Horticulture/Cornus kousa

The Kousa Dogwood (Cornus kousa or Benthamidia kousa), also known as the Japanese Flowering Dogwood (Yamaboushi ヤマボウシ in Japanese), is a small flowering tree native to Eastern Asia and Japan, but grown in other regions as an ornamental and occasionally for its edible fruit.

Description
It is a small deciduous tree 8–12 m tall, native to eastern Asia. Like most dogwoods, it has opposite, simple, ovate leaves, which are 4–10 cm long. Fall colors are vivid reds, yellows, and purples.

The tree is showy when in flower, but the "showy" elements are actually white bracts which are held below dense cymes of yellow-green flowers. The flowering is in spring, shortly after it leafs out. It has a relatively upright habit, unlike the closely related Flowering Dogwood (../Cornus florida/) of eastern North America, which has a sprawling habit. It also differs from that in flowering about a month later, and in having pointed (not rounded) flower bracts.

The fruit is a globose pink to red amalgamate of drupes containing several 1-2 seeded stones, 2–3 cm diameter, and resembling a pom-pom. The berries can grow even larger towards the end of the season and some berries that do not fall from the tree surpass 4 cm. It is edible, though the tree is not commonly grown for fruit.

The bark exfoliates in irregular patches or gray, brown, tan, and olive-green, providing winter interest. The stems are horizontally arranged, slender, and rigid. Buds are valvate, the flower buds longer and larger than the vegetative buds.

Growing conditions
Does best in moist, well-drained, fertile soils, but is adabtable. Full sun to dense shade, flowering better in more sun.

Natural Varieties

 * Cornus kousa var. kousa. Leaves 4–7 cm; flower bracts 3–5 cm.Native to Japan.
 * Cornus kousa var. chinensis. Leaves 5–10 cm; flower bracts 4–6 cm, opening white and then fading to pink. Native to China.

Cultivars

 * ‘China Girl’: Heavy flowering, flowers when very young.
 * ‘Elizabeth Lustgarten’: selection of var. chinensis with weeping branchlets.
 * ‘Gold Star’: Bracts white, fading to pink. Leaves with dark yellow centers, red with purple margins in fall color. Shrubby form.
 * ‘Milky Way’: heavy flowering and fruiting.
 * ‘Rubra’: flower bracts pink.
 * ‘Satomi’: Floral bracts dark pink, fall color purple.
 * ‘Snowboy’: Dwarf (to 2.5 m), leaves grayish, with white margins.
 * ‘Summer Stars’: Heavy flowering, fall color maroon.
 * ‘Variegata’: leaves variegated with white.
 * ‘Xanthocarpa’: Fruits yellow.

Uses
==Maintenance=

Pests and diseases
It is resistant to the dogwood anthracnose disease, caused by the fungus Discula destructiva, unlike Flowering Dogwood, which is very susceptible and commonly killed by it; for this reason, Kousa Dogwood is being widely planted as an ornamental tree in areas affected by the disease. A number of hybrids between Kousa Dogwood and Flowering Dogwood have also been selected for their disease resistance and good flower appearance.

See ../Cornus/ for a list of pests and diseases affecting the genus.