Just what are keystone plants? Well, keystone plants are plants which a habitat or ecosystem is mostly dependent on to thrive. By removing these species, you may collapse an ecosystem or limit its ability to keep biodiversity in place. If add keystone plants back into the landscape, you can increase biodiversity within region. We gardeners have an opportunity to preserve habitats and increase biodiversity among our unnatural landscapes within the overall landscape.
What types of wildlife do keystone plants affect? All kinds, from fungi and micro-organisms in the soil to the largest mammal predators and birds. There are also keystone animals, usually predators and grazing mammals which can change the diversity of a region by their presence or absence. For more information on an overall project and keystone species in general, I suggest the book Wilding by Isabella Tree or the Knepp Wilding Project on YouTube.
Keystone Plants in Our Region
Here in the Central Great Plains Region, we have a unique crossover of species. I defined our region as a rough square 150 miles by 150 miles, from Marysville, KS to Jamesport, MO and from Blair, NE to Emporia, KS. We are unique for the area because we have to main ecoregions crossing together: the Great Plains and the Eastern Temperate Forests. So we catch Keystone plants from both ecoregions.
Keystone plants are mostly trees and woody shrubs, but can also include perennials whose absence would be marked by the loss of specialist bees or other pollinators. For example, we have seen a dramatic decline Monarch butterflies within our region over the last 30 years, after increased use of herbicides in the agriculture industry of our regions which affected milkweed populations. Monarchs are a specialist species, requiring milkweeds to reproduce. If you remove the milkweeds, you remove the Monarchs.
What Happens When Keystone Plants are Removed?
What happens when you take out a keystone species is that there is a rippling effect on the entire ecosystem. The bur oak for example. If it was removed either by disease or destruction completely, it would wreck the habitats of many lives. A large number of insects, arachnids, and others feed on the tree, which are in turn consumed by birds, small mammals, and reptiles. These consumers are then eaten by larger birds (raptors), hunting mammals, snakes, and others. When the bodies of these animals and the tree parts die and decay, they are fed upon by other animals, insects, fungi, and micro-organisms.
Do you love songbirds? I love chickadees, tufted titmice, and meadowlarks. The black-capped chickadee, a year-round resident of the Central Great Plains, uses caterpillars as the food source for raising its young. For one clutch, 3 to 5 fledglings, a pair of chickadees may use 9,000 to 15,000 caterpillars in a 16 to 18 day period. That is a LOT of caterpillars. And without keystone plants, those caterpillars would not be available.
Kinds of Keystone Plants
While trees are the most important keystone plants in our region, there are certainly others (like the aforementioned milkweed). I will go over some of the more important species and how you can incorporate them into your landscape. There are 3 categories: trees, shrubs, and flowering perennials. Though I daresay that if you removed unmowed native grasses from an area, you would also lose all your grass skipper butterflies.
Trees
There a 7 Genera of trees which concern us in the Central Great Plains. Of these, Quercus, is the most important and provides the most for all kinds of wildlife. But there are others which play an important role as well. As we dive into each tree, I will give the best example for wildlife, and some alternatives which may be better for smaller or more constricted home landscapes as well.
Oak – Quercus species
The oak is often considered the mightiest tree in the forest. Not always for size, but for its importance within. And oaks not only grow in forests, but throughout the prairies of Great Plains region. In the Eastern Temperate Forests, the white oak, Quercus alba, is seen as the most important keystone plant. In the Great Plains, it is the bur oak, Quercus macrocarpa. Between these two oaks, some 400-500 species of moths and butterflies use it as a host for their caterpillars. That in turn feeds songbirds and rodents, and so on down the food chain.
In the photo below are just a few of the many moths and butterflies which feed on oaks in our region. I have to look more for the adults of these than the caterpillars, because birds eat so many caterpillars before I see them.
Besides moths and butterflies there are other feeders. Gall wasps, tree crickets, leafhoppers, treehoppers, aphids, plant bugs, katydids, beetles, and more feed on the leaves, stems, bark, and roots of oaks. And another insect which feeds heavily on oaks are sawflies, whose larvae resemble caterpillars.
Both of the above mentioned trees are large, long-lived trees. They can be planted into larger landscapes, but may not be an option inside towns or in more constricted lots. If you are wanting to plant more oaks into your area, and are limited in space, try some of the following:
- Dwarf chinkapin oak, Q. prinoides – grows 15 to 25 feet tall and wide.
