What Is a Keystone Plant? (And 10 You Can Plant Right Now)

• Give A Shit About Nature
• April 13, 2026
• Backyard Habitat, Native Plants
• 0 Comments

Most of us were taught that all plants are more or less equal when it comes to supporting wildlife. A garden is a garden. Flowers attract bees. Trees give birds a place to perch. That is true as far as it goes, but an entomologist at the University of Delaware named Douglas Tallamy spent decades measuring just how unequal plants actually are, and what he found changes the way most people think about what to put in their yard.

His research showed that roughly 14% of native plant species support about 90% of butterfly and moth caterpillar species. The other 86% of plants, including most of what’s sold at nurseries and planted in landscaping across North America, support almost nothing in terms of insect life.

Those high-value plants, the ones doing most of the ecological heavy lifting, are what Tallamy calls keystone plants.

What makes a plant a keystone plant

The term comes from architecture. The keystone is the wedge-shaped piece at the top of an arch that holds the whole structure together. Remove it, and everything collapses. That is exactly what happens to local food webs when these critical plants disappear from a landscape.

Keystone are the plants that specific insects have co-evolved with over thousands or millions of years, the ones whose chemistry those insects’ digestive systems are calibrated to handle. A caterpillar that evolved eating oak leaves generally cannot eat an ornamental pear. The food web that depends on that caterpillar, the birds, the bats, the small mammals, collapses without the right plant in the right place.

Tallamy’s research found that landscapes without keystone plants support 70 to 75% fewer caterpillar species than landscapes that include them, even if those landscapes contain 95% of all other native plant genera. Keystone plants are not just helpful. They are load-bearing.

Keystone plants are not all trees

It is worth noting that while trees are often discussed first because of the sheer number of species they support, keystone plants include shrubs and herbaceous perennials too. This matters enormously for people who don’t have room for a large tree, or who are starting with container gardens or small urban plots. Even a pot of goldenrod on a balcony contributes meaningfully to the local food web.

The plants below are divided into categories by size so you can find something that fits your space regardless of how much room you have.

How to find your regional keystones

The specific plants that will do the most work in your yard depend on where you live. The National Wildlife Federation’s Native Plant Finder lets you enter your zip code and see which plants support the most wildlife species in your specific ecoregion. It is one of the most useful tools available for this kind of planning and takes about two minutes to use. Homegrown National Park also maintains a searchable keystone plant list by ecoregion. Both are free.

The plants below are among the highest-value keystone species across most of North America, though regional variation exists. Use the tools above to confirm which ones are most relevant for your location.

10 keystone plants worth adding to your yard

1. Oak (Quercus spp.)

Supporting over 500 species of caterpillars across most of North America, oaks are the single most ecologically productive plant genus on the continent. Tallamy has found that oaks are the most productive trees in 84% of North American counties. That is not a close contest. No other plant genus comes close.

The idea that oaks are too large or slow-growing to bother with is worth questioning. Pin oaks and red oaks grow relatively quickly, and smaller species like the dwarf chinkapin oak mature at 15 to 20 feet. If you have any room for a tree, a native oak is the highest-impact choice you can make for the wildlife in your neighborhood.

Good starting choices: white oak (Quercus alba), red oak (Quercus rubra), pin oak (Quercus palustris)

2. Black cherry (Prunus serotina)

Cherries and plums in the Prunus genus support over 450 caterpillar species, making them second only to oaks. Black cherry in particular is one of the most valuable wildlife trees in eastern North America, producing small dark fruits that over 40 bird species eat, while the foliage hosts an extraordinary array of moth and butterfly caterpillars.

It grows quickly for a native tree, often reaching 40 to 60 feet at maturity, with lovely white spring flowers and good fall color. It self-seeds, which some people find useful and others manage by removing seedlings.

3. Willow (Salix spp.)

Willows support 455 caterpillar species and are among the earliest-blooming woody plants in spring, providing critical pollen and nectar for bees emerging before much else is in flower. The common image of willows as large, wet-ground trees is accurate for some species, but several smaller, shrubby native willows, including pussy willow (Salix discolor) and shrub willow species, are manageable in average garden conditions.

If you have a low or damp area of your yard that is difficult to plant, a native willow is an excellent solution that will immediately become one of the most ecologically productive spots on your property.

4. Native birch (Betula spp.)

Birches support around 400 caterpillar species and bring additional value through their papery bark, catkins that feed birds in winter, and attractive multi-season interest. River birch (Betula nigra) is a particularly good garden choice, with exfoliating cinnamon-colored bark and better resistance to bronze birch borer than white birch. It tolerates a wide range of soil conditions.

5. Native blueberry (Vaccinium spp.)

Blueberries and their relatives in the Vaccinium genus support close to 300 caterpillar species and over a dozen specialist bee species that can only gather pollen from this genus. They produce fruit that birds go genuinely wild for in late summer, and their fall foliage is reliably brilliant red.

Highbush blueberry (Vaccinium corymbosum) works in most garden settings, while lowbush blueberry (Vaccinium angustifolium) is an excellent ground cover for sunny, acidic, well-drained areas. Both require acid soil, which is an important consideration before planting.

