And what isn’t? Designers and pollinators are finding out.
By Carol Becker
Common buttonbush (Cephalanthus occidentalis) is a medium-sized shrub that is appealing in sunny areas of the landscape because of its glossy green leaves; unusual fragrant, round, spiky flowers; and rust-red fall color. It’s especially useful in wet areas and rain gardens where it absorbs excess water and even tolerates standing water. Hummingbirds and butterflies favor the plant for its nectar, and 24 species of birds seek it out for its small, round nuts that persist into winter. This native of the Midwest and East Coast is easily grown and little bothered by pests in the garden. Yet it is not commonly used in built landscapes. Although everything else about this shrub is right, its growth pattern and size are not. The straight species can be quite large at 12 feet high or more, and it has an annoying habit of sending branches in all directions, so it looks willy-nilly rather quickly if it’s not pruned regularly and often.
But here come Sputnik, Sugar Shack, and Fiber Optics, cultivars of buttonbush that represent a tamed C. occidentalis. Cultivars are plants produced by selective breeding or vegetative propagation to achieve better traits for the landscape. Fiber Optics is a species mutation discovered by an inventory employee in the bare-root fields of Bailey Nurseries, says the company’s public relations and communications specialist, Ryan McEnaney. Bailey trialed the plant, a process that takes several years, and brought it to market in 2017. It has a reliably smaller size at five to six feet high and a branching habit that keeps it compact and rounded, while retaining all the desired features of the straight species.
The Fiber Optics buttonbush is what is known as a nativar. The term is not scientific but has value to the industry in helping identify selected, hybridized, or crossbred varieties of native plants. The horticulturist Allan Armitage recalls that he coined the term “nativar” around the time he wrote Armitage’s Garden Perennials, which was published in 2000. Its purpose: to connect the industry to the powerful influence that the native plant movement was having on trends in buying.
The native plant movement, Armitage says, is “one of the very few times when the horticulture industry was swayed by the gardening community.” Usually, new plants developed by breeders influence what gardeners buy, but gardeners had been demanding plants with local or regional provenance. Though the movement was small at first, Armitage recalls, it “was going full steam before breeders even knew what was happening.” He coined the term “nativar” to show customers that the industry was offering what they wanted: garden plants developed from documented native sources, known in the scientific community as genotypes.
“Nativars allow us to retain the ecological benefits of native species while making them adaptable and accessible for a modern landscape,” McEnaney says. “Whether that means a more compact size, cleaner foliage, better color, or a tidier appearance, nativars solve problems that can arise” with the genotype.
The native plant movement is still a strong influence on the market, owing not only to the early adopters who started it but to causes: saving pollinators and growing healthy food. Until the value of native plants was tied to these concepts, the movement was localized, small, and valued primarily for restoration. It has exploded through effective marketing that the average gardener can understand. The value of the term nativar in this context is a huge benefit to growers and garden centers who wanted to connect to the customer seeking a new product.
Nativars have been developed for every type of plant: trees, woody shrubs, forbs, and grasses. Any cultivar that is derived from a locally sourced species plant is a nativar. Some are cultivated from naturally occurring variations that improve the look or performance of the species. Others are crossbred or hybridized to obtain smaller size, stronger stem strength, new or better flower color, a regular growth pattern, better disease resistance, or other qualities.
Of the hundreds of trees native to North America, many have been cultivated for better form or size, and nativar trees are widely in use. The Bailey First Editions series, for example, includes trees such as the Majestic Skies northern pin oak, a nativar of the straight species Quercus ellipsoidalis bred to be straighter and with a more symmetrical form, both traits valued for street and landscape trees. Woody shrubs are also becoming more common as supply chains respond better to demand in the market. They address a need long felt in the landscape industry for shrubs that will be hardy, more pleasing, and easier to grow. There are now several choices of ninebark (Physocarpus opulifolius) to substitute for, say, invasive barberry, and Diervilla lonicera nativars that supplant invasive honeysuckles and won’t sucker aggressively to form thickets in the garden like the species plant. Suckering is a particularly ill-favored trait that nativars often overcome. We can now plant the non-suckering sumac Tiger Eyes (Rhus typhina ‘Bailtiger’), a great alternative to the species plant from Bailey Nurseries, with a chartreuse to golden leaf color and striking form that has the look of a Japanese maple but is much easier to grow.
