Rhamnus carthartica / Buckthorn Bark
Rhamnus cathartica, the buckthorn, common buckthorn or purging buckthorn, is a species of small tree in the flowering plant family Rhamnaceae. Rhamnus cathartica is shade-tolerant, moderately fast-growing and short-lived.
It 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, and is now naturalised in the northern half of the continent, and is classified as an invasive plant in several US states and in Ontario, Canada.