- Swamp white oak, Q. bicolor – grows 50 to 60 feet tall and wide.
- Blackjack oak, Q. marilandica – grows 50 feet tall by 40 feet wide.
Willows – Salix species
The National Wildlife Federation has willows listed as shrubs as keystone plants, but we have them more as small to medium trees. Particularly, the black willow (S. nigra), is a medium sized tree in our area. I have documented some specimens growing around 40 feet tall and 30 feet wide, putting them into the tree category. Among the willows, they support 450 plus species of moths and butterflies, plus sawflies and beetles. And there are at least 6 other species which will grow well for us.
- Peachleaf willow – S. amygdaloides
- Missouri River willow – S. eriocephala
- Starved willow – S. famelica
- Interior sandbar willow – S. interior
- Prairie willow – S. humilis
Now, willows are not commonly planted in landscapes because they are usually short-lived and drop a lot of branches. But they can be incorporated into spots where there are boggy or wet areas, or added along ponds or streams. I think homeowners who are trying to add biodiversity in the landscape could add smaller willows such as Prairie willow or dwarf prairie willow (S. humilis tristis) into the a meadow garden area or near the property edges.
Cherries/Plums – Prunus species
The cherries are often overlooked as landscape plants because they are often not trees, but overgrown shrubs. And most are thicket-forming, meaning they sucker and grow over a large area. However, if you live in the country with some room. having suckering plants along the property edge can be a blessing. Together, the cherries and plums produce food for 200-350 species of moths and butterflies, and other arthropods as well. Some of our favorite butterflies prefer to use our native cherries over other trees.
The main tree in our region is the black cherry (Prunus serotina) which is highly valued for its wood and the flavoring from its fruit. Other species include the following:
- American plum, P. americana – is a large thicket former, growing 15 to 20 feet tall.
- Chokecherry, P. viginiana – can be grown as a small tree (15 to 25 feet tall by 20 feet wide) or as a thicket forming shrub.
- Sandhill plum, P. angustifolia – is a smaller shrub, growing 4 to 6 feet tall and wide.
Cherries and plums in our region are also host to a wide range of fungal infections, which may make them more unsightly in the landscape. Which could lead them to be less desired overall. But you can always plant them on the outskirts of a property, or hide them among other plantings. I would not recommend yearly fungicides on these plants as it will likely affect pollinator species.
Eastern Cottonwood – Populus deltoides
The eastern cottonwood is one of the most majestic of our native trees, and also one of the most disliked in communities. This is because the cottonwood has brittle branches and often loses many branches in storms. Also, the “cotton” of the tree comes from the seed production of the female trees. This cotton gets stuck in ac units, window screens, on windshields, and much more. But the cottonwood is home to 250 species of moths and butterflies, making it vital for our ecosystem.
Unfortunately, there are no smaller species or cultivars to choose from, though there are some selections of the male trees which do not produce any seeds or cotton. Look for ‘Souixland’ or ‘Robusta’. If you are wanting to plant species cottonwoods on your property, I suggest locating them away from homes, at least 100 feet away to protect from both the branches and surface roots.
Maples – Acer species
Many people do not think of maples as being native to Kansas and Nebraska. Yet we have 4 species which are native and somewhat common in our area. Between them, they support up to 250 species of moths and butterflies, along with other arthropods. A lot of the maples which are in our cities are hybrids or nonnative maples like the Japanese maple or Shantung maple. But there are plenty of sugar maple (A. saccharum) and silver maple (A. saccharinum) as well. The two other native species which play a part in our region is the black maple (A. nigrum) and the boxelder maple (A. negundo). Of these, the boxelder is little used in landscapes, but can be found in wetter areas around lakes, woods, and marshes.
There are many cultivars of our native sugar maples which can be used instead of a seedling. They have been selected for a variety of reasons including size, fall color, and hardiness. I like to use any of the following cultivars for our region:
- Oregon Trail
- Fall Fiesta
- Flashfire
- Legacy
- Caddo
- John Pair
Hickory – Carya species
Hickories are our second to-last category of trees to plant to support wildlife. They are one of my favorite groups of trees because they all have interesting characteristics. And I find almost as many galls on hickory as I do on oaks. Surprisingly, the hickories are not considered keystone plants in the Eastern Temperate Forests, but rather in the Great Plains region. I am not sure why this is because they support 153 species of moths and butterflies.
