- February 15, 2018
Many of us are wildlife gardeners. We take pride in the sometimes arduous effort of seeking out native plants to add to our habitat-rich gardens. We do this because we believe in the power of biodiversity because we want to feed the birds, bees, butterflies, and billions of other lives that we share our yards and communities with. The effort can be herculean, the payoff noble.
When searching specifically for native plants to add to your gardens, it is helpful to be aware of the growing use of nativars, or cultivars derived from native plants. What are they? Why do we use them? What is their ecological impact? And, what should consumers take into consideration before choosing nativars, especially for those of us who are wildlife gardeners?
On your next visit to your local nursery, try asking the staff to show you their nativars. You may be stared at with questioning eyes, or you may be shuffled to a corner where you’ll see an array of somewhat familiar native plants. Something, however, may be different about these nativars since they are native plants that have been selected from the wild OR hybridized to genetically differentiate them from their native wild-type.
There is a lot we don’t know about the impact of nativar use in our landscapes, as the research is new, limited, and cultivar-variety specific. We have explored what information is available and have compiled insights and suggestions in this article. If all this horticulture language feels confusing, you are not alone. We’ve created the box below to use as a reference. Click on the Nativar Glossary PDF under the image if it is hard to read.
Use of nativars is growing.open_in_new In fact, the vast majority of native plants available in the nursery industry are native cultivars.open_in_new Some are clones of a particularly delightful specimen found in the wild. These plants, however, only represent a fraction of the genetic diversity found in wild populations. Some cultivars may also be hybrids of non-native species‒crossed to enhance a favorable characteristic, like brighter color. While many plants are cultivated to encourage an aesthetic quality that is more desirable to landscape designers and horticulturists, some are created to build resistance to diseases, pests, and changing weather.
Nativars are sometimes found as chance seedlings at breeding nurseries when plants cross-pollinate and reproduce on their own, but the plants you typically come across for sale are far more likely to have been intentionally bred by horticulturalists to enhance a desirable trait.open_in_new Frequent favorable characteristics cultivated in nativars include, but are not limited to; size of flowers, height of plant, color (flower, leaves, stems etc.), growing habitat, disease resistance, and fruit/nut size.
Some wildlife gardeners are asking themselves, If I want to create habitat to support wildlife, but I am using nativars, am I still providing the same ecological function in my yard and community? The answer to this, based on the research available is, it depends.
How to spot a cultivar
It is easy to spot a cultivar. As with the cultivar plant tags in the image above, they usually have plain language names associated with them that describe what is special about this particular cultivar. The breeders who create cultivars usually name them in order to keep track of varieties and help with marketing the plant.
Recent research by Doug Tallamy and Emily Baisden at the University of Delaware explored the interaction between insects and woody shrubs and trees.open_in_new The species they studied included: Red Maple (Acer rubrum), Sweetgum (Liquidambar stryaciflua), American Elm (Ulmus americana), Redcedar (Juniperus virginana), Winterberry (Ilex verticillata), Red Osier Dogwood (Cornus sericea), Highbush Blueberry (Vaccinum corymbosum), and Arrowwood Viburnum (Viburnum dentatum). They found that because all these plants can provide different ecological services, the impact of a nativar vs. a wild-type was case by case.
The nativars investigated had been changed for six traits‒leaf color, variegation, fall color, habit, disease resistance, and fruit size. The conclusion of the research was that the usefulness of the nativar in supporting insect populations‒and thus entire food webs‒was nativar dependent. Because nativars are created for many flowering plants, vines, shrubs, and trees, it may be critical to investigate the specific impacts of each and every cultivar in order to really understand impacts.
