T.E.R:R.A.I.N - Taranaki Educational Resource: Research, Analysis and Information Network

Crataegus monogyna (Hawthorn)

Kingdom: Plantae
(Unranked): Angiosperms
(Unranked): Eudicots
(Unranked): Rosids
Order: Rosales
Family: Rosaceae
Genus: Crataegus
Series: Crataegus
Species: C. monogyna
Binomial name: Crataegus monogyna
Common names: Common Hawthorn, Hawthorn, Haw, Thornapple, Maythorn, Whitethorn, Single-seeded hawthorn, May, Mayblossom, Quickthorn, Motherdie.

Crataegus monogyna is a thorny, much-branched, deciduous shrub or small tree 5–14 m tall, with a dense crown and 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. It is found widespread throughout New Zealand in hedges, poor pastures, roadsides, and waste places. It prefers distinct seasons with cold winters. 
It classed as a weed because it crowds out most other species by forming dense (occasionally pure) thickets, preventing the establishment of native plant seedlings. It produces many long-lived, well dispersed seeds, is extremely tough and versatile, long-lived, tolerates hot to cold temperatures, damp to dry conditions, salt, wind, heavy damage, most soils, and semi-shade.
The younger stems bear sharp thorns, 12 mm long. The bark is dull brown with vertical orange cracks.
The hairless triangular leaves are 2–4 cm long, obovate and deeply lobed, sometimes almost to the midrib, with the lobes spreading at a wide angle. They are solitary on long shoots, clustered on short shoots. The leaves upper surface is dark green above and paler underneath.
The hermaphrodite sweet-scented flowers (10-15 mm diameter) are produced in October and November, in corymbs of 5-25 together. Each flower is about 1 cm diameter, and has five white petals (rarely reddish-pink), numerous red stamens, and a single style; they are moderately fragrant. They are pollinated by midges and later in the year bear numerous haws from December to April. The haw is a small, oval dark red berry (7-11 mm diameter), but they are structurally a pome (Latin word for fruit) containing a single seed surrounded by flesh
Birds eat the haws and disperse the seeds in their droppings. The seeds are also dispersed by soil and water movement.



Upper surface of the leaf

Underside of a leaf