by Elaine Mills, Extension Master Gardener
Photos by Elaine Mills, unless otherwise credited
Keystone plants are genera of native plants that play an especially large role in assuring the survival of other species in the ecosystem. Most importantly, they serve as “host plants” with their foliage providing nourishment for the larval stage of our moths and butterflies. These caterpillars, in turn, are critical components in the food web, transferring plant energy to other animals. The majority of birds, for example, rely on easily digestible caterpillars for nourishing their young. Certain keystone species also support the 25 to 30 percent of our native pollen specialist bees that rely on the pollen from a limited number of specific plants to provision their nests. Additionally, keystone plants may offer floral resources to other pollinators, nuts and seeds to birds and mammals, and cover and nesting sites to a variety of wildlife.
Entomologist Douglas Tallamy provided an initial list of keystone plants (21 genera of woody plants and 21 genera of herbaceous plants) in the 2009 edition of his book Bringing Nature Home. In 2014, Wild Ones, a national group that advocates for the use of native plants, published a chart of woody plants that lists over 60 additional genera of keystone trees, shrubs, and vines to consider for our gardens. In November 2025, Tallamy and Kimberley Shropshire released a complete, literature-based list of all moth and butterfly species in the United States and Canada, along with the plants on which their caterpillars have been documented to feed. Once analyzed, the data, which are presently in a raw format, will certainly provide adjusted numbers for caterpillars supported by each plant genus.
Image use granted by Timber Press
A variety of tools, such as regional guides and state plant atlases, can help gardeners refine the list of locally appropriate species for their home landscapes. (See resources listed below and view the recording of the presentation Keystone Plants for the Home Landscape for a more detailed discussion on selecting plants native to the Mid-Atlantic.)
Keystone Trees
Quercus is the plant genus most supportive of Lepidoptera, with oak trees serving as larval hosts to well over 500 species of moths and butterflies, including numerous hairstreak butterflies and dagger, underwing, and silk moths. Two oaks recommended as excellent generalist species by Earth Sangha, a Northern Virginia conservation group, are the majestic white oak (Quercus alba) and fast-growing northern red oak (Quercus rubra). In general, oaks serve as shade trees for large yards and will require at least 1300 square feet for proper growth. Homeowners with smaller yards may want to consider dwarf chestnut oak (Quercus prinoides), which reaches 10 to 15 feet in height and begins producing acorns in three to five years.
Trees in the Prunus genus, ranked number two by Tallamy, support 456 Lepidoptera, including the spring azure and viceroy butterflies, as well as the cecropia, imperial, and polyphemus moths. While black cherry (Prunus serotina) is an important tree for the ecosystem, it may not be the best choice for smaller home landscapes. It reseeds prolifically and is often defoliated by tent caterpillars. In addition, amygdalin, a chemical it releases in its leaves, twigs, and seeds, is toxic to pets and may suppress the growth of other plants. Acceptable shorter trees in the Prunus genus are Chickasaw plum (P. angustifolia) and American plum (P. americana), which provide nectar and pollen from their fragrant flowers in early spring and edible fruit that ripens in June and July. Note that these trees are vigorous spreaders, making them excellent choices for screening, soil stabilization, and habitat for birds, but they would require regular pruning to maintain them as single-stemmed plants.
Plants in the Salix genus are larval hosts for 455 caterpillars and also support 14 species of mining and fairy bees, which are pollen specialists. Large black willow (Salix nigra) is not well-suited to home landscapes as its weak branches can be easily broken and its shallow, water-seeking roots may damage sewer lines and septic systems. Shrub-sized silky willow (Salix sericea), a multi-stemmed species of 7 to 12 feet, grows in a range of sun exposures and would do well in damp or wet areas of a yard. It can help to stabilize soil in areas prone to erosion and is a good choice for creating natural barriers or screening.
Other keystone trees for larger home landscapes include birches and hickories, which serve as larval hosts to 413 and 200 Lepidoptera, respectively. Examples are river birch (Betula nigra) with its spring catkins and striking exfoliating bark and mockernut hickory (Carya tomentosa) with its nutritious nuts and golden-colored fall foliage.
Unfortunately, plants in many of the top genera from Tallamy’s list are not well-suited to home landscapes. Some plants do not have a native range in the Mid-Atlantic or they may be subject to pests or diseases. See the handout accompanying the recorded presentation for details. One genus of smaller trees to consider is Crataegus, which supports 159 species of Lepidoptera. Cockspur hawthorn (Crataegus crus-galli), which grows 20 to 35 feet tall and wide, has abundant clusters of spring flowers that draw pollinators, and its red-orange fall fruit is both ornamental and a food source for birds.
