Mention of cultivars can bring out strong feelings among those in the native plant world. One man told me he wouldn’t come to my nursery because of “too many cultivars.”
Out of our 284 total products, we currently have 19 cultivars; of those, three are wildflowers found growing naturally in the wild and the rest are trees and shrubs, mostly seed grown.
As a native plant nursery, our mission is to encourage the use of plants that provide the greatest benefit to wildlife, and by and large these are seed-grown, straight-species native plants.
Does that mean there is no place for cultivars? The easy answer would be no, but a more accurate answer might be: it
depends.
“One of the biggest concerns people have is that cultivars don’t have as much value as wild-type plants,” says Sam Hoadley, manager of horticultural research at the Mt. Cuba Center in Delaware.
“In some cases cultivars have as much value and even more.”
A Big Umbrella
The term cultivar–basically a form of a native plant–includes everything from a native plant found growing in the wild (sometimes called a nativar) to a laboratory special.
That’s a big umbrella, and it makes it difficult to sort the good from the not-so-good.
If we place cultivars on a spectrum based on human intervention, the low-intervention end would include plants discovered in nature and brought into cultivation because of some feature, or natural mutation, that sets it apart from the crowd.
Since nature selected these plants, “bringing them in and planting them and putting a name on them doesn’t automatically make them bad,” says entomologist Doug Tallamy, in an interview on A Way to Garden. “They’re fine plants when they’re collected that way.”
Seed Grown
Symphyotrichum laeve ‘Bluebird,’ or Bluebird Smooth Aster, was found growing in the wild in Connecticut, and the way to tell it is a cultivar is because of the name attached to the Latin in single quotation marks.
Adding ‘Bluebird’ simply lets people know this native plant has features that differentiate it from the others, Hoadley explains, such as more abundant flowers and foliage that is virtually disease free.
Nudging further on the human intervention spectrum, Carpinus caroliniana ‘Wisconsin Red’ came about after three decades of tagging and collecting seeds from native Ironwood that naturally exhibited exceptional orange-red fall color.
At first maybe one in 50 trees got tagged, explains Paul Schwabe, a horticulturalist at Johnson’s Nursery, which introduced ‘Wisconsin Red.’
Now several of the nursery’s 600 acres are dedicated to growing ‘Wisconsin Red.’ As Schwabe explains, the trick is convincing people this particular cultivar is a native plant.
“They want the pure species,” he says. “We have to holler at them that it’s seed grown.”
Hybrids
Meanwhile, few people would have an issue planting Franklin Tree (Franklinia alatamaha) because there is no single-quote identifier.
Naturalist John Bartram found Franklin Tree growing in the wild in the 1700s, named it after his friend, Benjamin Franklin, and brought seeds from those trees back to his home in Pennsylvania.
The Franklin Tree has since gone extinct in the wild, and so every Franklin Tree available today comes from trees grown from those initial seeds, making Franklin Tree both a native tree and a cultivar.
If Franklin Tree is a cultivar, another native plant, Mountain Gordlinia (x Gordlinia grandiflora) is a cultivar of that cultivar.
The only way you can tell Mountain Gordlinia is a cultivar (in this case a hybrid) is because of the “x” at the beginning of the Latin name.
Mountain Gordlinia was not found growing in the wild; instead, researchers at North Carolina State University created it by mechanically fertilizing Franklin Tree with pollen from another native, Loblolly Bay (Gordonia lasianthus).
Mountain Gordlinia carries traits from both parents, and it is seed grown. Does it offer the same benefits to wildlife as either of its parents? No one has studied it to be sure.
Researchers, however, have studied another seed-grown hybrid, Lobelia ‘Fan Scarlet,’ a cross between two straight species, Lobelia cardinalis and Lobelia siphilitica. While ‘Fan Scarlet’ blooms red, just like Cardinal Flower, it provides just 20 percent of the nectar as its parent.
Garden Decorations
Hitting the higher end of the human intervention spectrum are plants that have been heavily manipulated in the lab and bred for features such as double flowers and unnaturally large blooms.
These flowers offer such little benefit to wildlife they’re essentially no more than garden decorations.
One such plant is a type of Coneflower (Echinace purpurea) called Echinacea ‘Balscblum’ (DOUBLE SCOOP™ Bubblegum). Double Scoop has (as the name implies) double flowers, which is an indication right there that insects will have a hard time accessing any nectar.
