Dirca is a small genus of three or four species of deciduous shrubs in the family Thymelaeaceae (order Malvales), native exclusively to North America. The genus is best known by its common name leatherwood, a reference to the remarkably pliable stems and bark that is nearly impossible to tear by hand. Other common names include moosewood, ropebark, and wicopy — the last derived from the Powhatan language and reflecting the plant's traditional use as a source of fiber.
Members of the genus typically grow to a maximum height of around three metres and are found in rich, moist woodland settings, often on slopes above creeks or streams. The inner bark contains cross-linked fibers that are short but strong and flexible, which made the stems valuable to Native American peoples of eastern North America for binding and cordage. The genus also contains phenolic glycosides unique among flowering plants, and the bark and leaves carry calcium oxalate crystals that can cause severe contact dermatitis.
The most widespread species, Dirca palustris, ranges across eastern North America from Nova Scotia west to North Dakota and south to Florida. Dirca occidentalis has a much more restricted range, occurring in several counties of the San Francisco Bay area in California. Two additional species have been described more recently: D. mexicana, known from a single population in northeastern Mexico, and D. decipiens, described in 2008 from populations in Kansas and Arkansas. Dirca palustris is occasionally grown in cultivation, though its slow growth has limited its popularity in horticulture.
Etymology
The genus name Dirca derives from Dirce, a figure in Greek mythology. Its most widely used common name, leatherwood, alludes to the tough, pliable quality of the stems and bark. Additional common names include moosewood, ropebark, and wicopy — the last borrowed from the Powhatan language and referring to the plant's traditional use as a source of fiber; wigub is the Algonquin equivalent.
Distribution
Dirca is distributed across North America. D. palustris occurs throughout much of eastern North America, from Nova Scotia west to North Dakota and Oklahoma and south to Florida. D. occidentalis is restricted to several counties in the San Francisco Bay area of California. D. mexicana is known from a single population in northeastern Mexico, and D. decipiens, described in 2008, occurs in Kansas and Arkansas at the southwestern edge of the D. palustris range.
Ecology
Plants in this genus are typically found in rich, moist woods and on shaded slopes above creeks and streams. Dirca palustris frequently grows alongside spicebush (Lindera benzoin), which shares a similar early-spring flowering phenology. The bark and leaves contain calcium oxalate crystals and can cause severe contact dermatitis; the berries may have narcotic properties, though this is unsubstantiated. The genus produces phenolic glycosides not found elsewhere in the plant kingdom. Native peoples used the inner bark tea medicinally, though even small doses cause burning of the tongue and salivation.
Cultural Uses
Native Americans, including the Ojibwe, used the exceptionally strong and flexible stems of Dirca as thongs and ropes. The inner bark was brewed as a tea and used as a laxative in traditional medicine, though caution was exercised given its irritant properties. The Powhatan name wicopy specifically references the plant's role as a fiber source. Modern use is limited primarily to occasional cultivation of D. palustris as a slow-growing ornamental shrub.
