Cultivars and hybrids of native plants
Back in my ornamental gardening days, I followed the advice of so many garden books: Choose cultivars. I just wanted the latest, greatest, most elaborate flowers I could find.
Now, as a habitat gardener, I try to avoid them.
What's a cultivar?
According to William Cullina, "A cultivar is a clone or seed strain selected for a particular trait or traits."
By choosing cultivars, gardeners know exactly what they're getting, without the variation possible in the plain species. You'll find many articles and nurseries singing their praises.
Cultivars let gardeners design their gardens for that "wow" factor, much like an interior designer decorates their living rooms.
BUT my living room is not a living thing; my garden is.
But another reason cultivars are promoted has nothing to do with their gardenworthiness: they're simply more profitable for the company that introduces them. They own them and can charge more for them, even if they're not very different from the species (and many of them aren't).
NOTE: Cultivars are beginning to be referred to as "nativars," trading off people's growing interest in native plants.
Don't be fooled! A "nativar" is a cultivar of a native, but with a more palatable name.
What's a hybrid?
A hybrid plant is created by crossing two species, which results in some characteristics of each parent and perhaps resulting in quite a different creation.
Man-made hybrids are written with the genus name, then "x", then its given name enclosed with single quotes. For example, Coreopsis x 'Moonbeam', which is a cultivar of hybrid origin.
(See more about scientific terminology.)
Interestingly, hybrids can occur naturally, as is the case with my apple serviceberry. Apple serviceberry is a naturally-occurring hybrid of Allegheny serviceberry (Amelanchier laevis) and downy serviceberry (A. arborea). The resulting apple serviceberry is written as A. x grandiflora.
Except for these naturally-occurring hybrids, I don't choose hybrids at all.
Why I avoid cultivars
There are two reasons we try to avoid cultivars, though sometimes that's all that's readily available—at least until there are more nurseries specializing in natives.
Habitat properties aren't always there
I changed my ideas about cultivars when we bought a cultivar of a serviceberry, Amelanchier canadensis 'Glenform.'
We bought it because at the time (more than ten years ago), there weren't many native shrubs available. We've been very disappointed to see that it produces very few berries. And of course, berries is what we bought this plant for! What a loss for birds!
I assume this cultivar was introduced because of it's smaller than A. canadensis. This is the case for many if not most cultivars. They're selected because of some characteristic without regard to whether it retains the habitat properties that originally made them valuable for wildlife.
We've since cut it down.
An aster cultivar
I bought this cultivar of a native at a big-box store on a whim, since it was the end of the season at deep discount. Since my aster species tend to be quite tall, I thought this might be a good thing to experiment with as a possible recommendation to people looking for a more conventional landscape.
BUT when I observed it the first fall, I noticed that bees were busy at all the surrounding aster species, but weren't at all interested in this garden ornament. Another case of "decorating" our land rather than making it part of the ecosystem. What a loss for the bees!
If we want shorter asters, we simply prune back the tall species asters in June. We're experimenting with how drastically we can prune and still have them flourish.
Basically, if a particular species is too big for our property, the best alternative is to find a different plant that fits. Lots of smaller native plants exist!
They limit genetic diversity
When a nativar is first selected, who knows where that particular genotype came from? It's possible that that particular genotype will meet the needs of insects and other wildlife, but it's likely it won't be acceptable to all (and some research is finding this is the case). Certainly it's not going to equal the value of plants produced locally from locally-collected seed that is open-pollinated—the plants with which wildlife co-evolved.
Also, diseases or pests appear (often due to importing non-native plants) that wipe out whole populations of particular species. Think about chestnut blight, Dutch elm disease, and gypsy moths in the past and currently hemlock wooly adelgid, emerald ash borer, and viburnum leaf beetle among many others.
When every plant of a particular species are the same genetically, we lose the opportunity to have individual plants with unique variations survive and deal with new challenges.
Climate change is a huge challenge that cries out for genetic diversity. Our future depends on having some plants that will survive in a changed and changing environment.
All in all, we'd prefer to take our chances on choosing plants that perhaps result in a less than ornamentally "perfect" and not totally predictable outcomes but which maintain genetic diversity for the future.
Sometimes we've chosen cultivars
There's one situation where we have chosen cultivars, though this has happened infrequently.
We chose to buy a cultivar of flowering dogwood (Cornus florida 'Cherokee Princess') because it is supposed to be resistant to anthracnose, a common affliction. (There is some indications that this disease was brought to this country by the non-native kousa dogwood.) So far, it seems to be doing well.
Was this an appropriate choice? Perhaps by planting a few non-cultivars, we'd chance upon one that was resistant. Something we'll consider as a general principle in the future.
The bottom line: Open-pollinated, local genotype species are beneficial; nativars may or may not be. The obvious choice for anyone concerned about the world we're leaving our children is to favor true natives.