Nativars of wildflowers and grasses are now widely available from a variety of sources. The grower Midwest Groundcovers provides a typical example of how true natives and nativars reach the market. The company sells a line called Midwest Natives, which it classifies as “common Midwestern native species” grown from seed collected in the Upper Midwest; Natural Garden Natives, true ecotypes from seed collected within 90 miles of the company’s nursery site in St. Charles, Illinois; and American Beauties Native Plants, a limited selection of 20 plants, of which two are true natives and 18 are nativars in the 2019 offering. A look at sales trends at Midwest Groundcovers confirms Armitage’s prediction, says the company’s president, Christa Orum-Keller, ASLA. American Beauties increased in sales by 50 percent from 2017 to 2018.
The value of nativars is beauty, ease of care, “and maintaining ecological integrity,” says McEnaney. He and others in the world of plant marketing can safely make this claim now, with some caution, given recent research by both Doug Tallamy, an entomologist at the University of Delaware, and Annie White, a lecturer at the University of Vermont and the owner of Nectar Landscape Design Studio, LLC. Each has published findings that help answer the question long on the lips of native plant enthusiasts: Do nativars support insect and bird life? The answer, as it turns out, is a qualified yes.
Tallamy conducted field studies of six of the most preferred traits in woody nativars: reduced growth habit to smaller and more regular forms, changes in leaf color from green to red or brown, added leaf variegation, enhanced fruit size, increased disease resistance, and enhanced fall color. As for insect response, it takes years, not seasons, to reach conclusions, and the study of more than one aspect of insect response is necessary for reliable results. With species plants and cultivated natives (nativars, but not so named in his study because the term is not accepted scientifically) planted side by side, Tallamy’s team studied three insect behaviors: what lepidoptera caterpillars do, how and whether hatching bagworms recognize plant differences, and the overall insect impact on the plant during a season.
Any cultivated plant is a genetic variant, so “it depends on what is changed in the genome as to whether it’s going to impact the insects or not,” Tallamy says. “Insects use plants. They look at the plants and they find them palatable or not through leaf chemistry. If the cultivar change does not change leaf chemistry, the insects don’t care. If it does change the leaf’s chemistry in a negative way, the insects do care.”
With that explanation, Tallamy’s short answer derived from research was that the only trait out of the six that consistently deterred insect use was changing green leaves to red or purple or blue. “It makes sense. Everyone wants red leaves, but what this does is remove chlorophyll from the leaf and load it with anthocyanins, which just happen to be feeding deterrents,” Tallamy says.
White, who has a master’s degree in landscape architecture and experience in a perennial breeding nursery, ecological restoration, and design, pursued a PhD precisely because she wanted to study a similar question, but in relation to plant flowering. “The biggest challenge for me was figuring out where to start. I had this question because I’d been working as an ecological landscape designer for six years at that point and kept specifying native plants and…a lot of times contractors were putting in nativars instead of the native species.”
Her 2016 dissertation compared what she termed the “floral rewards” of native plants as compared to cultivated natives (again, not called nativars in scientific research). Over two seasons, she counted pollinators (primarily bees, flies, butterflies, and moths) on 11 matched pairs of species plants and nativars readily available in the nursery trade to determine the impact on insect life of changes in various “floral resources.” Fundamental to her research, White says, is that, “while the natural history of our world’s pollinator species is widely divergent, they all rely on flowers as a food source” and in so doing, they function as pollinators. The most significant floral resource is color, but flower size, shape, and presentation of its reproductive parts will also determine what its pollinators will be. When these qualities are changed to create nativars, pollinators will be affected.
White’s research provides a systematic look at how pollinators react to cultivated varieties of native forbs. “Many insect pollinators prefer to forage on native species over cultivated varieties,” she says, but it’s not always so. “Some native cultivars may be comparable substitutions for native species in pollinator habitat restoration” but the variables are so many that cultivars should still be evaluated individually. For technical reasons deep in the botany and chemistry of flowers, nativars with certain characteristics are typically less desirable to pollinators. These include sterile flowers, double or triple flowers, color that does not attract the pollinator, or an altered plant form that makes reaching the nectar difficult for the insect (as in, it can’t fit in there anymore). Typically, cultivated natives that have been altered in more ways than one both weaken plants and make them unattractive to pollinators. This is seen in Echinacea that has been altered to come in different colors, as well as smaller size and with double flowers. Such cultivars are altered in up to three ways from the species. (See a few of the cultivated natives that passed muster in White’s research in the list of Nativars to Know, below.)