Indeed, in trials, researchers at the Mt. Cuba Center found Double Scoop “proved to be unpopular with pollinators attracting an average of only 8 insects in 2018 and 2019.”
Gardens that Work
I have a garden in my front yard composed almost entirely of straight-species native plants. The only cultivar is Fothergilla ‘Mt. Airy,’ which is a naturally occurring hybrid discovered in the wild in Ohio.
There are no other gardens on my street that look anywhere near as wild and full as mine. Some people love it, or at least admire it, and even take photos.
My garden works for me. But I am sympathetic to the homeowner who has a small yard and wants a nice, easy, largely disease-free garden that also feeds and shelters wildlife.
I can understand why this homeowner might choose ‘Claire Grace’ Bee Balm (Monarda fistulosa ‘Claire Grace’), which was among cultivators included in a 2016 study out of the University of Vermont evaluating pollinator preferences among straight-species natives and their closest cultivars.
‘Claire Grace’ was found growing in the wild in Mississippi. Other than being brought into cultivation, no one has changed it. It naturally has sturdier stems than the straight species, slightly darker flowers, bright green foliage and, perhaps most notably, mildew resistance.
In the study, the straight species attracted 877 pollinators while ‘Claire Grace’ pulled in 660, leading the authors to conclude that ‘Claire Grace’ “may be an equivalent substitution” given the benefits of mildew resistance and other factors such as better drought tolerance.
Another cultivar in the study, Veronicastrum virginicum ‘Lavendelturm,’ actually attracted “significantly more” pollinators than the straight species and has a longer bloom time.
Cloning: Elms and Redwoods
While ‘Lavendelturm’ can be grown from seed, at least one nursery I’m familiar with grows this plant using tissue culture. The pollinators still benefit, but genetic diversity suffers.
So maybe this is the best argument for planting only straight-species natives. Or not?
Hoadley, at Mt. Cuba, notes that many nurseries supplying native plants grow popular natives like Pennsylvania Sedge (Carex pensylvanica) from tissue culture because it’s easier and more efficient, and because Carex pensylvanica seed typically have a germination rate of less than 1 percent.
Cloning is still a new science, and there are arguments in both directions.
Initiatives are underway, for example, to clone giant Sequoias and Redwoods. The clones would not only preserve the genetics of these very old trees, but also ensure a future population of giant trees capable of sequestering large amounts of carbon.
On the other hand, especially when considering all the thousands of species of native plants out there, genetic diversity has been shown not only to ensure a robust population but also to protect species from the devastating impacts of invasive pests and other environmental stressors.
There is an American Elm Tree on the National Mall in Washington, D.C., called the Jefferson Elm. For some reason this seed-grown native tree survived Dutch Elm Disease, which destroyed almost every other Elm nationwide.
If you want an Elm tree, it might make sense to plant Ulmus americana ‘Jefferson,’ because the disease is still out there.
The irony is, while genetic diversity initially preserved the Elm, it is now the clones keeping the tree alive because every ‘Jefferson’ available today is genetically identical to the Elm on the National Mall.
About the author
Jennifer Anderson owns Tree Talk Natives, a native tree and plant nursery in Rochester, Mass. A former news reporter, she loves to talk native plants and can be reached at jennifer@treetalknatives.com.
Sources
Dutch Elm Disease. Vermont Invasives.
Echinacea ‘Balscblum’ (DOUBLE SCOOP™ Bubblegum). Mt. Cuba Center.
The Heritage River Birch Township of Bernards Shade Tree Commission, New Jersey.
Hoadley, S. Manager of Horticultural Research, Mt. Cuba Center, interview.
Katanich, D. “Meet the man fighting climate change by cloning the world’s oldest trees.” Euronews via Associated Press. July 17, 2022.
Richardson, M. The Gardener’s Dilemma: Wild-type Plants or Nativars? Wild Seed Project.
Roach, M. How effective are nativars? with Doug Tallamy. A Way to Garden May 28, 2018.
Schwabe, P. Horticulturalist, Johnson’s Nursery, Wisconsin, interview.
White, Annie S. From Nursery to Nature: Are native cultivars as valuable to pollinators as native species? Updated March 1, 2016.
White, Annie S. From Nursery to Nature: Evaluating Native Herbaceous Flowering Plants Versus Native Cultivars for Pollinator Habitat Restoration 2016. University of Vermont.
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