Keystone Native Plants by Region

The concept of keystone plants in horticulture comes directly from ecology research, specifically the work of entomologist Doug Tallamy, whose data -- compiled over more than two decades -- quantifies which native plant genera support the greatest number of caterpillar species, which are the base.

—- title: "Keystone Native Plants by Region" slug: best-plants-for-keystone-species hub: plants category: "Plant list" description: "Keystone native plants support the most species in each region's food web. This guide covers the top genera by region — Northeast, Southeast, Midwest, Southwest, Pacific Northwest — with zones, light, and height." date: 2026-06-10 updated: 2026-06-10 author: "Thomas A." reading_time: 10 —-

The concept of keystone plants in horticulture comes directly from ecology research, specifically the work of entomologist Doug Tallamy, whose data — compiled over more than two decades — quantifies which native plant genera support the greatest number of caterpillar species, which are the base of most terrestrial food webs. Per Tallamy and Shropshire's 2009 paper published in Ecological Entomology, which forms the empirical basis of the keystone plant concept, the distribution of caterpillar species among host plants is highly skewed: a small number of plant genera support the vast majority of caterpillar species, and most native plant genera support relatively few.

Per Tallamy's data as summarized by Penn State Extension, oaks alone support over 500 caterpillar species in the eastern U.S. Native cherries and plums support over 450. Willows support over 450. By contrast, many popular landscape plants — Japanese maples, Bradford pears, crape myrtles — support fewer than five species each. The implication for home gardeners is significant: a single native oak planted in a suburban yard provides more ecological function per tree than dozens of ornamental non-natives.

I live in zone 7a on Long Island, and the oaks, native viburnums, and serviceberries I've observed in my neighborhood support visibly higher bird and insect diversity than the yards dominated by non-native ornamentals. Whether you're in the Northeast, Southeast, Midwest, Southwest, or Pacific Northwest, the keystone genera — the plants that carry the most food-web weight in your region — differ, and knowing which ones to prioritize is the most efficient approach to restoring ecological function to a managed landscape.

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How to Use This Guide

Plants are organized by region, then by ecological value (number of caterpillar species supported, per the Tallamy lab's data at University of Delaware). For each plant, zones, light requirements, and mature height are from primary sources. "Lepidoptera supported" counts are from Tallamy and Shropshire 2009 and subsequent updates.

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Northeast and Mid-Atlantic (Zones 4–7)

1. Quercus spp. (Oaks)

Zones 3–9 (species-dependent) | Full sun | Height: 40–80 ft

Per Penn State Extension, oaks support more Lepidoptera species than any other plant genus in the eastern U.S. — over 500 caterpillar species depend on them, including many specialist moths that have no alternative host. Native oaks for the Northeast include Quercus alba (white oak, zones 3–9), Q. rubra (red oak, zones 4–8), Q. bicolor (swamp white oak, zones 3–8), and Q. palustris (pin oak, zones 4–8). Per Missouri Botanical Garden, all native oaks produce acorns that support dozens of bird and mammal species simultaneously. Even a young oak with a 4-inch trunk provides measurable habitat value.

2. Prunus spp. (Native Cherries and Plums)

Zones 2–8 (species-dependent) | Full sun | Height: 15–30 ft (shrub to small tree)

Per Tallamy and Shropshire 2009, native cherries and plums support 456 caterpillar species in the eastern U.S. — second only to oaks. Prunus serotina (black cherry, zones 3–9) is the highest-value species; P. virginiana (chokecherry, zones 2–7) performs similarly and stays smaller. Per NC State Extension, black cherry grows in full sun to part shade, reaches 60–80 ft at maturity, and its fruit supports at least 33 bird species per documented ornithological surveys.

3. Betula spp. (Native Birches)

Zones 2–7 (species-dependent) | Full sun to part shade | Height: 30–70 ft

Per Penn State Extension, native birches support 413 caterpillar species in the eastern U.S. Betula nigra (river birch, zones 4–9) is the most heat-tolerant and is native to floodplains from New England to Florida. B. papyrifera (paper birch, zones 2–6) is better adapted to northern sites with cool summers. Per UMN Extension, river birch tolerates periodic wet feet, making it useful in rain garden buffer zones and moist low-lying areas where other trees fail.

