Cornus (Cornel, Dogwood)is a genus of flowering plants in the family Cornaceae, comprising about 30-50 species, native to temperate and boreal Eurasia and North America, Japan and China and the southeastern United States.
Cornus drummondii (Roughleaf Dogwood) is a small deciduous tree native to the Great Plains and Midwestern regions of United States, found around the Mississippi river. It is mostly found around forest borders. It can grow to 4-8 m tall and 3-5 m wide, bearing four-petaled off white flowers in summer, follow by small, round fruit that ripen from august to October. The species can form a dense thicket that is used as a hedge, border or cover for wildlife. There are about 40 species of birds feeding on the fruits of the Roughleaf Dogwood.
Cornus canadensis (Canadian Dwarf Cornel, Canadian Bunchberry, Crackerberry), 20-30 cm tall, is native to Northern China, Japan, far-eastern Russia and North America. The species needs cool moist soils, and is found growing along the margins of moist woods, on old tree stumps, in mossy areas and other open and moist habitats. It is a slow-growing herbaceous subshrub bearing tiny flowers that form an inflorescence at the center of four white, petal-like bracts 3-4 in diameter. The fruits are edible and birds are the main dispersal agents of the seeds, feeding on the fruits during their fall migration. It is also an important forage plants in Alaska, providing food for mule deer, black-tailed deer and moose during growing season.
Cornus florida (Flowering Dogwood) is native to eastern North America. It is a small deciduous tree growing to about 10 m tall. the leaves are simple, oval with acute tip, 6-13 cm long and 4-6 cm wide, with an entire margin. The leaves turn into rich red brown in autumn. The bisexual flowers of about 20 are produced in a dense, rounded, umbel-shaped inflorescence, 1-2 cm in diameter. Each flower is small and inconspicuous, with four greenish-yellow petals 4 mm long. The flower head is surrounded by four large white, pink or red 'petals' (actually bracts), with a distinct notch at the apex. The fruit is a cluster of two to ten drupes, ripening in late summer to early autumn, to a bright red, or occasionally yellow with a rosy blush. The fruits are an important food source for dozens of species of birds, which help in dispersing the seeds.
Cornus mas (European Cornel) is a species native to southern Europe and southwest Asia. It is known as Cornelian Cherry in North America. It is a medium to large deciduous shrub or small tree growing to 5-12 m tall. It has dark brown branches and greenish twigs. The leaves are opposite, with an ovate to oblong shape and an entire margin. The small, four yellow-petaled flowers are produced in clusters of 10-25 together in the late winter, well before the leaves appear. The fruit is an oblong red drupe, 2 cm long and 1.5 cm in diameter, containing a single seed. the fruit is edible, but the unripe fruit is astringent. The fruit is dark ruby red when ripen in mid to late summer, and it is fully ripen after it falls from the tree. The species is also grown as ornamental plant for its late winter flowers.
Cornus sericea (Red Osier Dogwood, Redtwig Dogwood, Red-rood) is a species native throughout the northern and western North America, growing in areas of damp soil, such as wetlands. It is a medium to tall deciduous shrub growing to 1.5-4 m tall and 3-5 m wide, spreading vigorously by underground stolons to form a dense thickets. The branches and twigs are dark red, and the leaves are opposite, with an ovate to oblong shape and an entire margin. The leaves are dark green above and glaucous below, and turn to bright red to purple in autumn. The small, dull white flowers are produced in cluster of 3-6 cm in diameter, follow by globose white berries of 5-9 mm in diameter. This species is a popular ornamental shrub that is often grown for its red twigs.
Different species of Cornus has different growing requirement. Propagation is by greenwood cuttings in summer; hardwood cuttings in autumn; or graft in winter. It is a largely trouble-free plant but beware of attack by anthracnose or canker.
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