Family: Rhamnaceae, Buckthorn view all from this family
Description Also called Buckthorn, Common Buckthorn or Purging Buckthorn, this shrub is native to Europe, northwest Africa, and western Asia, from the central British Isles south to Morocco, and east to Kyrgyzstan. It was introduced to North America as an ornamental shrub in the early 19th century or perhaps before.
Rhamnus cathartica is a deciduous shrub or small tree growing up to 10 m tall, with grey-brown bark and spiny branches. The leaves are elliptic to oval, 2.5–9 cm long and 1.2–3.5 cm broad; they are green, turning yellow in autumn, and are arranged somewhat variably in opposite to subopposite pairs or alternately. The flowers are yellowish-green, with four petals; they are dioecious and insect pollinated. The fruit is a globose black drupe 6–10 mm diameter containing two to four seeds; it is mildly poisonous for people, but readily eaten by birds, which disperse the seeds in their droppings.
It is shade-tolerant, moderately fast-growing and short-lived. This species is a tough, durable tree which adapts to urban or suburban environments, and virtually any area it is dispersed in. It is widely regarded as a major invasive species whose shade prevents the establishment of native trees or shrubs.
It is a food plant of the Brimstone butterfly. The sulphur-yellow males are indicative of the plant's presence.
The species is naturalised and sometimes invasive in parts of North America. R. cathartica has a competitive advantage compared to native trees and shrubs in North America because it leafs out before native species. R. cathartica is also associated with invasive European earthworms (Lumbricus sp.) in the northern Midwest. Removing R. cathartica led to a decrease of invasive earthworm biomass of around 50%
Warning Bark and fruit 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.
Habitat Cities, suburbs & towns, Scrub, shrub & brushlands.
Range Great Lakes, Mid-Atlantic, New England, Southwest, Southeast, Plains, California, Rocky Mountains, Eastern Canada.
