Keystone Plants – The Key to Healthy Ecosystems
By Pam Rosendal, Colorado Master Gardener
In recent decades, habitat loss has become one of the most pressing threats to animal populations around the world. Urbanization, intensive agriculture and the spread of non-native plant species have dramatically altered natural ecosystems, stripping animals of the essential resources they need to survive. As meadows are paved over and forests give way to development, many insect species – especially pollinators like bees, butterflies and moths – find themselves with fewer food sources, breeding grounds and shelter. This loss of insect life has a drastic impact on entire ecosystems, affecting birds, mammals and even humans who rely on pollinators for food production. Amid all this gloom, one vital yet often overlooked solution lies in the power of keystone native plants.
Keystone plants are native species that play a disproportionately important role in supporting local ecosystems. Much like a keystone holds an arch together, these plants sustain a wide variety of insects, particularly the caterpillars of native butterflies and moths, which are foundational to food webs. According to research by entomologist Dr. Doug Tallamy, just 14% of native plant species support over 90% of the caterpillar species in any given area. Jarrod Fowler, a horticulture researcher, reports that 15% to 60% of North American native bee species are pollen specialists who eat pollen from only 40% of native plants. These keystone plants are indispensable because they provide the specific food resources many insects require to complete their life cycles – resources that non-native ornamentals simply can’t equal.
The reason keystone native plants are so effective lies in their long evolutionary history with local wildlife. Over thousands of years, insects have developed intricate relationships with certain plant species. For example, oak trees (genus Quercus) are considered keystone species in much of North America because they host more than 500 species of caterpillars, not to mention all the animals that eat the acorns. Without these caterpillars, birds would struggle to find the nutrient-rich food their babies need to grow. (It takes 5,000 to 9,000 insects to raise one brood of chickadees.) Similarly, goldenrods, native willows and native sunflowers support a high diversity of pollinators and other insects. When these keystone plants disappear, the entire food web unravels.
Native plants are crucial for caterpillars because they have
specific host plants to feed on. Many insects visit flowers for
pollen/nectar (some specialists and some generalists),
but the caterpillar host plants are critical
for butterflies and moths to survive.
Incorporating native plants into our gardens is a powerful step toward reversing habitat loss and supporting biodiversity. Some plants play a singular role for one or limited species of wildlife as in monarch butterflies’ reliance on milkweed. Other keystone plants are essential to the life cycle of many species. Keystone plants are unique to local food webs within ecoregions (areas that share similar ecosystem characteristics like weather, soil type, seasons, etc.). By choosing to plant keystone natives from the local ecoregion, homeowners can help create high-quality habitats that actively support life by feeding caterpillars, attracting pollinators and nurturing the birds and mammals that depend on those insects.
As more people become aware of the role their landscapes play in the broader ecosystem, the demand for native plants is growing. Nurseries and conservation groups are increasingly offering keystone species to the public, making it easier for individuals to make environmentally conscious choices. Whether it is planting an oak in your yard, establishing a patch of Black-eyed Susan for pollinators or a single pot of goldenrod on a balcony, every keystone plant added to the landscape is a step toward rebuilding the web of life. In a world where insect populations are in sharp decline, keystone native plants offer a beacon of hope and a practical path toward ecological resilience.
Resources
- To learn more, visit Dr. Tallamy’s Homegrown National Park website and the National Wildlife Federation, which offer abundant information about native plant habitats including lists of keystone plants for our Great Plains ecoregion.
- Search by zip code for native plants most used by caterpillars in your area:
- Learn more about moths and butterflies in your area:
- Visit ButterfliesAndMoths.org.
- Find your county or state list of moths and butterflies here by using the filter search.
- Search for specific species to learn more about the caterpillar host plants, adult nectar plants, geographical range, and more.
- This fact sheet has a list of caterpillar host plants for common butterflies in Colorado.
