Sorbus scalaris
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Credits
Article from Bean's Trees and Shrubs Hardy in the British Isles
Recommended citation
'Sorbus scalaris' from the website Trees and Shrubs Online (treesandshrubsonline.
Genus
- Sorbus
- Subgen. Sorbus; Sect. Sorbus
Common Names
- Ladder Mountain Ash
- Ladder Rowan
Synonyms
- Pyrus scalaris (Koehne) Bean
- Sorbus pluripinnata (Schneid.) Koehne
- Sorbus foliolosa var. pluripinnata Schneid.
Other taxa in genus
- Sorbus americana
- Sorbus amoena
- Sorbus arachnoidea
- Sorbus aucuparia
- Sorbus carmesina
- Sorbus cashmiriana
- Sorbus commixta
- Sorbus coxii
- Sorbus decora
- Sorbus discolor
- Sorbus ellipsoidalis
- Sorbus esserteauiana
- Sorbus fansipanensis
- Sorbus foliolosa
- Sorbus forrestii
- Sorbus glabriuscula
- Sorbus glomerulata
- Sorbus gracilis
- Sorbus helenae
- Sorbus hupehensis
- Sorbus hypoglauca
- Sorbus insignis
- Sorbus 'Joseph Rock'
- Sorbus khumbuensis
- Sorbus koehneana
- Sorbus kongboensis
- Sorbus kurzii
- Sorbus lingshiensis
- Sorbus matsumurana
- Sorbus microphylla
- Sorbus muliensis
- Sorbus olivacea
- Sorbus parvifructa
- Sorbus pohuashanensis
- Sorbus poteriifolia
- Sorbus prattii
- Sorbus pseudohupehensis
- Sorbus pseudovilmorinii
- Sorbus randaiensis
- Sorbus reducta
- Sorbus rinzenii
- Sorbus rubescens
- Sorbus rufopilosa
- Sorbus rushforthii
- Sorbus sambucifolia
- Sorbus sargentiana
- Sorbus sitchensis
- Sorbus tianschanica
- Sorbus ursina
- Sorbus vilmorinii
- Sorbus wallichii
- Sorbus wilsoniana
Small spreading tree to 10 m. Twig grey. Bud ovoid, red, to 11 mm, covered with white hairs. Stipules large, leafy, persistent, especially in the inflorescence. Leaves 130—200 mm with 10–16 pairs of leaflets. Leaflets to 35—50 × 5—10 mm (rarely to 60 × 15mm), narrowly oblong, toothed for about 3/4 of their length on long shoots but only in the apical 1/4 on short shoots, apex acute to obtuse, base rounded, slightly asymmetric; blades coriaceous, glossy and with impressed veins above, densely white tomentose and papillose beneath. Inflorescence corymbose. Flowers white, to 8 mm across. Fruit bright red, more or less spherical, small, to 7 × 7.5 mm. Sepals fleshy, semicircular, obtuse. Carpels 3—4, semi-inferior, apices white hairy free within depression within calyx. Styles 1.75 mm, distantly inserted. Seed yellow-brown, about 2 × 1 mm, 2—3 per fruit. A relatively uniform sexual diploid (2n=34) species.
Distribution China W Sichuan
Habitat Sorbus scalaris is confined in the wild to an area south of Baoxian (Moupin) in western Sichuan, to the south of the area in which S. esserteauiana occurs – see comments under S. esserteauiana.
Sorbus scalaris makes an attractive small spreading tree with delicate foliage which usually turns a brilliant orange-red in the autumn and bears heavy crops of red fruit. It is available commercially from several sources so is sometimes seen as street tree, in private gardens as well as in arboreta. Of all the orange-red fruited species it is perhaps the most attractive small tree and could be more widely planted. Unfortunately most, if not all, of the older trees in cultivation are likely to be of the clone distributed by Hilliers. The several seedlings raised from a collection made on a recent expedition to Sichuan have provided new clones.
All but one seedling of a progeny raised from the single tree in the Hillier arboretum were hybrids, indicating that S. scalaris is largely self-incompatible.
BEAN:
A tree with a spreading crown, up to 35 ft high in the wild; young shoots coated at first with white or greyish hairs, becoming glabrous, dark grey in their second year; winter-buds ovoid, about 3⁄8 in. long, the outer scales glabrous, the inner white-hairy. Leaves up to 8 in. long including petiole, with ten to sixteen closely set pairs of leaflets; rachis deeply grooved, winged in the apical part of its length, at first rosy purple, later green tinged with red, grey-hairy. Lateral leaflets narrowly oblong, sharply or bluntly acute at the apex, 1⁄2 to 11⁄2 in. long, 1⁄4 to 3⁄8 in. wide, toothed in the upper half or one-third, sometimes almost entire, dark green and soon glabrous above, covered beneath with a whitish, cobwebby indumentum. Stipules large, toothed, up to 1⁄2 in. wide, present both on strong growths and under the inflorescence. Flowers dull white, opening in late May or early June, about 1⁄4 in. across, in clusters up to 7 in. wide, all the inflorescence branches grey-woolly. Anthers cream-coloured. Styles usually three. Fruits globose, about 1⁄4 in. wide, bright red, ripening in October, up to 200 or so in each cluster. Bot. Mag., n.s., t. 69.
Native of W. Szechwan, China; discovered and introduced by Wilson in 1904. It is a species of great character but not commonly met with outside collections. The fern-like foliage is brownish crimson or bronze when it expands in April and renders the tree unmistakable when mature, with its narrow, dark green, closely set leaflets. The autumn colour is unreliable but the leaves turn orange-yellow on some soils before falling late in the autumn. The fruits are borne on spurs all along the branches, and are usually among the last to be taken by birds. As usually seen, S. scalaris is a short-trunked tree with spreading branches. It received an Award of Merit in 1934.
From the Supplement (Vol. V)
specimens: Westonbirt, Glos., Gate, 30 × 21⁄2 (1983); Savill Garden, Windsor Great Park, 28 × 21⁄2 ft (1983); Bargany, Ayrs., 36 × 21⁄4 ft (1985).
