Plant of thr Month: November
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Sorbus hupehensis var. obtusa (syn. S. hupehensis 'Rosea')
Common name: Hubei rowan
Family: Rosaceae
Vital statistics
Height and spread: Broadly columnar, open, spreading tree up to 8m (26.5ft) high and wide.
Form: Deciduous tree.
Soil: Moderately fertile, humus-rich, moist but well-drained acid to neutral soil.
Aspect: Full sun or light dappled shade.
Hardiness: Fully hardy throughout the British Isles. |
There is a young plant of Sorbus hupehensis var. obtusa on the bank below the Plant Centre at Rosemoor and a rather more mature specimen in the Arboretum in Lady Anne's Garden.
Sorbus
The Sorbus genus covers about 190 different species of deciduous trees and shrubs, found mainly in northern temperate regions, in woodland, on hills, mountains and on scree.
Sorbus species and cultivars are prized for their ornamental qualities. Their leaves are decorative, and may be either simple or pinnate, and often colour well in autumn. Their flowers are a second plus point. They grow as terminal corymbs of small, white or rarely pink flowers in spring and early summer. These are followed by round or oval berries that may be white, yellow, orange, red or brown.
There are two basic types of Sorbus. The first belong to Section Aria and include the whitebeams. They have simple leaves that often have serrated margins and are sometimes lobed. The leaves are ordinarily white or silvery beneath giving them a shimmering look when blown by the breeze. In the autumn, their clusters of brown to red fruits are attractive and their foliage turns vivid colours. S. intermedia (Swedish whitebeam) is a small to medium-sized tree with a dense, rounded head of branches. The deeply lobed, shiny dark green leaves are clothed in white down on the underside. In the spring, compact heads of white flowers are produced; these are followed by bunches of reddish-orange berries. S. vestita (Himalayan whitebeam) is an attractive, medium-sized tree with large green leaves with a silvery-white or buff colour beneath. The green fruits are tinged and speckled with brown. S. alnifolia (Korean mountain ash) grows 12-15m (40-50 ft) high. Its crown is cone-shaped when young, eventually becoming rounded. In the spring, it bears white blossoms that are followed by clusters of bright orange to red berries.
The plants of the second type belong to Section Aucuparia and include mountain ashes. Sorbus hupehensis var. obtusa belongs in this Section. These plants have pinnate leaves, giving them a fern-like appearance; the foliage turns shades of red and yellow in autumn. In the spring, they produce clusters of cream-coloured flowers, which are followed by bunches of attractive berries that are usually brilliant red, but may be white, pink, orange, or yellow. S. koehneana is a small tree or medium-sized shrub. Its leaves consist of 17 to 33, slender, toothed leaflets. Its porcelain white fruits are produced in pendant bunches on red stalks.
Sorbus hupehensis var. obtusa
This tree has been selected for plant of the month for the fruit and colour it produces at this time of year. Its pinnate leaves, up to 15cm long, each with up to 15 ovate, blue-green leaflets turn a vivid scarlet red in autumn. In spring corymbs of white flowers are borne from which the spherical fruit form later, initially white before ripening to dark pink.
AGM
The RHS Floral Committee B awarded Sorbus hupehensis var. obtusa an Award of Garden Merit and described it as: Compact medium-sized deciduous tree with leaves composed of about 11 oblong, blunt, bluish-green leaflets. Creamy-white flowers followed by rosy-pink fruits.
Cultivation
Sorbus hupehensis var. obtusa grows best in moderately fertile, humus-rich soil that is moist but well drained and slightly acidic. It needs full sun but does not like intense heat and should be watered well and mulched during periods of dry weather. Pruning, if necessary, should be done in early spring or winter.
Sorbus hupehensis var. obtusa are tolerant of atmospheric pollution, and suitable as specimen trees in small gardens in the city. They are also ideal for wild or woodland gardens. The raw fruit should not be ingested as it may cause a mild stomach upset.
The genus is prone to canker and fireblight and is sometimes attacked by aphid and blister mite.
Propagation
Sow fresh seed in containers in a cold frame in autumn.
Take greenwood cuttings in early summer.
Bud in summer, graft in winter.