One consistent result was that all nativars whose leaves were changed to red, blue, or purple, had a three to five-fold reduction in insect foraging.open_in_new (pictured Red Feathered Viburnum Dentatum ‘JN Select’). One recommendation we can then make is to avoid woody nativars that change the leaf color away from green to other colors. The theory on this is that pigments in leaves are caused by secondary metabolites that can be distasteful to insects. These metabolites, then, can act as a defense mechanism for the plant by discouraging feeding.open_in_new Plants with changed leaf color may be less appetizing and provide a decreased food value to insects.open_in_new
Disease resistance, changed growth habit, larger fruit, and leaf variegation had inconsistent results on insect feeding behavior.open_in_new Sometimes the native wild-type was preferred, sometimes the nativar was preferred, and sometimes there was no measurable preference.open_in_new Thus when it comes to the other characteristics that were measured in this study we simply don’t have enough information to make recommendations‒except that going with the native wild-type is a safe bet if you are seeking to maximize the ecological function of your plants.
It is also important to keep in mind that the more specialized an insect, the more it may be influenced by genetic changes caused by breeding natives with cultivars.open_in_new Perhaps, as research develops, there will be more studies focused on insects that are species-specific, such as the Zebra Swallowtail Butterfly (Eurytides marcellus), pictured, that is host-dependent on Pawpaw (Asimina Triloba).
Nativar flowering plants are also being studied. Annie White, from the University of Vermont, focused on this topic in her dissertation entitled From Nursery to Nature: Evaluating Native Herbaceous Flowering Plants Versus Native Cultivars for Pollinator Habitat Restoration. She studied pollinator visitation on 12 native wild-type herbaceous plant species and 14 native cultivars over a two-year period.open_in_new A brief summary of some of her findings can be read on her blog.
Similar to Tallamy and Baisden, Annie White found that the results often varied by species and nativar variety. In general, she found insects visited native wild-types frequently and were generally preferred even when a cultivar was offered.open_in_new She also notes that frequency of visitation may be insect-dependent.
She found flies were more generalists in their visitations, where bees (both native and honeybee), and moths and butterflies, consistently had similar and more specific preferences. Her research recognizes that native wild vs. native cultivar studies need to be conducted to better understand how different cultivar species may or may not be an equal replacement for their native type. This is critically important for habitat restoration projects where large numbers of plants (sometimes nativars) are used as native species.
White’s dissertation is fascinating. For plant lovers, we encourage you to explore it to learn more details about her findings. Below we’ve chosen a few highlights to share. White found that open-pollinated cultivars, such as Asclepias tuberosa ‘Hello Yellow’ (pictured left) and Monarda fistulosa ‘Claire Grace’ (pictured right), attracted and supported just as many pollinators as the native wild-types Butterfly Milkweed (Asclepias tuberosa) and Bee Balm (Monarda fistulosa).open_in_new
Sometimes the nativar attracted even more pollinators such as Veronicastrum virginicum ‘Lavendelturm’ (pictured), commonly known as culver’s root. These nativars have been bred for longer bloom times and also happen to have higher nectar content. This would suggest that these qualities in a native cultivar may be beneficial in gardens seeking to maximize their ecological function for pollinators.
White also found cultivars that were less attractive to pollinators. Achillea millefolium ‘Strawberry Seduction’ (a similar variety pictured), commonly referred to as yarrow, and Symphyotrichum novae-angliae ‘Alma Poetschke’ (a variety of New England Aster) attracted fewer of all types of pollinators.open_in_new
For those concerned about hummingbird health, White found decreased amounts of nectar and sugar available in the cultivar varieties Lobelia x speciosa, hybrids of the native cardinal flower (Lobelia cardinalis). These cultivars may look pretty and attract hummingbirds with the same bright tubular red flowers of their wild-type, but they deliver 20% less nectar.open_in_new We recommend nativars such as these be avoided as insufficient replacements for their wild-type.
A recurring pattern in White’s research was that when nativars varied significantly in color, size, or shape from their wild-type, they provided less ecological service to pollinators. Using such plants, like Echinacea ‘Mac’n’Cheese’ variety (pictured left) which has orange/yellow petals, unique from the wild-type purple coneflower Echinacea purpurea (pictured right), may result in offering pollinator habitat that is less valuable to wildlife.