6. Goldenrod (Solidago spp.)

This is the most important perennial on this list. Goldenrod supports over 115 specialist bee species and more than 100 caterpillar species, making it the highest-value herbaceous plant in most North American gardens. It is also one of the most important late-season nectar sources for monarch butterflies fueling up for their southern migration.

It is also, famously, not the plant causing your fall allergies. That is ragweed, which blooms at the same time. Goldenrod’s pollen is heavy and sticky, carried by insects rather than wind. It is not an allergen.

For gardens: Solidago sphacelata ‘Golden Fleece’ is compact and well-behaved. Solidago caesia tolerates shade. Solidago rugosa ‘Fireworks’ has a spectacular arching form.

7. Native asters (Symphyotrichum spp.)

Asters support over 112 caterpillar and specialist bee species. They are among the most important plants you can grow for the critical fall nectar window, when pollinators and migrating butterflies are trying to build energy reserves before winter.

New England aster (Symphyotrichum novae-angliae) is adaptable, vigorous, and produces vivid purple-pink flowers in September and October. For shade, smooth blue wood aster (Symphyotrichum cordifolium) is excellent. Both self-seed gently and can be divided every few years to spread through a garden.

8. Native sunflowers (Helianthus spp.)

Native perennial sunflowers support around 70 caterpillar species and 50 specialist pollinators. They are not the annual garden sunflower most people picture. North America has over 50 native Helianthus species, many of them perennial, ranging from the tall and dramatic Maximilian sunflower to the more compact woodland sunflower.

They spread by rhizome, which is worth knowing before you plant, but in a meadow-style planting or a naturalistic border, they fill in beautifully and produce enormous quantities of seed that goldfinches and other birds harvest through the fall and winter.

9. Milkweed (Asclepias spp.)

Milkweed is the most well-known keystone plant in North America because of its relationship to monarch butterflies, whose caterpillars eat nothing else. But milkweed’s ecological value extends well beyond monarchs. The flowers support an enormous diversity of native bees, wasps, and butterflies, and the genus as a whole supports dozens of specialist insects.

Butterfly weed (Asclepias tuberosa) is the most garden-friendly species, with brilliant orange flowers and a compact form. Common milkweed (Asclepias syriaca) is the most ecologically productive but spreads vigorously, so give it space. Swamp milkweed (Asclepias incarnata) tolerates wet conditions and has lovely pink flowers.

10. Wild strawberry (Fragaria virginiana)

This one surprises people. Wild strawberry is one of the most important ground cover plants in North America for specialist bees, and it supports a meaningful number of caterpillar species while also producing fruit that birds eat eagerly. It spreads by runners to form a dense, low mat that suppresses weeds, provides habitat for ground-nesting bees, and stays green through most of the growing season.

It is one of the highest-value plants available for anyone with limited space, including containers. If you have a spot that gets reasonable sun and need a ground cover that does actual ecological work, wild strawberry is one of the best choices you can make.

A useful reframe

Most people approach garden planting by asking what looks good or what’s easy to grow. Those are reasonable questions, and keystone plants often satisfy both. But Tallamy’s research offers a different question worth asking first: what does the most work?

A single well-chosen oak tree does more for the food web in your neighborhood than an entire garden of ornamental plants that look beautiful but host almost nothing. That doesn’t mean beauty doesn’t matter. It means that when beauty and ecological value overlap, which with keystone plants they often do, that combination is worth prioritizing.

You don’t need a large property to make a difference. A container of goldenrod and asters on a city balcony supports specialist bees that will find nothing else for blocks in any direction. A single black cherry in a suburban yard feeds birds that would otherwise struggle to find enough caterpillars to raise their young.

Start with one. The rest tends to follow.

Frequently asked questions

What is the difference between a keystone plant and a native plant? All keystone plants are native plants, but not all native plants are keystones. Native plants are simply plants that evolved in a particular region. Keystone plants are the subset of native plants that support a disproportionately large number of other species. You can have an entirely native garden that still lacks keystone plants, which is why understanding the distinction matters.

How do I know which keystone plants are right for my region? Enter your zip code into the NWF Native Plant Finder or use the Homegrown National Park keystone plant tool. Both rank plants by the number of wildlife species they support in your specific area, which is far more useful than a generic national list.

Do I need a big yard to plant keystone species? No. Perennial keystones like goldenrod, asters, and wild strawberry work in small beds, borders, and containers. Even a few well-chosen plants in a small space contribute meaningfully to local insect populations.

Are cultivars of keystone plants as valuable as straight species? Generally somewhat less so, particularly cultivars with altered flower color or double flowers, which can reduce pollen and nectar availability. However, compact cultivars that are naturally occurring variations of straight species, rather than heavily engineered hybrids, tend to retain most of their ecological function. When in doubt, choose the straight species.

Where can I buy keystone plants? Look for native plant nurseries rather than big-box retailers, and ask whether plants are grown from locally sourced seed. Prairie Moon Nursery, Izel Plants, and Prairie Nursery are reputable mail-order sources. The Lady Bird Johnson Wildflower Center has a nursery finder by zip code for local sources.