WHO KNEW Goldenrods Are Essential for Biodiversity?
WHO KNEW Goldenrods are Essential for Biodiversity?
Keystone species are those that balance the diversity of an ecosystem.
You’ve heard about wolves as a keystone species in the animal world and how their reintroduction helped restore vegetation in Yellowstone National Park after too-numerous elk and deer had over-browsed the plants there. But there are categories of keystone species in the plant world, too.
Entomologist Doug Tallamy has observed that, in the plant world, trees are the most important for insects. Oaks top the list, hosting larvae of 473 insect species. Among American herbaceous plants, goldenrods are the most important, as they host 125 insects – more than any other in the herbaceous family. Goldenrod is not native to Europe and is considered a weed there, as no insects native to Europe feed on goldenrod. Other keystone families of herbaceous plants are asters, sunflowers, and coneflowers.
This fall, fields and roadsides sport tall, handsome yellow goldenrods in full bloom, and most varieties will bloom for a long time. Their pollen is a major source of energy for late season native bees, and some bees require goldenrod pollen to feed their larvae. Their nectar fuels migrating butterflies. While the plants are falsely blamed for seasonal allergies, the actual cause is rag-weed, a shorter and less attractive plant, often found near roadsides; the pollen of goldenrods is too heavy to be airborne. There are about 100 types of goldenrod in the United States; about 30 of them are found in New England, according to the Native Plant Trust in MA. The plants are not particular about soil and water, but some goldenrods are more aggressive than others. Gardeners who wish to help reverse the decline of insect species can pick well-behaved goldenrod varieties (genus Solidago) that can be grown from seed or divisions. Here are four good choices: blue stem (S. caesia) and zig zag (S. flexicaulis) are both shade tolerant and fairly short. Others that prefer full sun are wrinkle-leafed goldenrod (S. rugosa) and gray goldenrod (S. nemoralus).