Eastern leatherwood is a widely branching, usually several-stemmed shrub to 7 feet tall; if single-stemmed, the trunk can be 4 inches in diameter. It sometimes looks like a miniature tree.
Leaves are numerous, simple, alternate, oval to broadest above the middle, the tip blunt to somewhat pointed, the base narrowed or rounded, the margin entire, the blade 2–4 inches long, 2¾ inches wide; the surface hairy when immature, light green and smooth later, the lower surface with a whitish coat and somewhat hairy; the leaf stalk short, to ⅛ inch long, hairy, and hollow. The next year’s leaf buds are hidden and covered by the base of the leaf stalk.
Bark is mostly smooth and gray on old stems and roughened at the base of old trunks; very tough. Wood is soft, white, and brittle when dried.
Twigs are yellowish brown or reddish brown and smooth, stems ringed by circular scars at the beginning of the new growth. The twigs are very flexible and are capable of being bent or even tied into knots without breaking. They are enlarged at the joints.
Flowers late March–April, flowering before the leaves, the flowers falling off when the leaves expand. Flowers fairly abundant, occurring at the leaf axils, in clusters of 2–4 flowers. The flower tube is the calyx (joined sepals; petals are absent) and is about ¼ inch long, yellow, and unlobed, the margin merely irregular and/or with tiny scallops. Stamens 8. The stalks of the flower clusters are about ⅛–⅜ inch (2–7 mm) long at flowering, elongating to about ¼–½ inch (5–13 mm) at fruiting time. The stalks of individual flowers are smooth and up to about ⅜ inch (1–10 mm) long; sometimes 2 or more of these stalks are fused nearly to the tips. The persistent bracts at the base of the flower clusters are woolly-hairy on the undersurface with dense, dark brown (sometimes light or grayish brown) hairs.
Fruits May–June, sometimes hidden by the dense foliage, dropping early. The stalks are ⅛–⅜ inch long. Fruit usually pale green or yellowish, sometimes strongly tinged with red or purple, often turning darker and redder with age; oval to egg-shaped; ¼–⅜ inch long; smooth at the tip. Each fruit bears a single, dark brown seed.
Similar species: Leatherwood is a rather unusual, knobby-jointed shrub. Once you get to know it and have bent the twigs back a few times, you tend to remember it. Here are two relatives you may encounter in Missouri:
Ozark leatherwood (D. decipiens) is a recently described close relative of eastern leatherwood. It is uncommon in the southern half of the state, on bases and ledges of dolomite bluffs and steep slopes in moist upland forests. Because of its rarity and restriction to a fairly small region, it is ranked globally as imperiled. In Missouri it has been officially recorded from Gasconade and Oregon counties. Its Missouri distribution and abundance are still not well understood, so it may be more common in our state than initial reports indicate. Here are some of the ways to distinguish it from eastern leatherwood:
- Its twigs are hairy (not glabrous); the flower clusters are stalkless, or develop a stalk only to 1 mm long at flowering; this stalk does not elongate noticeably as the fruits mature.
- The individual flowers have hairy stalks to only about 2 mm long, even at fruiting time.
- The persistent bracts that subtend the flower/fruit clusters are hairy on the undersurface with white, gray, or light brown (not dark brown) hairs.
- The funnel-shaped or tubular calyx (joined sepals) has 4 irregular lobes 1–3 mm long, with the margins also irregular or minutely scalloped (not unlobed but merely irregular or minutely scalloped).
- Finally, the ovaries and fruits have an inconspicuous tuft of short hairs at the tip (not glabrous).
A native of Europe, spurge flax, or sparrow-wort (Thymelaea passerina), is in the same family. It has not been discovered in Missouri, but it has become established in several states, including Illinois, Wisconsin, Iowa, South Dakota, Nebraska, Kansas, Texas, Mississippi, Alabama, and Ohio. It is not likely to be confused with leatherwood. It is a nondescript, weedy species that is considered invasive in many states.
- It is not a shrub but is a tap-rooted, nonwoody annual. It has slender, upright, wiry stems that branch toward the top.
- Its leaves are alternate, narrow, and pointy-tipped.
- It spreads aggressively, and like other members of the family, it has bitter, toxic compounds that make it unpalatable to livestock, so it tends to increase in pastures and in disturbed soils.