In Bloom: Wild Senna
By Suzanne Wodek, Asheville Botanical Gardens
Ethnobotany is a term frequently heard in talks I have attended lately. It is the study of traditional human uses of plants. I find the more I learn about the native people and flora of this diverse and beautiful place I call home, the more I become a better steward.
Take, for example, wild senna. The Native Americans applied a poultice of its crushed roots to external skin problems. They also drank an extract of the boiled roots to treat fevers.
Senna hebecarpa is a sturdy, long-lived upright-growing plant that forms a large bushy clump of dark green, lacy leaves. The large golden-yellow heads or spikes are stunning and provide an excellent cut flower for use in arrangements. The dark brown seedpods add interest to the winter landscape, as well.
Wild senna is an herbaceous native perennial member of the pea or legume family. Legumes are beneficial for their ability to fix atmospheric nitrogen—that is, creating compounds that help the plant grow and compete with other plants—thanks to a symbiotic relationship with rhizobia, a good soil bacteria. These plants help replenish soil with nitrogen, leading to stronger growth for other plants.
A unique specimen plant for borders, hedges, screening, meadows, and naturalizing, wild senna should be grown in soil that has good drainage in a sunny or partly shaded location. It grows naturally in damp, fertile soils and can reach a height of seven feet. In drier soils it will grow to about three feet.
As a backyard wildlife plant, it attracts butterflies, beneficial insects, hummingbirds, and songbirds. Often planted in 19th-century gardens, it is an underused perennial today and its chief fame in herbal circles is its effectiveness as a laxative.
The Botanical Gardens, located at 151 W.T. Weaver Boulevard, is a nonprofit organization housing a collection of plants native to the Southern Appalachian Mountains. Admission is free, but donations are appreciated and memberships are encouraged. Check ashevillebotanicalgardens.org for a variety of education programs this month.
This month at the Botanical Gardens at Asheville, join in a nature walk with garden manager Jay Kranyik Sunday, August 21, from 9–11 a.m. Participants must preregister and prepay. Member cost is $12, non-members, $17.