Crataegus monogyna, known as common hawthorn, oneseed hawthorn, or single-seeded hawthorn, is a species of hawthorn native to Europe, northwest Africa and West Asia. It has been introduced in many other parts of the world. It can be an invasive weed.
The common hawthorn is a shrub or small tree 5–14 metres (15 to 45 feet) tall, with a dense crown. The bark is dull brown with vertical orange cracks. The younger stems bear sharp thorns, approximately 12.5 mm (half an inch) long. The leaves are 20 to 40 mm (1 to 1½ inches) 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. Other common names of the plant include may, mayblossom, maythorn, quickthorn, whitethorn, motherdie, and haw.