Rhamnus cathartica

In buckthorn, umbels of flowers arise from leaf axils. Flowers on a single plant may be perfect (both male and female organs present), but more commonly the flowers are dioecious with either all male (staminate) or all female (pistillate) flowers found on any given plant. Individual flowers are 1/4″ across. They have four greenish-yellow, triangular, spreading sepals that together form a calyx and four petals that can’t be easily seen without magnification; the “petals” in the flowers are actually sepals. Male flowers have four greenish stamens with cream-colored anthers; female flowers have a single style that has a tip divided into four branches. After fertilization, female (or perfect) flowers produce a shiny black, 1/4″ wide, cherry-like fruit containing 3-4 seeds. Birds can eat the fruit without ill effects, but in humans the fruit produces stomach cramps and acts as a strong laxative (as indicated by the species name, “cathartica“).

Buckthorn leaves are (usually) opposite, oval or roughly egg-shaped, 1-2″ long and 3/4-1.5″ wide, hairless, with fine teeth that extend along the entire margin, dark green above, light green below, with a 1/2″ long, slender petiole. Buckthorn leaves retain their green color long into the autumn, much later than other trees. There are 2-3 lateral veins on either side of the midvein; the lateral veins are strongly curved so they are subparallel to the margins. Buckthorn was introduced to the US from Europe in the early 1800s, originally as a component of hedges and farm shelterbelts. Buckthorns secrete chemicals from their roots that suppress the growth of other plants; it thus tends to out-compete and displace native species. The fruits are much loved by birds (especially robins), which helps buckthorn spread further. The lakeshore between the south end of 57th St. Beach and the entrance to 59th St. Harbor is covered with “rip-rap” (large concrete and limestone slabs) to prevent erosion. In that approximately 50 yards of lakeshore, about 10% of the small trees are mulberry (another aggressive exotic), the other 90% are buckthorn. Buckthorn produces an orange hardwood said to be much prized by carvers, who should be encouraged by everyone who appreciates native ecosystems.

Buckthorn (aka, European buckthorn or common buckthorn) may grow as either a woody shrub or a small tree with one or more trunks up to 6″ in diameter that can grow up to 25 feet tall. The wood is dense and orange in color; the bark on the branches is brown, relatively smooth, and covered with small white lenticels; it roughens with age. The leaves are (usually) opposite, oval or roughly egg-shaped, 1-2″ long and 3/4-1.5″ wide, hairless, with fine teeth that extend along the entire margin, dark green above, light green below, with a 1/2″ long, slender petiole. Buckthorn leaves retain their green color long into the autumn, much later than other trees. There are 2-3 lateral veins on either side of the midvein; the lateral veins are strongly curved so they are subparallel to the margins. Umbels of flowers arise from leaf axils. Flowers on a single plant may be perfect (both male and female organs present), but more commonly the flowers are dioecious with either all male (staminate) or all female (pistillate) flowers found on any given plant. Individual flowers are 1/4″ across. They have four greenish-yellow, triangular, spreading sepals that together form a calyx and four petals that can’t be easily seen without magnification; the “petals” in the flowers are actually sepals. Male flowers have four greenish stamens with cream-colored anthers; female flowers have a single style that has a tip divided into four branches. After fertilization, female (or perfect) flowers produce a shiny black, 1/4″ wide, cherry-like fruit containing 3-4 seeds. Birds can eat the fruit without ill effects, but in humans the fruit produces stomach cramps and acts as a strong laxative (as indicated by the species name, “cathartica“). Buckthorn was introduced to the US from Europe in the early 1800s, originally as a component of hedges and farm shelterbelts. Buckthorns secrete chemicals from their roots that suppress the growth of other plants; it thus tends to out-compete and displace native specie