4. Salix spp. (Native Willows)

Zones 2–8 (species-dependent) | Full sun | Height: 6–50 ft (shrub to tree)

Per Cornell Cooperative Extension, native willows support over 450 Lepidoptera species — the third-highest count in the eastern U.S. For smaller landscapes, shrub willows (Salix discolor, pussy willow, zones 4–8; S. humilis, prairie willow, zones 4–6) provide keystone function without the size commitment of tree willows. Per Missouri Botanical Garden, willows require moist soil and are best placed in low spots, rain garden margins, or pond edges where their water demand can be naturally met.

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Southeast (Zones 7–9)

5. Quercus virginiana (Live Oak)

Zones 7–10 | Full sun | Height: 40–60 ft

Per UF IFAS Extension, live oak is the dominant keystone tree of the Gulf and Atlantic coastal plain. It is evergreen in zones 8–10, semi-evergreen in zone 7. Its leaf litter, acorns, bark, and canopy structure support a documented community of hundreds of insect species. Per Clemson HGIC, it is one of the most storm-resistant trees in the Southeast, with a dense, spreading canopy that provides exceptional wildlife habitat value alongside landscape function.

6. Celtis laevigata (Sugarberry / Southern Hackberry)

Zones 5–9 | Full sun to part shade | Height: 40–80 ft

Per Texas A&M AgriLife Extension, sugarberry is native to the bottomlands and floodplains of the southeastern and south-central U.S. It supports over 40 caterpillar species, including several specialist butterflies (hackberry emperor, tawny emperor, snout butterfly). Per UF IFAS Extension, its fruit — small orange-to-purple drupes — is consumed by at least 25 bird species. It tolerates poor drainage, heat, and drought once established, making it one of the most resilient large natives for southern landscapes.

7. Myrica cerifera (Wax Myrtle)

Zones 7–11 | Full sun to part shade | Height: 6–15 ft

Per Clemson HGIC, wax myrtle is native to coastal plain habitats from New Jersey to Florida and west to Texas. It supports a range of specialist insects and produces waxy berries that are a critical fat-rich food source for fall and winter migrating songbirds, particularly yellow-rumped warblers. Per NC State Extension, it tolerates salt spray, wet soil, and dry sandy soil — a rare combination that makes it uniquely useful in coastal southeastern landscapes.

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Midwest (Zones 4–6)

8. Quercus macrocarpa (Bur Oak)

Zones 3–8 | Full sun | Height: 60–80 ft

Per UMN Extension, bur oak is the most drought-tolerant and fire-resistant of the eastern oaks and was historically the dominant tree of the prairie-forest edge from Minnesota to Texas. It supports the same high caterpillar diversity as other oaks per Tallamy's data, and its large acorns are a primary food source for deer, turkeys, squirrels, and wood ducks. Per Missouri Botanical Garden, it tolerates clay, alkaline soil, and drought — three conditions that challenge most other large native trees.

9. Celtis occidentalis (Common Hackberry)

Zones 2–9 | Full sun | Height: 40–60 ft

Per UMN Extension, common hackberry is among the most ecologically productive trees in the Midwest, supporting over 40 caterpillar species as a host plant and producing fruit that 48 bird species consume per documented surveys. It tolerates alkaline soil, clay, drought, and urban air quality better than most native trees. Per Illinois Extension, hackberry is a genuinely underused street and park tree that deserves much wider planting given its wildlife support value.

10. Andropogon gerardii (Big Bluestem)

Zones 3–9 | Full sun | Height: 4–8 ft

Per Missouri Botanical Garden, big bluestem is the dominant grass of the tallgrass prairie and one of the highest-value plants for Midwest ecosystem function. It supports specialist insects tied to native grasses — skippers, grasshoppers, and stem-nesting bees — and its persistent winter seed heads and stem structure provide overwintering habitat for native bees, beneficial wasp species, and small mammals. Per USDA NRCS, it develops an 8–10 ft root system over time, contributing to deep carbon storage and drought resilience.

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Southwest (Zones 6–10)

11. Quercus gambelii (Gambel Oak)

Zones 4–8 | Full sun | Height: 15–30 ft

Per Texas A&M AgriLife Extension, Gambel oak is the keystone oak of the southern Rocky Mountain region, dominating mid-elevation shrublands from Colorado to Arizona. It supports a full community of specialist Lepidoptera and its acorns are the primary fall food source for mule deer, black bears, and band-tailed pigeons in its range. Per USDA NRCS, it spreads by rhizome and often forms dense multi-stemmed thickets rather than single-trunk trees — this thicket form is itself high-value bird nesting habitat.

