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. It can be 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 5ń14 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 12.5mm (half an inch) long. The leaves are 20 to 40mm (1 to 1˝ 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. The hermaphrodite flowers are produced in late spring (May to early June in its native area) in corymbs of 5-25 together; each flower is about 10mm diameter, and has five white petals, numerous red stamens, and a single style; they are moderately fragrant. The flowers are pollinated by midges, bees and other insects and later in the year bear numerous haws. The haw is a small, oval dark red fruit about 10mm long, berry-like, but structurally a pome containing a single seed. Haws are important for wildlife in winter, particularly thrushes and waxwings; these birds eat the haws and disperse the seeds in their droppings. The common hawthorn is distinguished from the related but less widespread Midland hawthorn (C. laevigata) by its more upright growth, the leaves being deeply lobed, with spreading lobes, and in the flowers having just one style, not two or three. However they are inter-fertile and hybrids occur frequently; they are only entirely distinct in their more typical forms. Crataegus monogyna is one of the most common species used as the "hawthorn" of traditional herbalism. The plant parts used are usually sprigs with both leaves and flowers, or alternatively the fruit ("berries"). Hawthorne has been investigated by evidence-based medicine for treating cardiac insufficiency. Crataegus monogyna is a source of antioxidant phytochemicals, especially extracts of hawthorn leaves with flowers