Rhamnus caroliniana Walter

Carolina Buckthorn


CC = 6
CW = 3
MOC = 49

© SRTurner

Family - Rhamnaceae

Habit - Shrub or rarely small tree, 2-5 m tall.

Stems - Main stems usually several, the branches all ascending and elongate, none of them armed. 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, simple, petiolate. 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, glossy, 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.

Rhamnus_caroliniana_leaves1.jpg Lateral stem and leaves.

© SRTurner

Rhamnus_caroliniana_leaf1.jpg Leaf adaxial.

© SRTurner

Rhamnus_caroliniana_leaf2.jpg Leaf abaxial.

© SRTurner

Rhamnus_caroliniana_leaf2a.jpg Leaf abaxial surface.

© SRTurner

Inflorescences - Small axillary clusters of 2-8 flowers, occasionally reduced to solitary flowers, the clusters with a stalk 3-10 mm long, the individual flower stalks 3-6 mm long.

Rhamnus_caroliniana_inflorescences.jpg Inflorescences.

© SRTurner

Rhamnus_caroliniana_inflorescence.jpg Inflorescence.

© SRTurner

Flowers - Perfect. Sepals 5, triangular, 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. Stamens 4 or 5 (abortive and shed early in pistillate flowers), not exserted. Ovary 2-4-locular (reduced and rudimentary in staminate flowers), unlobed, the style unbranched.

Rhamnus_caroliniana_flowers.jpg Flowers.

© SRTurner

Fruits - Globose drupes 7-10 mm long, with 3 stones, red at maturity, sometimes becoming black with age.

Rhamnus_caroliniana_fruits1.jpg Immature fruits.

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Rhamnus_caroliniana_fruits2.jpg Mature fruits.

© SRTurner

Flowering - May - June.

Habitat - Upland forests, streambanks, glades, bluffs, roadsides.

Origin - Native to the U.S.

Lookalikes - Other species of Rhamnus.

Other info. - This shrub is common in most southern Missouri counties, but appears to be absent or nearly so from nearly every county north of the Missouri River, as well as many western counties. Beyond Missouri its range is mostly confined within the southeastern quadrant of the continental U.S. The plant is identified by its alternate, elliptic leaves with glossy upper surfaces and a distinct pattern of 6-11 pairs of lateral veins. The flowers occur in leaf axils and are relatively inconspicuous.

This and other species of thornless buckthorn are often split into their own genus, under which classification this plant is named Frangula caroliniana.

Photographs taken at Rockwoods Reservation, St. Louis County, MO, 9-20-2010, Don Robinson State Park, Jefferson County, MO, 6-7-2017, and at Glassberg Conservation Area, Jefferson County, MO, 6-14-2019 and 8-5-2020 (SRTurner).