The real problem with hickories is that they are hard to grow in the nursery and so many people have never seen them outside of the woods. Of all species, the pecan (C. illinoiensis) is the most widely planted and known, because it has edible nuts. But both the Shagbark (C. ovata) and kingnut (C. laciniosa) also have edible nuts, but in harder shells. Other hickories that should be considered are the bitternut (C. cordiformis), pignut (C. glabra), and mockernut (C. tomentosa). All will grow well in our area and can often be found hybridizing with each other.
Eastern White Pine – Pinus strobus
While the eastern white pine is not actually native in our region, it is widely grown and planted in windbreaks, cemeteries, and cities. And because it is native in the Eastern Temperate Forests, we get some of the 200 insects that pines support in our region. Among the pines, there are number of cultivars in various forms, from weeping to columnar to shrub like. So it can be easy to add any number of pines to the landscape.
Just be sure to add native pine species to promote native insects and wildlife biodiversity. Any of the following list of species will grow in our region:
- Eastern white pine – P. strobus
- Limber pine – P. flexilis
- Jack pine – P. banksiana
- Ponderosa pine – P. ponderosa
- Southwestern white pine – P. strobiformis
- Red pine – P. resinosa
- Virginia pine – P. virginiana
Shrubs as Keystone Plants
The National Wildlife Federation’s list of keystone plants in the shrub category is almost nonexistent for either the Great Plains or the Eastern Temperate Forests. There are the willows, which I mentioned in the tree category. Otherwise we have the blueberries, none of which grow in the Central Great Plains, as natives. But there are 5 species which are left off the list and are native to our region.
American hazelnut – Corylus americana
Why this was left off the list I do not know. The American hazelnut supports 131 species of moths and butterflies according to Doug Tallamy in Bringing Nature Home. That is a significant number to me. Maybe there is too much overlapping of species between it and oaks or some other of the keystone plants. Anyways, I am including it here. The hazelnut is a large shrub, growing 15 feet tall and wide, sometimes wider as it forms thickets. There are several cultivars available, geared at nut production, because the nuts are edible and quite sweet.
Roughleaf Dogwood – Cornus drummondii
Another shrub that is widespread in the Central Great Plains is the roughleaf dogwood. Counting up, there are at least 65 species of moths and butterflies being supported by the dogwood. And there may be more, because a great number of moths we have no host plant data for. The roughleaf dogwood is often not even considered by landowners or gardeners because it grows in a thicket, fills into ditches and low areas, and has little or no ornamental value. The stems turn reddish in later winter, and there are lovely white blooms in June, but it is otherwise unnoteworthy.
Brambles – Rubus species
There are more species of brambles (blackberries, raspberries, and dewberries) in Kansas than in any other state. Because of this, there are a number of moths and butterflies which utilize these plants as hosts. Some 125 plus do so. Now, a lot of these species are not garden worthy plants, mainly because of their thorniness. But you can add them into a meadow garden or grow them as a thicket on the boundary of a property, to keep trespassers at bay. Following are some of the more common species:
- Garden dewberry – R. aboriginum
- Common blackberry – R. allegheniensis
- Northern dewberry – R. flagellaris
- Prairie dewberry – R. hancinianus
- Black raspberry – R. occidentalis
Roses – Rosa species
Despite the common problems with nonnative roses, there are actually 5 native roses in the Central Great Plains Region. And they host 75 species of moths and butterflies, plus some weevils and beetles, all of which are food sources down the line. Native rose species often do not get the credit they deserve for growing in tough environments. Some, like the Arkansas rose (Rosa arkansana) grow mainly in dry soils, along roadsides in in tough prairies. I think one of the problems is that gardeners see them as a potential host for diseases such as black spot, rose rosette, and others.
Rose species which should be considered for keystone plants in the garden or on the property edges include:
- Arkansas rose – R. arkansana
- Western wild rose – R. woodsii
- Climbing rose – R. setigera
- Carolina rose – R. carolina
- Prairie rose – R. blanda
Serviceberry – Amelanchier species
The serviceberry is an often over-looked tree or large shrub because it blends into the landscape until fall. I have come across common serviceberry (Amelanchier arborea) in 3 counties of Northeast Kansas so far, both in spring and fall. They seem to grow near streams in the woods, but up on the ridgeline away from the water, not with their roots in the stream. The serviceberry hosts around 100 species of moths and butterflies, but also has edible fruits resembling blueberries in size, texture, and taste. This makes them valuable for a wider variety of birds, including those which eat caterpillars and those which eat fruits (thrushes, woodpeckers). There are several other species which can grow in our area, as well as a number of cultivars.
