Nature versus nursery?
When it comes to the birds and bees, native plants are typically more valuable than their cultivars
By Nicole Rivard
We know you follow us on social media because you care about animals and the environment, and we know that, like us, you are concerned about the sixth great extinction the world is facing. The good news is you actually have the power to slow the rate of extinction by what you do in your own garden and backyard, and that’s empowering!
The best thing you can do for the animals and environment is plant flowering plants, shrubs and trees that are native to the area in which you live, according to Dr. Douglas Tallamy, author of Bringing Nature Home, and a professor at University of Delaware. He wrote:
Native plants are the indigenous terrestrial and aquatic species that have evolved and occur naturally in a particular region, ecosystem and habitat. Species native to North America are generally recognized as those occurring on the continent prior to European settlement.
Tallamy lectures all over the country about how specialized relationships between animals and plants are the norm in nature rather than the exception. Of course, native species will differ according to where you live in the U.S. But overall his message is simple: Plants that evolved in concert with local animals provide for their needs better than plants that evolved elsewhere.
“He talks about things like the importance of growing native plants that will attract native caterpillars, because birds need caterpillars to rear their young,” said Dr. Kimberly Stone, a bee researcher at the Connecticut Agricultural Experiment Station who, on Jan.1, 2017, published A Citizen’s Guide to Creating Pollinator Habitat in Connecticut.
Tallamy’s research has shown that alien ornamentals support 29 times less biodiversity than do native ornamentals. He points out that in the U.S. gardeners often plant Kousa dogwood, a species from China that supports no insect herbivores, instead of our native flowering dogwood (Cornus florida) that supports 117 species of moths and butterflies alone.
“In hundreds of thousands of acres we have planted golden raintree from China instead of one of our beautiful oaks and lost the chance to grow 532 species of caterpillars, all of them nutritious bird food,” Tallamy writes.
Cultivars vs native
As a bee researcher, Stone is thrilled that Tallamy has developed a constituency over the last several years, and says that when you combine that with the fact that initiatives to address pollinator decline are widespread and growing in the U.S.—there truly is a movement towards cultivating habitats that foster pollinators.
However, while a growing demand for native plants in ecological landscape sounds fantastic, there is more to the story.
The demand has led to the selection and breeding of native cultivars by the nursery and landscape industry. A cultivar is a human-bred variety of a native plant that has been selected, cross-bred, or hybridized for more “desirable” characteristics.
In fact, cultivars are becoming more readily available for purchase at garden centers than true natives.
The problem is that some of the traits humans find attractive in cultivars when they try to create that jaw-dropping garden that is the envy of their neighbors—such as larger flowers, double flowers, shorter stems, or unique color—can actually make the plant less attractive to pollinators, according to growing research conducted by Annie White, adjunct professor at the University of Vermont and owner of NECTAR Landscape Design, as well as another study, Penn State’s Pollinator Trial, that took place from 2012-2105.
One clear trend in the University of Vermont research was observed across all species; the more manipulated the cultivars became, the less attractive they became to pollinators. Although the research didn’t answer why some pollinators preferred the straight native species, researchers hypothesized the color differences and decreased nectar and pollen production in hybridized cultivars were leading factors.
In Penn State’s experiment, there were 14 direct comparisons and about 50 percent of the time the straight native species was better than the cultivar. For example, Monarda fistulosa, was substantially better than the cultivar, Monarda ‘Claire Grace’. On the other hand the cultivar Symphyotrichum ‘October Skies’ was substantially better than the true native species Symphyotrichum oblongifolium. Researchers concluded it was not possible to generalize that cultivars are always poorer than straight native species when it comes to being attractive to pollinators.
What’s a gardener to do?
Stoner advises gardeners who want to guarantee their plants will fit into their native ecosystem in a natural way and attract pollinators to ask for straight native species as opposed to cultivars.
“Asking for straight species will ensure you have a plants that fit into your local ecosystem that the animals in your area have evolved with. You may have to go to smaller more specialized nurseries in order to find the straight species,” Stoner said. “I know, for example, that in Connecticut there are some really small nurseries focused on straight species of native plants that are native to CT that don’t ship their plants to other places. I assume there are other nurseries like that around the country if you do some investigating.”
Tallamy is forgiving when it comes to why people don’t realize their yards are wildlife preserves that represent the last chance we have for sustaining plants and animals that were once common throughout the country.
“If this is news to you, it’s not your fault,” he writes. “We were taught from childhood that gardens are for beauty; they are a chance to express our artistic talents, to have fun with and relax in. And, whether we like it or not, the way we landscape our properties is taken by our neighbors as a statement of our wealth and social status.
“But no one has taught us that we have forced the plants and animals that evolved in North America to depend more and more on human-dominated landscapes for their continued existence. We have always thought that biodiversity was happy somewhere out there ‘in nature;’ in our local woodlot, or perhaps our state and national parks. We have heard nothing about the rate at which species are disappearing from our neighborhoods, towns, counties and states. Even worse, we have never been taught how vital biodiversity is for our own well-being.”
Nicole Rivard is editor of Friends of Animal’s quarterly magazine Action Line. She brings 18 years of journalism experience to the front lines, protesting and documenting atrocities against animals.