Alternate name: Glossy False Buckthorn
Family: Rhamnaceae, Buckthorn view all from this family
Description Also called alder buckthorn, this tall deciduous shrub is native to Europe, northernmost Africa, and western Asia. It is also introduced and naturalised in eastern North America.
Alder Buckthorn is a deciduous shrub, growing to 3–6 m, occasionally to 7 m tall. It is usually multistemmed, but rarely forms a small tree with a trunk diameter of up to 20 cm. The bark is dark blackish-brown, with bright lemon-yellow inner bark exposed if cut. The shoots are dark brown, the winter buds without bud scales, protected only by the densely hairy outer leaves The leaves are ovate, 3–7 (–11) cm long by 2.5–4 (–6) cm wide, slightly downy on the veins, with an entire margin, 6–10 pairs of prominently grooved veins, and an 8–15 mm petiole; they are arranged alternately on the stems. The flowers are small, 3–5 mm diameter, star-shaped with five greenish-white acute triangular petals, hermaphroditic, and insect pollinated, flowering in May to June in clusters of two to ten in the leaf axils. The fruit is a small black berry 6–10 mm diameter, ripening from green through red in late summer to dark purple or black in early autumn, containing two or three pale brown 5 mm seeds. The seeds are primarily dispersed by frugivorous birds, which readily eat the fruit.
Alder Buckthorn grows in wet soils in open woods, scrub, hedgerows and bogs, thriving well in sunlight and moderate shade, but less vigorously in dense shade; it prefers acidic soils though will also grow on neutral soils.
Frangula alnus is one of just two food plants (the other being Rhamnus cathartica) used by the Common Brimstone butterfly Gonepteryx rhamni. The flowers are valuable for bees, and the fruit an important food source for birds, particularly thrushes.
Frangula alnus was probably introduced to North America about 200 years ago, and in Canada about 100 years ago. It was planted for hedgerows, forestry plantings, and wildlife habitat, but has become an invasive species, invading forests in the northeastern United States and wetlands and moist forest in the Midwestern United States. It is predicted to continue to expand its North American range with time. Its invasiveness is assisted by its high adaptability and pollution tolerance.
It invades forests and grows in the understory in spots with a lot of light. Uplands forests are not invaded as easily as lower lying ones.
Warning Bark and fruit have been used medicinally but can be toxic to humans if ingested; fatalities are very rare. Sensitivity to a toxin varies with a person’s age, weight, physical condition, and individual susceptibility. Children are most vulnerable because of their curiosity and small size. Toxicity can vary in a plant according to season, the plant’s different parts, and its stage of growth; and plants can absorb toxic substances, such as herbicides, pesticides, and pollutants from the water, air, and soil.