Flowering Perennials
The flowering perennials as keystone plants are important not only for caterpillars, but also for a number of specialist bees which rely solely on certain plant species for nectar and pollen. That is why it is important to plant from all 3 categories of keystone plants, not just 1 or 2. This will insure that you get the best biodiversity available for your region.
Goldenrods – Solidago species
There about 12 species of goldenrods in the Central Great Plains, and 9 of them are commonly found through our area. Most people see goldenrods only when they are blooming, which is primarily from August to October, at about the same time as ragweed. But goldenrod is insect pollinated while ragweed is wind pollinated. The goldenrods are there though, hiding among other blooming plants and playing host to around 100 species of moths and butterflies. Also, in the Great Plains ecoregion, there are 56 species of bee specialists relying on them.
Goldenrods can be incorporated easily into a variety of garden styles and settings, from meadows to woodlands. There are even some shade loving species. And when fall comes the landscape erupts with a dense haze of golden blooms, buzzing with bees, wasps, moths, butterflies, and more.
- Tall goldenrod – S. altissima grows almost 9 feet tall in clumps.
- Woodland or zigzag goldenrod – S. flexicaulis grows 3 feet tall and is the best variety for shade.
- Giant goldenrod – S. gigantea grows about 6 feet tall in large, 3-5 feet wide clumps, and prefers ditches or moist areas.
- Missouri goldenrod – S. missouriensis is one of the most widespread species, growing 1 to 2 feet tall.
- Gray goldenrod – S. nemoralis likes dry areas and grows around 1 to 2 feet tall.
- Downy goldenrod – S. petiolaris grows up to 5 feet tall in woodland glades or edges and prefers dry, rocky soils.
- Rigid goldenrod – S. rigida can grow 3 to 6 feet tall depending on the amount of moisture it recieves.
- Showy goldenrod – S. speciosa is a clump forming species, growing up to 3 feet tall.
- Elm-leafed goldenrod – S. ulmifolia is another part shade lover which grows 3 to 4 feet tall.
Asters – Symphyotrichum species
Asters are another late blooming perennial which often goes unnoticed in the landscape. Until it blooms. Then the asters are often more noticed than anything else and lots of gardeners look to add them to the garden. In the Great Plains, asters provide nectar and pollen to 43 specialist bees and provide food material for 100 moths and butterflies. And they attract a lot more pollinators than just bees.
There are 21 species commonly found in the Central Great Plains of aster, and 5 which are good for gardens and landscapes. Asters are important late summer to fall bloomers which fill gaps in blooms from other perennials which dry up or stop blooming at the same time. The following species and cultivars can be considered for the home landscape.
- Drummond’s aster – S. drummondii grows best in woodland glades and along the edges of meadows, in part shade. It grows 1 to 3 feet tall and 12 foot wide with pale blue flowers.
- Heath aster ‘Snow Flurry’ – S. ericoides grows 1 to 2 feet tall and spreads via rhizomes making it an ideal groundcover for dry, sunny areas.
- Calico aster ‘Lady in Black’ – S. lateriflorum grows 2 to 4 feet tall and 1 to 3 feet wide with pinkish-white flowers above dark green stems and leaves, in full to part sun.
- New England Aster – S. novae-angliae prefers wet to moderately moist soils along ponds and in ditches. It grows 3 to 8 feet tall and can come in a variety of flower colors and cultivars.
- Aromatic aster – S. oblongifolium grows 2 to 4 feet tall and 3 to 5 feet wide. There are several cultivars available, and the flowers are dark purple. They prfer full sun in dry to arid locations.
Sunflowers – Helianthus species
Most gardeners never think about the many perennial species of sunflowers, only the brightly colored and large blooms of the annual sunflower. There are 13 species native to the Central Great Plains region. Of these, only 4-5 should be included in landscapes, mainly in meadows or out of the way areas. Perennial sunflowers play host to 58 species of moths and butterflies and support 89 specialist bees across the Great Plains. Most sunflowers reseed easily and spread via rhizomes into large clumps. Sometimes those clumps can be acres in size.