Similar research on flowering natives vs. nativars was conducted by Deborah Delaney’s graduate student, Keith Nevison, at the University of Delaware. He measured the sucrose levels and documented the frequency of visitations of insects for six native wild-type and 10 cultivars of Phlox .open_in_new One finding was cultivars Phlox ‘Jeana’ (pictured) and ‘Lavelle’ were far more attractive to pollinators than the straight species Phlox paniculata.open_in_new This is presumed to be due to the ease with which the insects were able to get at the nectar in the narrow-shaped flowers. Both cultivars also had high nectar volume and sucrose content, making them ecologically beneficial to feeding pollinators.
Where do I find Native Plants?
Habitat Network tries to make this easier by connecting you to our Local Resources Tool in our Explore Tab. Type in your zip code and scroll down to the section entitled Native Plant Nurseries Near You. Local native nurseries are your best bet at locating native wild-type plants. You can also try to connect to other wildlife gardeners around you and share seeds or rootstocks of native plants.
In this particular research, it would seem that certain cultivars had some beneficial ecological function compared to the wild-type of Phlox. Keith Nevison suggests that certain nativars may, potentially, act as gateway plants that encourage landscapers who want to maintain ornamental standards but are open to experimenting with native plants in their designs.open_in_new Nevison, however, like White, cautions that nativars need to be considered on a case-by-case basis.
Another word of caution on cultivars (native or not) that can be overlooked–they lack genetic variation.open_in_new Cultivars are often made using cloning techniques. This means that your gorgeous ornamental cultivar Souvenir de la Malmaison rose (pictured) may be genetically identical to the one down the road or thousands of miles away. Cultivars generally are more predictable, but they can present a vulnerability if a particular disease or pest becomes problematic. Without genetic diversity, there is less built-in resilience in our planted landscapes.
Cultivars may help to reestablish plants like the American Elm (Ulmus americana), pictured left, or American Chestnut (Castanea dentata), pictured right, that were nearly wiped out by Dutch Elm Disease and Chestnut Blight. Preliminary results indicate that the Ulmus americana ‘Princeton’ Elm, which is resistant to Dutch Elm Disease, is no less attractive to insects.open_in_new This could be a hopeful sign for the work being done on the cultivated back-crossed American Chestnuts (Castanea dentata).open_in_new If we can use the power of plant breeding to reintroduce lost or struggling species of native plants that can provide the same or similar ecological function to their wild-type, we may just have a winning role for nativars in the wildlife garden.
Why does all this matter? Why focus on whether cultivars, nativars, or native wild-types have different roles to play in our ecosystems? The simple answer is because as habitat continues to shrink due to growing human-dominated (and manipulated) landscapes we need to be mindful of the ecological function of the plants we are planting if we hope to sustain biodiversity. We want to know if the habitat we are working to create using nativars is going to provide the same valuable resources as gardens filled with native wild-type plants. Creating less functional garden ecosystems could put thousands, perhaps millions, of wild‘lives’ at risk—from the smallest insects to the largest mammals.
When in doubt, always buy wild-type native plants and use this summary when considering the use of nativars for your landscape.
- Proceed cautiously with using nativars if you are seeking to maximize your native habitat.
- Feel confident that wild-type native plants provide valuable ecological function in your garden.
- Experiment with woody nativars such as Princeton Elm (Ulmus americana ‘Princeton’) and back-crossed American Chestnuts (Castanea dentata)
- Avoid woody nativars that change the leaf color of the plant.
- Consider trying open-pollinated flowering nativars that are similar in color and shape to their native wild-type, only IF you are unable to locate the wild-type.
- Some flowering open-pollinated nativars to consider are: Phlox ‘Jeana’ and ‘Lavelle’, Veronicastrum virginicum ‘Lavendelturm’, Asclepias tuberosa ‘Hello Yellow’ and Monarda fistulosa ‘Claire Grace’
- Do be cautious and ask your local nursery, “Is this a native wild-type or a nativar?”
- Expect some nativars to not support as diverse of an insect population–both insect herbivores and pollinators.
- Support nurseries that carry wild, open-pollinated natives.
- Reach out to wildlife gardeners around you to try to find sources of native wild-type seeds or plants.
For another perspective on the use of nativars in wildlife gardens, explore this article by WildOnes.