1. Rhamnus caroliniana Walter (Carolina buckthorn, Indian cherry)

R. caroliniana var. mollis Fernald

Frangula caroliniana (Walter) A. Gray

Pl. 522 f, g; Map 2396

Plants shrubs or rarely small trees, 2–5(–12) m tall. Main stems usually several, the branches all ascending and elongate, none of them thorn-tipped. Bark gray to brown, sometimes with lighter blotches, shallowly furrowed on larger stems, relatively smooth. Twigs slender, green to reddish brown, becoming gray with age, glabrous to densely short-hairy, the winter buds slender, naked, reddish brown, densely and minutely hairy. Leaves alternate (occasionally a few appearing subopposite), the petioles 6–20 mm long. Leaf blades 3–12 cm long, 2–3 times as long as wide, rounded or broadly angled at the base, angled or slightly tapered to a bluntly or sharply pointed tip, the upper surface green to dark green, glabrous or occasionally minutely hairy along the midvein, shiny, the undersurface light green, glabrous to densely and minutely hairy, especially along the veins, the lateral veins mostly 6–11 pairs, these straight or slightly curved, mainly toward their tips. Inflorescences axillary, small clusters of 2–8 flowers or occasionally reduced to solitary flowers, the clusters with a stalk 3–10 mm long, the individual flower stalks 3–6 mm long. Flowers perfect. Sepals 5, 1.3–2.0 mm long, often white to greenish white on the upper surface. Petals 5, 1.0–1.5 mm long, broadly obovate, notched at the tips. Style unbranched. Fruits 7–10 mm long, globose, with 3 stones, red at maturity, sometimes becoming black with age. May–June.

Scattered in the Ozark and Ozark Border Divisions and in the Crowley’s Ridge and Sikeston Ridge portions of the Mississippi Lowlands (southeastern U.S. west to Missouri and Texas). Mesic to dry upland forests, banks of streams and rivers, glades, and ledges and tops of bluffs; also roadsides.

Plants in the western portion of the species range with relatively densely and persistently hairy leaves have been segregated as var. mollis. Steyermark (1963) accepted this taxon with great hesitation, noting that the two variants are not clearly distinct in Missouri, with all gradations of pubescence present in the state. The species is treated as a single variable taxon in the present account.

The superficially similar glossy false buckthorn (European alder-buckthorn), R. frangula L. (Frangula alnus Mill.) is widely naturalized in the United States, including several states adjoining Missouri (Nebraska, Iowa, Illinois, Kentuicky, and Tennessee). This aggressive, exotic invader of wetlands is native to Europe, but has escaped from cultivation in North America, Asia, and Africa. It differs from R. caroliniana in its somewhat shorter (4–8 cm) leaves with the blades mostly less than twice (vs. two to three times) as long as wide and with the margins entire or at most with a few, minute, glandular teeth near the tip, as well as its flower stalks and hypanthia glabrous or nearly so (vs. hairy). Botanists should watch for this species in the future, particularly in northern Missouri wetlands.