Terminology & Nomenclature

Plant taxonomy attempts to identify and classify every plant in relation to all other plants by close examination of the plant's individual characteristics. However, taxonomy is a science that changes as new technologies allow for the examination of plants at microscopic — even molecular — levels, sometimes resulting in renaming and reclassification. A plant's taxonomy leads to a specific name that is accepted worldwide. Botanical nomenclature is based on a set of rules established by the Swedish botanist Carolus Linnaeus in 1753 and much of his structure is still in place. The advent of DNA analysis in the late 20th Century has resulted in many plants being reclassified as scientists learn more about how they are related to each other.

Genus and species

To identify a conifer (or any living thing) you start with its genus, say Abies, for a fir tree. Genera are then further divided into species, for example, alba (for its unusually white wood) which now makes the plant name a binomial, i.e. composed of two words. Abies alba is the binomial for the European silver fir. (Binomials are in Latin or Greek and always italicized.) All naturally-occurring plants are binomials, and are sometimes referred to as 'species plants', because their description generally ends with their species name. Some naturally occurring plants can be further classified as variations (abbreviated to var.) or subspecies (abbreviated to ssp.) Variety means that the plant sometimes exhibits a particular form or color, but not in a marked enough manner to designate it more exactly. A subspecies of a plant is one that displays slightly different characteristics in a specific part of its native range. It is worth noting that in the world of conifers, virtually all species plants are trees and virtually all of them grow to be very tall and/or large, making them inappropriate choices for most home landscapes and gardens.


Enter the Cultivar! Cultivars, an abbreviation of 'cultivated varieties' are what turn a well adjusted gardener into a conifer collector who often becomes afflicted with ACS (Addicted Conifer Syndrome.) Cultivars are generally (although not always) slower-growing and showier than their native forebears. Cultivars are freaks of nature whereby a typically formed plant (what we've referred to as a species tree) either develops a branch with characteristics unlike that of its parent or the whole plant begins to morph into something different. If this aberration (when a mutation, it is called a "sport" or "witch's broom") is spotted by a knowledgeable plant person who recognizes it as having attractive cultural properties, it is propagated. In the example of Abies alba above, sometime in the 19th century in Germany, an Abies alba spawned a unique columnar-shaped seedling that was shown to be stable (meaning that it maintained its distinctive characteristics through subsequent generations). It was given the cultivar name 'Pyramidalis.' All descendants that retained this unique shape over the centuries have been called Abies alba 'Pyramidalis'. When all three levels in the hierarchy are used in the plant's name it is called a trinomial.

Sometimes cultivars result from chance seedlings that exhibit different form, texture or color than their parents. These are most commonly found at big nurseries that produce hundreds of thousands of seedlings at a time. In the beds of tiny plants, it is not difficult to pick out the seedlings that are different colored or have different forms. The difficult part is growing them on, to determine if the notable characteristic remains true through subsequent generations.

Cultivars can also be the result of selective breeding by horticultural professionals, in most cases crossing seed from two species in the same genus, but there are a few cross-genera conifers as well. Some of the most well-known, however were originally thought to be cross-genera, but DNA analysis and reclassification of their parents has them now firmly in the inter-generic category. Leyland cypress, for example, was introduced as a cross-generic product of Cupressus macrocarpa and Chamaecyparis nootkatensis. Taxonomists reclassified Chamaecyparis nootkatensis to Cupressus nootkatensis and suddenly, Leyland cypress finds that it is no longer a cross-genus hybrid!

If the conifer continues to hold its uncharacteristic form over multiple generations and time, the owner or propagator of the new plant can give it a name and submit it to the United States Conifer Registrar. If accepted, there is now a new cultivar which can be patented for 20 years, thereby creating the possibility of revenue for the original propagator or grower, who produces it in quantity for the market. Many ACS members have discovered witch's brooms that are now being sold in specialty nurseries across the country, as well as overseas. The ACS Conifer Database was designed to facilitate searches by knowledgeable conifer enthusiasts but also as an educational tool to help newcomers understand the hierarchy of conifers, so as to better understand the breadth and depth of this horticultural specialty.

Editor’s Note: Want to learn more about Conifers? Become a member of the American Conifer Society and receive the ConiferQuarterly, with articles written by some of the most respected plantsmen and women in the country. You will also be eligible for discounts from many nurseries and help to promote the development, propagation and conservation of conifers around the world. JOIN HERE!