Although the results of these studies are positive in general, it isn’t possible to re-create the ecosystem of the past just by planting species or nativar plants in our gardens, cautions the biologist Gerould Wilhelm, who cowrote the definitive Plants of the Chicago Region. The reason: The ecosystem of the past “was based on aboriginal soils” that contained continually regenerating organic matter, soil fungi, and a full array of insects to interact with the life cycle of plants. In that context, native plants flourished, and nativars too would play their best part. He calls that kind of soil “the sweet interface between heaven and earth where life lives.” But today, soils are both compacted and degraded, and therefore need constant maintenance to re-create the environments that native plants require. In fact, Wilhelm says, “Contrary to the rhetoric, native plants are less suited to survival in our degraded soils than plants that have already been under cultivation.”
In terms of increasing pollination, some nativars are adequate substitutions for species plants in a landscape. But to get the maximum benefit of their native properties, the final step in using nativars is a design challenge, says the plantsman and designer Roy Diblik, the developer of the well-known nativar Panicum virgatum ‘Northwind’ and author of The Know Maintenance Perennial Garden. It requires careful observation “of the changing ethic of garden design we see emerging now,” that is, the development of plant communities in a free-form garden palette maintained by precise practices that aggressively build organic matter into the soil. This approach allows the designer to combine species plants, nativars, and perennials close to each other in patterns that recognize the compatibility of their growth habits. It creates a mix of greater beauty than any one of the plant classes alone, Diblik says. For example, stiff tickseed (Coreopsis palmata), wild quinine (Parthenium integrifolium), and pale purple coneflower (Echinacea pallida) are three true natives with thin, unremarkable stems but interesting showy flower shapes and light colors (yellow, white, lavender) that mix well with the dark stems and the dark purple flower of the nativar Echinacea ‘Fatal Attraction’ and the beautiful texture of Russian sage (Perovskia atriplicifolia), a perennial. Using this technique, the design emerges as plants grow together to create drifts of texture and color.
At the Shedd Aquarium on the shore of Lake Michigan in Chicago, the horticulturist Christine Nye used this approach in 2008 in creating the aquarium’s Migratory Bird Garden. It was the last of 13 different mixed species and nativar gardens at Shedd. The garden was designed by Diblik and built over several inches of crushed rock and only two inches of topsoil, not the 12 that were specified after a major construction project. Knowing that sod would never grow, Nye suggested adding the acre to Shedd’s expanding gardens, situated along the Mississippi Flyway.
After the addition of only two inches of leaf mulch, Diblik planted the garden with 55 woody and herbaceous perennials—natives and nativars. Woody nativars include Bergeson Compact dogwood (Cornus sericea ‘Bergeson Compact’), Prairie Flame shining sumac (Rhus copallinum var. latifolia ‘Morton’), Regent serviceberry (Amelanchier alnifolia ‘Regent’), and Mohawk viburnum (Viburnum x burkwoodii ‘Mohawk’). The herbaceous plantings include the nativars Husker Red beardtongue (Penstemon digitalis ‘Husker Red’), Phantom joe-pye weed (Eupatorium x ‘Phantom’), Wichita Mountains goldenrod (Solidago ‘Wichita Mountains’), Karl Foerster feather reed grass (Calamagrostis x acutiflora ‘Karl Foerster’), and Diblik’s own nativar brand of switchgrass (Panicum virgatum ‘Northwind’), among others.
Maintenance is utterly unlike that for a traditional garden, says the plantsman, Ken Williams, who is solely responsible for maintaining the Shedd Aquarium’s 13 gardens, working one day each week. Starting with fall, no cleanup. Then in spring, whacking weeds and leaving the debris in the garden to decompose. Throughout the summer, using a Dutch hoe to remove ever so carefully only the unwanted plants. “The idea is to allow debris to decompose into organic matter, allow plants to grow together over time, and allow soil to remain undisturbed as much as possible,” he says. “Don’t sweat the small stuff. As the season goes on, stop, look, let volunteer plants come up in empty spots, weed only what doesn’t fit the form of the emerging garden.” He adds: “What you are doing is managing opportunities. Eventually you want the plants to function as a whole” in terms of form, texture, and color. A big part of this technique is about rebuilding the soil.
