Stamford CT, August 25, 2011
To continue last month’s discussion on determining what’s native, etc., I’ve saved the most frustrating part of this discussion for last: nativars. “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.
Here’s the issue: why not just buy that pretty wildflower being sold at your local nursery? That species is native to your area; however, chances are that the local nursery’s stock does not come from your area, but so what? It’s good to support the local nursery’s effort to offer sort-of-natives, right? Meanwhile, it can be much more time consuming and expensive to acquire local genotype natives from a specialty grower, and their plant lists can be a bit limited. Further, just how local are the specialty nurseries anyway?
Accordingly, the suggestion is often made that the next best thing is a nativar. But is it?
To review the basics: The local herbivores, including most of the native insects which feed the birds, fish, and toads, etc., often can not recognize foreign plants as food. At best, foreign ornamental plants are taking up space that could support useful plants which would feed the native wildlife and/or you. At worst, these plants become invasive, crowding out the beneficial native plants.
In a place like Fairfield County, where I live, there is so little uncultivated space left and so much of that is overrun by white-tailed deer, that we need to make every inch of yard count.
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? Perhaps none; perhaps a lot. We have all seen how related species that bloom at the same time can interbred. For example, the London plane tree is said to be a spontaneous cross of the American and Asian sycamores left to their own devices in England’s Kew Gardens.
This can also happen with local genotypes and nativars. 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.
When I first heard this, I was shocked and depressed – so much work trying to educate people to plant native and now, come to find out, if the plants they were putting in aren’t the real McCoy, maybe they were doing more harm than good! How are we going to get the average gardener to understand local genotype? I didn’t want to believe it but a botanist friend of mine, the amazing E. C. Morgan, started digging up studies. See for example, Problems Associated With The Introduction of Non-Native Genotypes On NRS Reserves, Committee to evaluate introduction of exotic genotypes into UC Reserves by John Endler, Chair Susan Mazer, Mike Williams, Cristina Sandoval, Wayne Ferren.
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.
But what to do when acquiring the local genotype isn’t practical? Right now, as far as I can see, it’s a crap shoot. This is an area that needs more study and discussion particularly at the lay level. After all, we lay people are doing most of the planting and most of the educating of the general public, so are most in need of whatever guidance the botany community can provide.
I, frankly, don’t know the best answer, if there is one. Today, I would not think twice about planting nursery-stock blueberries in the average urban garden – great fall color, delicious fruit for the birds, and, perhaps, a local insect host. Further, any blueberry is so much better (I hope) than the winged euonymus (firebush) which is often planted in my area for similar fall color and which has become our dominant invasive understory shrub.
When it comes to the suburbs, however, much of the suburbs in my area is now represented by giant houses on one-acre or larger plots smack in the middle of the now-fragmented forest, often abutting a wetland. In these suburban areas, whatever is planted is being injected directly into what’s left of the local ecology. In these areas, I would be very careful, for example, of getting a non-local genotype blueberry anywhere near our treasured local subspecies, the swamp highbush blueberry.
At this time, the best I can say is don’t let the ambiguity and lack of definite “rights and wrongs” stop you; we need to keep trying until we get it right. Each local native plant and animal that we save matters. Just be aware of the issue and don’t assume that nativars are safe and useful – get the local genotype if you can. Over time, hopefully, the plants nurseries that offer local genotypes will expand to the point where this is less of an issue.
Additional reading: Vincent Vizachero’s Native Cultivars – Good, Bad, and Ugly
All readers with thoughts on this critical subject: please chime in. Please leave a comment and join the discussion. We can’t wait to hear from you.
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