Ask Mr. Smarty Plants

The question of using cultivars of native species is one that many gardeners have been raising recently. They have even created a new term for these plants – nativars. Sue Sweeney has addressed the issue of using nativars in her blog posting, “The Nativar Dilemma.”  She says, “Nativar” is handy term becoming popular to describe “near natives” of various sorts. The term covers any plant that is somewhat closely related to a local native plant but not quite it – usually garden cultivators or hybrids of native plants, including non-local genotypes of native species.

Sweeney writes, "The idea behind nativars is that they may be an acceptable substitute for the local insects and other herbivores that are the essential link in the food chain from plants to omnivores and carnivores. Sometimes the nativar works out, at least for some critters.

However, sometimes it doesn’t. For example, the Connecticut Butterfly Association observed that our adult monarchs wouldn’t touch the pollen of Michigan-grown echinacea – my guess is that a slight difference in chemical composition in the Michigan-genotype prevents our monarchs from recognizing the plant’s pollen as food. Likewise, I have noticed our local pollinators shunning garden cultivars of our native snakeroot.

OK, so not every insect will eat the nativar, what harm? The biggest danger is that the nativar may interbreed with local genotype, destroying and replacing the local genotype. The result might be no ecological harm at all. On the other hand, the interbreeding might turn a local genotype into a plant that the local fauna can not recognize as food, or, worse yet, into an invasive. What can also happen is that the non-local plant is not as hardy as the local stock and the interbreeding weakens the local stock to the point of extinction. So the potential harm is that we lose the local genotype, with a resulting impact on the overall ecology.

Which nativars will fully function, and safely function, in the local environment? The answer would require would require years of study for EACH cultivar. This is obviously not practical so, of course, the best bet is to go for local genotypes." You can read more of Sue Sweeney’s article at http://nativeplantwildlifegarden.com/the-nativar-dilemma/

Debbie Roberts also writes about nativars for the Native Plants and Wildlife Gardens website and asks, “Do nativars, cultivars of native plants, have a place in your wildlife garden?" She says, "They do in mine. And also in many of the gardens I design for my clients. Sometimes, a cultivated variety of a native plant can be easier to combine in a garden. Let’s face it, not everyone has space for purple Joe-Pye weed (Eutrochium purpureum) that can grow to 7′ tall or more in their garden. But they may be able to grow the more compact cultivar ‘Gateway’ (Eupatorium purpureum subsp. maculatum ‘Gateway’). It still reaches heights of 4′ – 5′ though, so compact is clearly a relative term.”

“Nativars, whether open-pollinated or hybridized, are chosen by growers because they offer something new and different – flower or leaf color, a more compact growth habit or improved disease resistance. While they may perform better in your garden, they may not offer all the ecological benefits that straight species plants offer. And relying solely on nativars can mean less genetic diversity in your garden. And depending on what’s ‘new & improved’ about your nativar, it could mean nectar and pollen is not available or that leaf chemistry has been altered so much that they are no longer of any benefit to insects.”

"As wildlife gardeners, we want plants that are colorful, bloom for a long time, look good in our gardens and nourish the local wildlife. The heart of the issue with nativars is whether or not they really are acceptable alternatives to the native species for insects and small animals that feed on plants.  The answer is sometimes, but not always. Frankly, we’ll never know the answer for each and every nativar that seems to popping up on the nursery benches lately.

Fortunately, there is a great deal of research happening now comparing straight species plants to many of their cultivars. Here are some of the studies I’m keeping my eye on. Some are evaluating the vigor and garden-worthiness of nativars while others are evaluating the pollinator value of cultivars."

Vincent Vizachero has also weighed in on the subject with his article, “Native Cultivars – Good, Bad, and Ugly” In his article he describes how cultivars originate and are propagated.