Crataegus monogyna

Crataegus monogyna, known as common hawthorn, whitethorn, one-seed hawthorn, or single-seeded hawthorn, is a species of flowering plant in the rose family, Rosaceae. It grows to about 10 metres (33 feet) tall, producing hermaphrodite flowers in late spring. The berry-like pomes (known as haws) contain a stone-encased seed.

The plant is native to Europe, but has been introduced in many other parts of the world. The pome flesh is of little culinary interest due to its dryness, but is used to make jellies. The young leaves and petals are also edible.

The common hawthorn is a shrub or small tree up to about 10 metres (33 feet) tall, with a dense crown. The bark is dull brown with vertical orange cracks. The younger stems bear sharp thorns, about 12.5 millimetres (1⁄2 inch) long. The leaves are 20 to 40 mm (3⁄4 to 1+1⁄2 in) 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; they have numerous red stamens and a single style and are moderately fragrant. The flowers are white, frequently pink. They 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 10 mm long, berry-like, but structurally a pome containing a single seed within a stone, the pyrene. The haws develop in groups of two or three along smaller branches. They are pulpy and delicate in taste.

Its fruit persists for an average of 107.3 days, and bears an average of 2.8 seeds per fruit. Fruits average 75.7% water, and their dry weight includes 9.0% carbohydrates and 1.0% lipids.

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 the flowers having just one style, not two or three. They are interfertile, however, so hybrids occur frequently; they are only entirely distinct in their more typical forms. Another species that also hybridises with the common hawthorn is Crataegus rhipidophylla, which is distinguished by having finely instead of coarsely serrated lobe margins.

The pomes of some other hawthorns may have up to five seeds.

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. In 1793, Medikus published the name C. apiifolia for a European hawthorn now included in C. monogyna, but that name is illegitimate under the rules of botanical nomenclature.