The most recent issue of the Wild Ones bi-monthly journal arrived the other day, featuring a big page one article on ‘Nativars’, or cultivars of native species. I’m a member of Wild Ones, which seeks to promote the use of native plants. The article lays out the organization’s recently adopted stance regarding these plants, which is that their use should be discouraged in the garden and avoided entirely in restorations.
Nativars can be naturally occurring varieties or the result of breeding programs. They are selected for desirable traits, such as compact habit, disease resistance, or flower color or shape. For example, New England Aster (Symphyotrichum novae-angliae) is normally 4-6′ tall but the nativar ‘Purple Dome’ grows to only about 2′.
Most (though not all) nativars for sale are produced as clones through cuttings or tissue culture – which is to say they are exact genetic duplicates of the original plant.
I can understand about restorations, but I think the approach Wild Ones has taken to ‘nativars’ in home landscapes is counterproductive, though not entirely without merit. Concerns about nativars seem to fall into two general areas: 1) loss of genetic diversity, and 2) loss of plant traits most valuable to wildlife.
Genetic Diversity. If every individual of a given plant species is a clone, then of course genetic variation is lost. This severely compromises a species’ ability to adapt to new diseases or other threats. We have seen this play out in devastating blights of potatoes, bananas, and other agricultural crops.
On the other hand, I suspect that you will not find the same kind of dominance by one variety in the garden as often occurs on the farm. For example, you can find dozens of nativars of New England Aster or of Bee Balm (Monarda didyma).
What’s more, non-sterile nativars in the garden will cross breed with other nativars and with the straight species. Nativars and other cultivars frequently do not “grow true” from seed set in the garden, meaning that the offspring are not simply duplicates of the parents.
And let’s not forget that the only hope of saving some native species, such as the American Elm (Ulmus americana) and American Chestnut (Castanea dentata), lies in disease-resistant cultivars created through scientific breeding programs.
Wildlife Benefit. The nativar trait that is desirable to gardeners may render a plant less beneficial to wildlife. Some gardeners love double blooms (I don’t), but double blooms make life harder for foraging pollinators. What’s more, the genetic tradeoffs involved in achieving a more benign trait can result in the loss of characteristics valuable to wildlife, but this is harder to detect.
According to Douglas Tallamy’s Bringing Nature Home, native plants’ most ecologically valuable trait consists of foliage with a leaf chemistry that is palatable to insects (who tend to be very picky about their leaves – who knew?). A diverse and healthy insect population is essential to a healthier environment, including bird populations as well as keeping destructive insects within bounds.
Tallamy, an entomologyst, has found that exotic plants support less insect life, and so he is a proponent of natives. In his book he applauds nativars as a way to expand use of natives by the gardening public, though the Wild Ones article quotes him expressing a preference for straight species.
Certainly if a nativar boasts that it is insect resistant, that is a pretty good sign that it has reduced wildlife value. But there doesn’t seem to be any scientific evidence that in general nativars provide less wildlife value than straight species native plants.
A Continuum of Practices. Which leads me to a more general reaction to the Wild Ones article. It seems to me there is a continuum of environmentally responsible gardening practices. Most gardeners would like to be responsible but many lack information.
The mission of educational organizations like Wild Ones should be to nudge as many gardeners as possible up the continuum towards more sustainable methods. However, this requires recognizing that most people are more comfortable with incremental changes in their habits. If the choice seems to be between purity and the status quo, very few will opt for purity.
Advocates also need to recognize that most people garden primarily for aesthetic satisfaction, and not simply to save the environment. So putting on a frowny face of disapproval because someone plants Joe Pye Weed ‘Gateway’ rather than the straight species is not going to accomplish much. ‘Gateway’ is somewhat more compact and has a richer color – but living with ‘Gateway’ may expand a gardener’s appreciation of more wild straight species natives (making it a gateway plant! Ha!).
I think a more productive educational message would tout the benefits of incorporating straight species plants in the garden, rather than arguing for straight species exclusively. Frankly, the same could be said for native plants in general. As much as I love natives, they are not now nor will they ever be the only plants in my garden.
Until we can establish a Commissar of Garden Plants (and I’m definitely available if that position is created!), native plant advocates should focus on promoting the incremental changes most likely to take hold among rank and file gardeners.
What do you think about using straight species versus nativars or cultivars? Or do you not really care about the origin of a plant as long as it is culturally well-adapted?