- Maximillian sunflower – H. maximilliani grows 4 to 6 feet tall and can spread vigorously if not kept in check. Plant it in an existing meadow garden where sod grasses have already established.
- Ashy sunflower – H. mollis grows 3 to 5 feet tall and spreads widely just like others. It has an ash-gray cast to the leaves, hence its name.
- Willowleaf sunflower – H. salicifolius grows 4 to 12 feet tall and can form huge clumps, up to 1/4 and acre in size. But there are several cultivars which can be grown in a garden setting such as ‘First Light’ and ‘Autumn Gold’.
- Tuberous sunflower – H. tuberosus is also known as Jerusalem artichoke and has edible tubers. It grows 5 to 10 feet tall and forms large clumps.
Gumweed – Grindelia species
While these uncommonly known perennials are not big for moth and butterfly caterpillars (just 7), they do support some 68 specialist bees. For that reason alone they are considered keystone plants within the Central Great Plains. There are several species, but just 2 of them are in our region. Curlycup gumweed, G. squarrosa is a dry loving species widespread across Kansas and Nebraska. But Lanceleaf gumweed, G. lanceolata is more common in Missouri and Southeast Kansas. I have lanceleaf growing in my garden and it makes a great cut flower as well as an untidy perennial in the meadow garden.
Companions for Keystone Plants
As with any plantings, you cannot just plant the keystone plants, but need to make sure you have companions which complement them. There are many more species of plants not included on this list which are relied on by individual species, maybe just a few each. But without those plants, their specialist moths, butterflies, bees, or other might disappear from the landscape. I recommend a 75% or greater amount of native plants in your landscape, divided between trees, shrubs, perennials, and grasses for the best group of biodiversity.
Try to add plants from the following list when planning gardens of any type in the Central Great Plains. I have broken them down into 3 categories: sun/dry, shady, sun/wet. But many can be interchanged into each area.
Sun/Dry Keystone Plant Companions
- Wavy-leaf thistle – Cirsium undulatum
- Blanketflower – Gaillardia species
- Black Sampson coneflower – Echinacea angustifolia
- Mexican hat – Ratibida columnifera
- Purple prairie clover – Dalea purpurea
- Western ironweed – Vernonia baldwinii
- False sunflower – Heliopsis helianthoides
- Sneezeweed – Helenium autumnale
- Black-eyed Susan – Rudbeckia hirta
- Rosinweed – Silphium integrifolium
- Hairy ruellia – Ruellia humilis
- Butterfly milkweed – Asclepias tuberosus
- Great Plains yucca – Yucca glauca
- Field pussytoes – Antennaria neglecta
- Leadplant – Amorpha canescens
- Wild indigo – Baptisia species
- Native grasses/sedges
Sun/Wet Keystone Plant Companions
- Buttonbush – Cephalanthus occidentalis
- Swamp dogwood – Cornus amomum
- Elderberry – Sambucus canadensis
- Rattlesnake master – Eryngium yuccafolium
- Golden Alexanders – Zizia aurea
- Hemp dogbane – Apocynum cannabinum
- Swamp milkweed – Asclepias incarnata
- Culver’s Root – Veronicastrum virginicum
- Great Blue lobelia – Lobelia silphilitica
- Torrey’s Rush – Juncus torreyi
- Other rushes/sedges/bulrushes
Shady Companions for Keystone Plants
- Spicebush – Lindera benzoin
- Prickly-ash – Zanthoxylum americanum
- Blackhaw – Viburnum prunifolium
- Hackberry – Celtis occidentalis
- Redbud – Cercis canadensis
- Pawpaw – Asimina triloba
- Purple milkweed – Asclepias purpurea
- Wild ginger – Asarum canadense
- Virginia waterleaf – Hydrophyllum virginianum
- Obedient plant – Physostegia virginiana
- Bloodroot – Sanguinaria canadensis
- Red columbine – Aquilegia canadensis
- Sedges/grasses
Conclusion
Using keystone plants in the landscape can not only increase biodiversity as a whole, but can also help protect species which may be threatened or potentially on the endangered species list. By creating a more diverse landscape individually, we can help the whole region or regions to become better. It it my hope that we can take species such as the Monarch butterfly and various bumblebees off the list in the next few decades. But we need to add back in keystone plants which provide for the ecosystem as a whole and not a single unit.
Happy planting!
