A Primer on Plant Nomenclature 

Audrey Hillman
Adams County Master Gardener

Have you ever wondered how it is that we name our plants? Most of us are not comfortable with Latin, have difficulty remembering and pronouncing it, and refer to our plants by their common names. The problem is that common names are usually applicable only in a certain geographical area and so are not accurate universally.

Many times plant labels. catalogs and seed packets have the Latin names many times they don't. It can all be somewhat confusing. So let's start with a little history.

Classification

Mankind has studied plants throughout the ages. Plants were and are essential to survival. Every civilization had its own system of classification. Then Columbus and other explorers made discoveries of new lands and new plants. Chaos ensued and from the disorganization came Species Plantarum. Written in 1753 by Swedish botanist Carl Von Linne, it ushered the system two used today of binomial - two names - nomenclature. Linne, aka Linnaeus, based his system upon the flowers of the plant, specifically the reproductive parts of the flower. The language used was Latin,. which was the scientific language of the day

The Linnaeus system of classification is as follows: Kingdom, Division, Class, Order, Family, Genus, Species, Subspecies, Variety and Family. The rules for the naming of these groups are governed by an internationally accepted Code of Botanical Nomenclature. However, not every plant falls neatly into every category. There is often disagreement among botanists as to what should go where.

Family, genus, species

For those interested in gardening, the family grouping is usually where the classification process takes on significance. A family is a group of plants whose members resemble one another in several respects. An example would be the lily family' which is composed of over 200 genra. A Genus - plural genra - is made up of closely related and similar plant species.

A species is a group of plants that are similar in a number of ways. They are interfertile and breed true in most cases, i.e., a ugar maple seed grows into a ugar maple.

When a plant's name is written the first word is the name of the genus that the plant belongs in. It is always capitalized. As all plants have two names the second part is referred to as the specific epithet and is not capitalized. Both words together are called the species name of the plant.

Subspecies and variety

A subspecies is a group of plants that is different from others of the same species in one or more ways and usually occurs in a certain geographical area. An example of a subspecies would be that of a plant that always has white flowers except near a particular mountain where some of the flowers are pink.

A variety would be the same thing only there is no geographical distinction. That pink flower would be part of the population throughout the whole range. Varity is abbreviated var. And the plant name would be written var. Pink. Both subspecies and varieties breed true and occur naturally.

Cultivar

Cultivar, a new term only recently invented, is used to identify groups of plants that do not occur naturally and are maintained by cultivation. Cultivar is abbreviated cv or is set off by single quotes, e.g., _____ ______ cv. ______.

So then what does it mean when you use an x' between two names? The x' indicates that the plant is a hybrid. Two species within a genus grouping have been crossed. The genus names remains, followed by the x', followed by the specific epithet. An example would be Magnolia x loebneri, a cross between a Magnolia and a Magnolia stellata.

This spring I purchased a packet of seeds labeled cardinal climber Cypress Vine annual vine. I planted them, hoping that is would be a Cypress Vine, Ipomoea quamoclit. As the seeds germinated, it became apparent what I had was Cardinal Climber Ipomoea xmultifida. Both plants are similar. Ipomoea quamocilt is one of the parents of Ipomoea x multifida. While I still have red tubular flowers for the hummingbirds, I would have like the other foliage. Proper nomenclature would have been helpful in helping me before I planted them. It does make a difference.

Read other gardening articles by Audrey Hillman

Read Audrey husband's: An amateur's guide to plant nomenclature