What Are Keystone Plants?

Keystone plants are the small subset of native species that support the majority of caterpillars and specialist native bees. Research from Dr. Doug Tallamy at the University of Delaware shows that only fourteen percent of native plants support ninety percent of butterfly and moth species. These plants form the backbone of local food webs.

They matter because: • Ninety-six percent of terrestrial songbirds rely on caterpillars to raise their young. • Many native bees are pollen specialists that depend on specific native plant genera.

Why Keystone Plants Matter in North Texas

North Texas, including Dallas and the Blackland Prairie, is part of Ecoregion 9: Great Plains. Keystone plant genera for this region have been identified through Tallamy’s Lepidoptera research and Jarrod Fowler’s specialist bee research. These plants support hundreds of caterpillar species and dozens of specialist bees, forming the food base for birds and other wildlife.

Texas-specific organizations reinforce this guidance. The Native Plant Society of Texas offers regionally tailored classes and plant databases. Texas Parks and Wildlife provides identification guides for native milkweeds and butterfly resources. The Lady Bird Johnson Wildflower Center maintains a comprehensive database of Texas natives suited to North Texas soils and climate.

Clarification: Ecoregions and USDA Hardiness Zones

North Texas is commonly described as USDA Zones 8a and 8b, which refer only to average winter minimum temperatures. These zones help gardeners

understand cold tolerance and planting times, but they do not describe ecological relationships.

Keystone plant research uses ecoregions rather than USDA zones. Ecoregions are defined by soils, geology, historic vegetation, and plant–insect relationships. Dallas and the Blackland Prairie fall within Ecoregion 9: Great Plains, the region used by the National Wildlife Federation and Dr. Doug Tallamy to identify keystone plant genera.

In practice:

• USDA Zones 8a and 8b tell you what will survive winter.
• Ecoregion 9 tells you which native plants support the most caterpillars, specialist bees, and wildlife.

Both apply to North Texas, but they answer different questions related to horticulture and ecology.

Top Keystone Plant Genera for North Texas

Great Plains, Ecoregion 9

Trees

• Quercus (Oaks): 253 caterpillar species • Prunus (Plums and Cherries): 222 caterpillar species • Salix (Willows): 214 caterpillar species and 20 specialist bees

Shrubs

• Vaccinium (Blueberries and Sparkleberry): 146 caterpillar species

Perennials

• Helianthus (Native Sunflowers): 58 caterpillar species and 89 specialist bees • Solidago (Goldenrods): High specialist bee support • Symphyotrichum (Asters): Strong Lepidoptera and bee support

Research-Based Educational Resources

All links below come from authoritative, science-reviewed organizations with strong relevance to North Texas.

• Native Plant Society of Texas: https://www.npsot.org
• Native Landscape Certification Program: https://www.npsot.org/native-landscape-certification-program
• Lady Bird Johnson Wildflower Center Native Plant Database: https://www.wildflower.org/plants
• Texas Parks and Wildlife Milkweed Identification Guide: https://tpwd.texas.gov/education/butterflies/milkweed-guide
• Texas A&M AgriLife Extension: https://agrilifeextension.tamu.edu
• National Wildlife Federation Native Plant Finder for the Great Plains: https://www.nwf.org/NativePlantFinder
• Keystone Plants by Ecoregion: https://www.nwf.org/Garden-for-Wildlife/About/Native-Plants/Keystone-Plants