After 10 years of tending this garden, Nye’s migratory bird sightings “have increased from one mating pair of red-winged blackbirds to hundreds, and expanded to include many other species,” including warblers, thrushes, hawks, cormorants, eastern towhees, Carolina wrens, rose-breasted grosbeaks, kestrels, brown-headed cowbirds, American goldfinches, phoebes, brown thrashers, ruby- and golden-crowned kinglets, brown creepers, and cedar waxwings.
Nativars to Know
Herbaceous and woody nativars were picked as favorites by the author and contributors to this article:
Asclepias tuberosa ‘Hello Yellow’ (Hello Yellow butterfly milkweed)
Developed and named for its bright yellow flowers. Otherwise not significantly different from the species plant and favored for pollinators in research by Annie White. This and many other herbaceous nativars represented here are available from the American Beauties series.
Carex muskingumensis ‘Oehme’ (Oehme palm sedge)
A clumping palm sedge chosen by Christa Orum-Keller, ASLA, with horizontally radiating green leaves variegated with narrow yellow margins. Developed from a sport reportedly discovered in the garden of the landscape architect Wolfgang Oehme.
Cornus sericea ‘Bergeson Compact’ (Bergeson Compact red osier dogwood)
Christine Nye at the Shedd Aquarium favors this nativar dogwood shrub above all others. It has a compact habit, reliable red stem color, and burgundy leaves in fall.
Deschampsia cespitosa ‘Pixie Fountain’ (Pixie Fountain tufted hair grass)
A dwarf tufted hair grass. “Beautiful puffy habit, tight, compact, great show,” says Orum-Keller. Introduced by Jelitto Perennial Seeds of Louisville, Kentucky.
Echinacea purpurea ‘White Swan’ (White Swan coneflower)
Though less hardy than the species plant, this coneflower was the only one of the Echinacea nativars that did well in White’s pollinator studies. Named for its huge white flowers. Introduced by Thompson & Morgan in 1987.
Heuchera americana ‘Dale’s Strain’ (Dale’s Strain American alumroot)
Selected by Orum-Keller as the “perfect ground cover and blending plant that goes with nearly everything.” Marbled leaves with silver blue and red in season, turning coppery orange in fall and winter. Discovered in North Carolina and developed by Dale Hendricks of North Creek Nurseries.
Hypericum kalmianum ‘PIIHYP-I’ (Cobalt-n-Gold hypericum)
Hypericum is beautiful and underrepresented in the landscape, as far as the author is concerned. This woody nativar from Bailey First Editions should boost its popularity. It’s compact, fine with dry soils, and resists deer.
Ilex verticillata ‘Bailfire’ (Wildfire winterberry)
This woody nativar selection from Bailey First Editions, trademarked as Wildfire winterberry, offers larger red berries than the species, says Ryan McEnaney in selecting it. Moisture tolerant, with good form and winter appearance.
Monarda fistulosa ‘Claire Grace’ (Claire Grace wild bergamot)
This bee balm nativar has brighter pink flowers and better drought hardiness and resistance to mildew than the species. Discovered in Tylertown, Mississippi, it is best for central and southern locations. Selected as a pollinator that did well in White’s research.
Panicum virgatum ‘Northwind’ (Northwind switchgrass)
A versatile landscape grass discovered in northern Illinois and developed by Roy Diblik for its strong upright growth habit that makes it very useful in plant combinations. Grows up to 72 inches by fall.
Penstemon digitalis ‘Husker Red’ (Husker Red beardtongue)
Red foliage and a stronger upright stem than the species. Selected by Nye for the Shedd Aquarium Migratory Bird Garden. Did well in pollinator studies by White. Discovered by Dale Lindgren at the University of Nebraska-Lincoln.
Physocarpus opulifolius ‘Donna May’ (Little Devil ninebark) and Physocarpus opulifolius ‘Jefam’ (Amber Jubilee ninebark)
Bailey First Editions developed both of these woody nativars, trademarked as Little Devil and Amber Jubilee. Both are good subs for the invasive barberry with disease resistance and a unique foliage color. As its name suggests, Little Devil is smaller than the species.
Polemonium reptans ‘Stairway to Heaven’ (Stairway to Heaven Jacob’s ladder)
Author favorite. Also selected by Orum-Keller for its striking white, pink, and green variegated leaves and larger blooms than the species. Discovered in a Massachusetts nursery and introduced by the New England Wildflower Society.
