Sweet coneflower

Latin Name/Common Name- The name Rudbeckia was given to the black-eyed Susan family by Linnaeus in order to commemorate a Swedish father and son, both named Olaus (Olof) Rudbeck. The father was a professor of medicine, an excellent musician, linguist and botanist. He founded the Uppsala Botanic Garden. His son, Olof Rudbeck the Younger was also a distinguished professor of medicine at Uppsala, responsible for anatomy, botany, zoology and pharmacology. I found their story and connection with Linnaeus very interesting. In a nutshell, Olaf the Younger assisted his father with a monumental botanical work known as Campus Elysii, a survey of all plants known at the time with thousands of woodcut illustrations. Most of this life long work burned, along with notes and other related items in the terrible fire of 1702. I cannot imagine how devastating this must have been. Olof the Elder died only a few months later. The son continued their mission, only to have his work also destroyed in a fire. Years later, an impoverished Linnaeus came to Uppsala and was befriended by Olaf the Younger (now old). Linnaeus honored their relationship in 1753 by naming this beautiful genus for him.

The specific epithet ‘subtomentosa’ means below (sub) and hairy (tosa). Basically, it means 'somewhat' hairy. For example, Rudbeckia subtomentosa is less hairy than Rudbeckia hirta.

Sweet black-eyed Susan, the common name, comes from the flowers mild anise like scent.

Rudbeckia subtomentosa has petals of bright sunshine yellow with dark chocolate centers. Each flower is a composite of both disk and ray flowers. The yellow petals (ray flowers) are infertile while the dark brown to purplish center contains the fertile disk flowers. Each disk floret produces a single seed. The ray flowers number between 10 and 20. The width of ray florets varies plant to plant, with some being wide and others more narrow. The large flowers are about 3 inches wide.

Sweet black-eyed Susan is a hardy, long-lived perennial. It's taller than its 'cousin' Rudbeckia hirta, usually reaching about 4-5 ft tall. The stems are light green and covered with hairs. A single main stem branches several times toward the top of the plant. Each upper stem terminates in a single flower. There are many flowers per plant. 

The leaves appear alternately on petioles along the stem with upper leaves often lacking petioles. Leaves are rough to the touch with the underside of each being hairy (hence the term subtomentosa). Mid to lower stem leaves are usually 3 lobed with upper stem leaves having one lobe (although there is overlap). All leaves have a lanceolate shape with teeth along the edges.

The spent flowers are soon replaced with chocolate colored seed heads. The seeds are favored by many birds including Goldfinches, Juncos and Chickadees.

Rudbeckia subtomentosa has a lovely scent. I notice it most when I just walk by a patch instead of putting nose to flower.

According to Illinois Wildflowers, many kinds of insects visit the flowers for nectar. On Ozarkedge, the most common insects I find on the flowers are Scoliid and Mason wasps, Halictid bees (green sweat bees), Robber flies, syrphid flies, moths and caterpillars. The insect I've documented more than any other is the Scoliid wasp.

Other insect visitors-

Rudbeckia subtomentosa is typically found at the woodland edge and along stream banks in mesic habitat. While I’ve read this plant can be cultivated to take full sun, I haven’t observed this in nature. I expect it could grow in full sun as long as there is ample water. I’ve noticed in years of low rainfall, the plants often wilt and drop some of their flower buds.

While Natureserve lists Rudbeckia subtomentosa as G5 Secure, the state distribution map is concerning. Its known range includes midwestern states and a few east of the Mississippi River. Natureserve lists it as Critically Imperiled in Kentucky, Mississippi, Texas and Vulnerable in Wisconsin, Iowa, Kansas. All other states within its range show No Status Rank.

In Arkansas, Rudbeckia subtomentosa has a C-Value of 7 in the group of 4-7. "Typically matrix taxa in intact, stable habitats, with some limited ability to respond to destabilizing forces and repopulate areas from which they have been extirpated."

Take a look at the petals below and you will see that Rudbeckia subtomentosa is a favorite of many insects and caterpillars. It is a host plant for the caterpillars of several butterflies and moths- including the Silvery Checkerspot butterfly.