Crataegus monogyna, known as common hawthorn or single-seeded hawthorn, is a species of hawthorn native to Europe, northwest Africa and western Asia. It has been introduced in many other parts of the world where it is an invasive weed. Other common names include may, mayblossom, maythorn, quickthorn, whitethorn, motherdie, and haw. This species is one of several that have been referred to as Crataegus oxyacantha, a name that has been rejected by the botanical community as too ambiguous.
The Common Hawthorn is a shrub or small tree 5-14 m tall, with a dense crown. The bark is dull brown with vertical orange cracks. The younger stems bear sharp thorns, 1 to 1.5 cm long. The leaves are 2- 4 cm long, obovate and deeply lobed, sometimes almost to the midrib, with the lobes spreading at a wide angle. The upper surface is dark green above and paler underneath.