is a successful and profitable marketing trend that we can expect to see grow in the future.