Rudbeckia fulgida var. sullivantii ‘Goldsturm’ (Goldsturm black-eyed Susan)
‘Goldsturm’ is more compact and coarse than the species and has a shorter bloom duration. Selected by White as one that attracted pollinators well. Discovered in a nursery in the 1930s.
Veronicastrum virginicum ‘Lavendelturm’ (Lavender Towers Culver’s root)
A lavender-flowered option to the species’ white blooms. Somewhat taller than the species and equally effective in wet areas. Did well in pollinator studies by White.
Shedd Aquarium Migratory Bird Garden
Callitropsis nootkatensis ‘Pendula’ (Weeping Alaska cedar)
Juniperus virginiana ‘Glauca’ (Silver eastern red cedar)
Picea glauca ‘Densata’ (Black Hills spruce)
Aesculus parviflora (Bottlebrush buckeye)
Amelanchier alnifolia ‘Regent’ (Regent serviceberry)
Aronia melanocarpa (Black chokeberry)
Cephalanthus occidentalis (Common buttonbush)
Chionanthus virginicus (White fringe tree)
Cornus sericea ‘Bergeson Compact’ (Bergeson Compact dogwood)
Corylus americana (American hazelnut)
Hamamelis vernalis (Ozark witch hazel)
Hypericum kalmianum (Kalm’s St. Johnswort)
Rhus copallinum var. latifolia ‘Morton’ (Prairie Flame shining sumac)
Viburnum nudum var. cassinoides (Withe rod)
Viburnum prunifolium (Blackhaw)
Viburnum x burkwoodii ‘Mohawk’ (Mohawk viburnum)
Natives, Nativars, and Perennials
Achillea filipendulina ‘Altgold’ (Fernleaf yarrow)
Allium angulosum ‘Summer Beauty’ (Summer Beauty onion)
Allium cernuum (Nodding onion)
Amsonia tabernaemontana var. salicifolia (Eastern bluestar)
Bouteloua curtipendula (Sideoats grama)
Calamintha nepeta ssp. nepeta (Lesser calamint)
Coreopsis palmata (Stiff tickseed)
Coreopsis verticillata ‘Golden Showers’ (Golden Showers tickseed)
Echinacea pallida (Pale purple coneflower)
Echinacea purpurea ‘Alba’ (White coneflower)
Echinacea purpurea ‘Rubinglow’ (Purple coneflower)
Eryngium yuccifolium (Button eryngo)
Eupatorium x ‘Phantom’ (Phantom joe-pye weed)
Kalimeris incisa ‘Blue Star’ (Blue Star Japanese aster)
Liatris aspera (Tall blazing star)
Limonium gerberi (Sea lavender)
Nepeta ‘Early Bird’ (Early Bird catmint)
Nepeta racemosa ‘Walker’s Low’ (Walker’s Low catmint)
Parthenium integrifolium (Wild quinine)
Penstemon digitalis ‘Husker Red’ (Husker Red beardtongue)
Pycnanthemum muticum (Clustered mountain mint)
Pycnanthemum virginianum (Virginia mountain mint)
Rudbeckia fulgida (Orange coneflower)
Ruellia humilis (Fringeleaf wild petunia)
Salvia nemorosa ‘East Friesland’ (East Friesland meadow sage)
Salvia x sylvestris ‘Blue Hill’ (Blue Hill meadow sage)
Salvia x sylvestris ‘Rhapsody in Blue’ (Rhapsody in Blue wood sage)
Silphium terebinthinaceum (Prairie rosinweed)
Solidago ‘Wichita Mountains’ (Wichita Mountains goldenrod)
Stachys officinalis ‘Hummelo’ (Hummelo betony)
Calamagrostis x acutiflora ‘Karl Foerster’ (Karl Foerster feather reed grass)
Panicum virgatum ‘Northwind’ (Northwind switchgrass)
Panicum virgatum ‘Rotstrahlbusch’ (Red switchgrass)
Schizachyrium scoparium (Little bluestem)
Sesleria autumnalis (Autumn moor grass)
Sesleria heufleriana (Blue-green moor grass)
Sporobolus heterolepis (Prairie dropseed)
Carex flacca (Heath sedge)
Carex pensylvanica (Pennsylvania sedge)
Carol E. Becker is a Chicago-based writer and landscape designer specializing in the use of natives, nativars, and perennials in sustainable landscapes.