By Steven Foster |
In my Eureka Nature column, August 16, 2012, in the Eureka Springs Independent Newspaper, I posed the question what’s in the name Leatherwood (as in Lake Leatherwood and Leatherwood Creek) and whether that name referred to a small shrub known as Leatherwood (Dirca palustris) or some other plant, person, or place. The plant had not been collected in Carroll County since the early 20th century. In fact it is absent for Carroll County in the new Atlas of the Vascular Plants of Arkansas a publication of the Arkansas Vascular Flora Project, just released a few weeks ago. The Atlas has county range maps for 2,892 species of vascular plants known from Arkansas. Of course, it reflects what we don’t know as much as what we do know. It presents the opportunity to fill gaps in knowledge. Trained field botanists working in Arkansas are an extremely rare species. There’s simply not legions of botanists doing systematic field botany and collecting herbarium specimens— dried, pressed, physical specimens — the scientific foundation for plant geography and taxonomy.
On Sunday May 4th, I was delighted to be invited to tag along with a small legion of botanists at Lake Leatherwood. Led by Theo Whitsel, long-time botanist with the Arkansas Natural Heritage Commission, a group of 12 “brain trust” leading botanical experts from Arkansas and Missouri, did a quick walk through Leatherwood trails just to see what might be there. It was a quick “drive-by” on their way to other locations such as the new Devil’s Eyebrow Natural Area in Benton County, just north of Eureka Springs off of Highway 62, a 2,000 acre research just dedicated a year ago on the cold, snowy morning of May 3rd 2013.
To my surprise, there along the edge of the Hyde Hollow drainage growing in the moist gravel at the edge of the creek was Dirca palustris, the Leatherwood shrub. I had been in that same location many times before, but just hadn’t noticed it. It’s non-showy flowers are among the earliest of the season, blooming long before the leaves unfold.
Leatherwood is a small shrub, about three feet tall; a member of the mezerum family (Thymelaeaceae) found along creek bottoms from New Brunswick, west to North Dakota, couth to Florida and Louisiana. It is found in northwest and southwest Arkansas, but is not particularly common anywhere. Dirca is the only North American genus of the largely tropical plant family to which it belongs. Dirca palustris is an obscure medicinal plant, which like other members of the mezerum family are better known for their toxicity than their medicinal benefits. The fruit is considered toxic, and the fresh root, applied to the skin causes blistering. Tiny doses of the fresh bark causes vomiting and diarrhea. It is among the most obscure American medicinal plants.
Naturalist-explorer C.S. Rafinesque (1783-1840) provides insights into the potential of Leatherwood in Medical flora, or Manual of the medical botany of the United States of North America. 2 vols. Philadelphia, Samuel C. Atkinson. In the first volume (pp: 158-161) he notes:
“The blossoms are scentless and appear very early in the Spring, as soon as the Maples blossoms, long before the leaves are unfolded. The bark is very tough, can hardly be broken, and tearing in long stripes is used as yet in many parts for ropes, a practice borrowed from the Indian tribes : the wood is also flexible. The berries are poisonous, children must avoid them : if eaten by mistake, an emetic must be resorted to. . . . When the bark is chewed it produces salivation, it is so tough that it cannot be reduced to powder, but forms only a kind of lint. The watery preparations are nearly inert.”
In another interesting twist to the Leatherwood, story is the work of the Kansas State University research team of Aaron J. Floden, Mark H. Mayfield and Carolyn J. Ferguson in 2009. A new, single population of “Dirca palustris” was collected in Kansas in 1997. As the researchers looked more closely at the plant, they discovered it was quite distinct from D. palustris, in fact in 2009 they named a new previously undescribed species—Dirca decipiens (meaning “deceptive”). Subsequently they conducted simultaneous surveys of flowering Leatherwood plants in Kansas, Missouri, and Arkansas. These field observations resulted in finding the newly named Dirca decipiens in both Benton and Carroll counties in Arkansas. It differs in producing larger fruits, without stalks, and hairy branchlets, among other features. In 2009, this rare plant was only known from three populations. Another major caveat is that it occurs on northeast facing bluffs and slopes above the valley floor in rather dry limestone habitats, rather than along creeks in rich wooded bottomlands, where one finds Dirca palustris. Dirca decipiens blooms about a week later, too (Florden, A.J., M.H. Mayfield, and C. J. Ferguson. A new narrowly endemic species of Dirca (Thymelaeaceae) from Kansas and Arkansas, with a phylogenetic overview and taxonomic synopsis of the genus” J. Bot. Res. Inst. Texas 3(2):485–499, 2009.
To my mind the mystery of where the name Leatherwood originated relative to the lake, park, and creeks of the same name is solved. No more speculation. Case closed.
Adapted and expanded from Steven Foster’s Eureka Nature column, Eureka Springs Independent Newspaper, August 16 2012 & May 7, 2014