What’s in a Name?
Definition of Cultivar
The word cultivar comes from the combination of the term ‘cultivated variety’, meaning plants that have been cultivated and bred by humans. They are created by engineering specific desirable traits such as colour, form, hardiness or resistance to pest and disease. These plants are continually bred with the carefully selected traits until the plants display the desired attributes consistently. Article 2.2 of the International Code of Nomenclature for Cultivated Plants (ICNCP or “Cultivated Plant Code”) defines a cultivar as “an assemblage of plants that has been selected for a particular attribute or combination of attributes, and that is clearly distinct, uniform, and stable in its characteristics and that, when propagated by appropriate means, retains those characteristics”.
How do Cultivars originate?
Some cultivars may begin as a sport or mutation from its wild ancestor, or may be a hybrid intentionally crossed from two differing parent plants. In order for the the selected traits to continue into the offspring, essentially cloning their parents, they typically require asexual or vegetative propagation. This means growing new plants by cuttings, grafting, or tissue culture. Sexual propagation, or plants grown from seed, will typically result in variably different outcomes than those of their cultivated parents. This process isn’t consistent or reliable for growers, therefore those plants will never be labeled or sold under the parent’s cultivar name.
Cultivar vs. “Variety”
Cultivars should not be confused with variety. A variety is a naturally occurring version of a plant that has been propagated for its genetic characteristics. Sometimes a different form of a particular species will be considered a variety. It is when these specific attributes are artificially selected and bred by humans that they become a named cultivar. One way to differentiate a cultivar from a variety is to look at the scientific name it has been given. A cultivated plant name will have a capitalized first letter and the word will never be italicized. The cultivar name will be surrounded by single quotation marks, never double, or may have the abbreviation cv. (cultivar). For example, Acer saccharum ‘Columnare’ is a cultivated sugar maple, which was bred for its columnar habit. The scientific name for a variety is always written in lowercase and italics, and may have the abbreviation var. (variety) preceding it. For example, a naturally occuring white flowering Redbud is named Cercis canadensis var. alba. A similar tree, the Royal White Redbud, which has been bred for its hardiness, is named Cercis canadensis var. alba ‘Royal White’.
“Nativar” = Native Cultivar
To add to this name confusion, the term “nativar” is becoming more popular and widely used in gardening information and promotional materials. A nativar is another combination of terms “native cultivar”, meaning a cultivated plant bred from a native species. Like all cultivars, these plants are the result of artificial selections bred and maintained by humans. As such, they must be cloned in order to propagate, passing on the exact same genetics to their progeny. This means that they don’t contribute to genetic diversity the way locally sourced and adapted native plants do. The genetic diversity found in straight species native plant populations largely contributes to their survival and persistence in our rapidly changing climate.
More terms to describe species variations:
(Click table for PDF)
The Down-Side of Cultivars / Nativars
Native plant populations also function as the foundation to a healthy ecosystem and the loss of this genetic diversity can lead to an increased vulnerability to pests and disease. Pollinators and other wildlife rely on our native species, and unfortunately, cultivars and nativars can cause a disruption to the balance of the natural system. For example, a sterile (does not produce seed) maple cultivar will greatly reduce the amount of pollen and nectar produced and will not provide food for our seed-eating birds. With cultivated changes in habit, leaf colour and sterility, the concern remains as to whether these cultivars provide the same support system to our native wildlife, bees, butterflies and caterpillars especially. There is also the risk of cultivars cross-breeding with the surrounding native plant populations. Studies have shown this can result in a loss of our wild species, further impacting the wildlife that rely on them.
Why doesn’t Maple Leaves Forever accept cultivars / nativars for our Rebate program?
Native maples, grown from locally sourced seed are ideal for enhancing biodiversity in our landscape and supporting a healthy ecosystem. The more diversity within a species, the more they are able to adapt to climate change, build resiliency, and become less susceptible to pest and disease issues. This is the leading principle as to why Maple Leaves Forever does not accept rebate applications for any cultivars, varieties, or nativars of our native maple species.
For further reading: