See text Rhamnus is a genus of about 140 accepted species of shrubs or small trees, commonly known as buckthorns, in the family Rhamnaceae.

Its species range from 1 to 10 m (3 to 33 ft) tall (rarely to 15 m, 50 ft) and are native mainly in east Asia and North America, but found throughout the temperate and subtropical Northern Hemisphere, and also more locally in the subtropical Southern Hemisphere in parts of Africa and South America.

One species, the common buckthorn (Rhamnus cathartica), is able to flourish as an invasive plant in parts of Canada and the United States, where it has become naturalized.

[2] Rhamnus species are shrubs or small to medium-sized trees,[3] with deciduous or rarely evergreen foliage.

Rhamnus species are generally dioecious, with male and female flowers on separate plants.

Seeds are obovoid or oblong-obovoid shaped, unfurrowed or abaxially or laterally margined with a long, narrow, furrow.

The two plants are easy to distinguish by slowly pulling a leaf apart; dogwoods will exude thin, white latex strings, while buckthorns will not.

[13] The common buckthorn is well-adapted to spreading in Canada and the U.S.[1] It is an efficient grower that does not need much sunlight and or fertile soil.

R. cathartica was introduced into the United States as a garden shrub and has become an invasive species in many areas there.

[15] Italian buckthorn (R. alaternus), an evergreen species from the Mediterranean region, has become a serious weed in some parts of New Zealand,[16] especially on Hauraki Gulf islands.

In a 1930 study, both kerosene and salt were employed for eradication of R. lanceolata and both proved to be less expensive than felling these bushes.

[19] Another species, Avignon buckthorn (R. saxatilis) produces a yellow dye, made from the fruit Persian berry.