The Wild Ones chart lists additional small keystone trees under 30 feet, including serviceberries (Amelanchier species) and dogwoods (formerly Cornus, now Bethamidia and Swida), known for both their showy spring flowers and fruit. Examples native to the Mid-Atlantic are downy serviceberry (Amelanchier arborea); pagoda dogwood (Swida alternifolia); and the Virginia state tree, flowering dogwood (Bethamidia florida). Wax myrtles and bayberries, including southern bayberry (Morella cerifera) and sumacs, such as staghorn sumac (Rhus typhina), are noted for their showy fruit. American hornbeam (Carpinus caroliniana) offers excellent nesting sites as well as nutlets for birds, while arborvitae (Thuja occidentalis) provides wildlife cover with its dense evergreen foliage. Larval host support for these genera ranges from 124 to 50 caterpillar species.
Keystone Shrubs and a Vine
Plants in the Vaccinium genus are the highest-ranking keystone shrubs in Tallamy’s list, hosting 288 Lepidoptera species, such as the Henry’s elfin, spring azure, and striped hairstreak butterflies. They also support seven pollen specialist bees and other pollinators with their floral resources and provide delicious fruit enjoyed by birds and humans alike. Highbush blueberry (Vaccinium corymbosum), with its brilliant fall foliage, makes a lovely specimen plant, or it can be grouped in a shrub border or along the edge of a woodland garden.
Native roses, such as Carolina Rose (Rosa carolina), host 139 species of butterflies and moths. Their large pink flowers draw bees and butterflies for pollen and nectar and then mature into red hips that are a source of food for songbirds and small mammals in fall and winter. These shrubs are ideal for use as a hedge that can offer wonderful year-round cover for wildlife, and their dead, hollow stems provide nesting habitat for native bees.
Hazelnuts in the Corylus genus support 131 caterpillar species, and American Hazelnut (C. americana) has been flagged by Earth Sangha as a high-value generalist shrub. In addition to its role as a larval host plant, its large leaves and thicket-forming habit provide excellent cover for nesting birds. Its egg-shaped nuts, which are produced after two to three years, are a preferred food for jays, woodpeckers, and small mammals.
Additional keystone shrubs from the Wild Ones list include plants in the Viburnum, Hamamelis, and Rhododendron genera, hosting 104, 63, and 21 Lepidoptera species, respectively. Examples native to the Mid-Atlantic include pinxterbloom azalea (Rhododendron periclymenoides) noted for its showy spring blossoms; arrowwood (Viburnum dentatum), which offers both floral resources and nutritious fruit; and witch hazel (Hamamelis virginiana), the latest-blooming native shrub with its unusual ribbon-like flowers.
Photo © Elaine Mills
A final woody plant to consider for the home landscape is trumpet honeysuckle (Lonicera sempervirens), a larval host to 36 caterpillar species, including the hummingbird and snowberry clearwing moths. This twining, semi-evergreen vine can be grown on arbors, trellises, and fences where its bright, whorled flower clusters will draw pollinating insects and hummingbirds for nectar. The orange-red fruit will be consumed by birds through the fall and winter.
Look for Part 2 of this article which will discuss the top herbaceous keystone plants for Lepidoptera.
A final woody plant to consider for the home landscape is trumpet honeysuckle (Lonicera sempervirens), a larval host to 36 caterpillar species, including the hummingbird and snowberry clearwing moths. This twining, semi-evergreen vine can be grown on arbors, trellises, and fences where its bright, whorled flower clusters will draw pollinating insects and hummingbirds for nectar. The orange-red fruit will be consumed by birds through the fall and winter
Resources
Keystone plants supporting Lepidoptera:
- Native Caterpillars, Moths, Butterflies, and Host Native Woodies, Wild Ones
- Tallamy, Douglas. Bringing Nature Home, Nature’s Best Hope,and The Nature of Oaks
Locally appropriate species:
- Compendium, Earth Sangha Wild Plant Nursery (general advice on planting natives)
- Digital Atlas of the Virginia Flora
- Maryland Native Plant Guide
- Maryland Plant Atlas
- Native Plant Finder, National Wildlife Federation (locate keystone plants by zip code)
- Native Plant Society of New Jersey, Plant Lists
- Native Plants for Delaware Landscapes
- Native Tree Choices, Plant NoVA Natives
- Oaks of the National Capital Region, National Park Service
- Pennsylvania Native Plant Society
- Plant Virginia Natives (regional native plant guides), including Native Plants for Northern Virginia