12. Prosopis glandulosa (Honey Mesquite)

Zones 6–11 | Full sun | Height: 15–30 ft

Per Texas A&M AgriLife Extension, honey mesquite is a keystone species of the Chihuahuan and Sonoran desert grasslands, providing food (pods, flowers), cover, and nesting structure for over 100 documented bird and mammal species. Its fragrant flowers are a primary spring nectar source for native bees in the Southwest. Per USDA NRCS, it is drought-adapted with a taproot that can reach 150–200 ft depth in deep soils. It is considered invasive in some range management contexts, but for established urban and suburban gardens in its native range it is irreplaceable.

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Pacific Northwest (Zones 6–9)

13. Quercus garryana (Oregon White Oak / Garry Oak)

Zones 6–9 | Full sun | Height: 40–70 ft

Per Oregon State Extension, Garry oak is the only native oak of the Pacific Northwest and one of the most endangered ecosystem types in the region due to fire suppression and development. It supports over 200 insect species as a host plant and provides acorns that are a primary food source for Steller's jays, band-tailed pigeons, and acorn woodpeckers. Per USDA NRCS, it grows slowly — 1–2 ft per year when young — and tolerates summer drought once established, which is critical for Pacific Northwest gardens that receive little summer rainfall.

14. Acer circinatum (Vine Maple)

Zones 5–8 | Part shade to full shade | Height: 15–25 ft

Per Oregon State Extension, vine maple is a native understory tree of Pacific Northwest forests and one of the most productive host plants in the region for Lepidoptera diversity. It tolerates deep shade under Douglas fir and western red cedar canopy, making it uniquely useful for forested suburban lots where most natives fail from lack of light. Its seeds are consumed by small mammals and birds, and its dense multi-stemmed form provides nesting structure for multiple songbird species.

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Frequently Asked Questions

How do I choose between planting one large keystone tree versus multiple smaller native plants?

Per Penn State Extension's applied research on Tallamy's work, a single native oak supports more Lepidoptera species than any combination of smaller native plants you are likely to fit in the same space. If your lot has room for a canopy tree, the most ecologically efficient choice is planting the highest-value keystone tree native to your region. Small shrubs, grasses, and forbs are more valuable in sites where canopy trees are not feasible, or as understory additions beneath an existing keystone tree.

Do non-native cultivars of native species (e.g., red-leafed oaks, dwarf cultivars) have the same keystone value?

Per Xerces Society, research on this is ongoing but the evidence so far suggests that cultivars with altered leaf chemistry — particularly red-leafed or anthocyanin-enhanced cultivars — support significantly fewer caterpillar species than the straight species. Dwarf cultivars of the same species tend to retain most of the host plant chemistry, though their reduced leaf area limits the total caterpillar population they can support. Straight species or straight-species cultivars with green foliage are recommended where ecological function is the priority.

How many years does it take for a newly planted keystone tree to provide meaningful wildlife habitat?

Per Missouri Botanical Garden, even young trees with trunk diameters of 1–2 inches support Lepidoptera larvae from their first season in the ground. The population they support scales with crown size — a mature oak with 1,000 square feet of canopy supports far more caterpillars than a 3-ft whip, but the value begins immediately. Per Penn State Extension, the common advice to wait until a tree is "established" before it provides habitat is wrong; ecological function begins at planting.

What if I can only plant shrubs — are there keystone shrubs?

Yes. Per Tallamy's data, Salix (willow) shrub species, Prunus shrub species (chokecherry, beach plum), native Vaccinium (blueberry, huckleberry), and Celtis (hackberry, where available as a large shrub) all rank among the top Lepidoptera-supporting genera. Native viburnums and serviceberries (Amelanchier spp.) are also highly productive relative to their size. These are viable alternatives when canopy tree planting is not feasible.

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Sources

1. Tallamy & Shropshire — Ranking Lepidopteran Use of Native Versus Introduced Plants
2. Penn State Extension — Keystone Plants for Wildlife
3. Missouri Botanical Garden — Plant Finder
4. UF IFAS Extension — Live Oak
5. Clemson HGIC — Wax Myrtle
6. Texas A&M AgriLife Extension — Native Trees of Texas
7. Oregon State Extension — Oregon White Oak
8. UMN Extension — Bur Oak
9. UMN Extension — River Birch
10. Illinois Extension — Hackberry
11. NC State Extension — Prunus serotina
12. USDA NRCS — Plant Materials Program
13. Cornell Cooperative Extension — Native Trees and Shrubs
14. Xerces Society — Native Plant Recommendations