Sorbus intermedia

Taxobox
name = "Sorbus intermedia"


image_width = 240px
image_caption = Leaves
regnum = Plantae
divisio = Magnoliophyta
classis = Magnoliopsida
ordo = Rosales
familia = Rosaceae
subfamilia = Maloideae
genus = "Sorbus"
subgenus = "Aria"
species = "S. intermedia"
binomial = "Sorbus intermedia"
binomial_authority = (Ehrh.) Pers.

"Sorbus intermedia" (Swedish Whitebeam) is a species of whitebeam native to the Baltic Sea region in southern Scandinavia (southern Sweden, easternmost Denmark (Bornholm) and the far southwest of Finland), the Baltic States, and northern Poland.Rushforth, K. (1999). "Trees of Britain and Europe". Collins ISBN 0-00-220013-9.] Den Virtuella Floran: [http://linnaeus.nrm.se/flora/di/rosa/sorbu/sorbint.html "Sorbus intermedia" (in Swedish; with maps)] ]

It is a medium-sized deciduous tree growing to 10–20 m tall with a stout trunk up to 60 cm diameter and grey bark; the crown is dome-shaped, with stout horizontal branches. The leaves are green above, and densely hairy with pale grey-white hairs beneath, 7–12 cm long and 5–7 cm broad, with four to seven oval lobes on each side of the leaf, broadest near the middle, rounded at the apex, and finely serrated margins. The autumn colour is dull yellowish to grey-brown. The flowers are 15–20 mm diameter, with five white petals and 20 yellowish-white stamens; they are produced in corymbs 8–12 cm diameter in late spring. The fruit is an oval pome 15 mm long and 10 mm diameter, orange-red to red, maturing in mid autumn. The fruit is dryish, and eaten by thrushes and waxwings, which disperse the seeds.Mitchell, A. F. (1974). "A Field Guide to the Trees of Britain and Northern Europe". Collins ISBN 0-00-212035-6.]

It is closely related to "Sorbus hybrida" (Finnish Whitebeam), which differs in having the leaves more deeply lobed, with the basal two pairs cut right to the midrib as separate leaflets. Both are tetraploid apomictic species which breed true without pollination, and ultimately of hybrid origin between "Sorbus aria" and "Sorbus aucuparia" or possibly "Sorbus torminalis".Bean, W. J. (1980). "Trees and Shrubs Hardy in the British Isles" 8th ed., vol. 4. John Murray ISBN 0-7195-2428-8.]

Cultivation and uses

It is widely grown as an ornamental tree in northern Europe, valued for its tolerance of urban street conditions; it is very commonly used in avenues and urban parks. It is frequently naturalised in the British Isles.Flora of NW Europe: [http://ip30.eti.uva.nl/BIS/flora.php?selected=beschrijving&menuentry=soorten&id=2743 "Sorbus intermedia"] ] In recent years, much new planting of "Swedish Whitebeam" has actually been of the related "Sorbus mougeotii" (Vosges Whitebeam), another apomictic species from further south in Europe that has more erect branching, less deeply lobed leaves with whiter undersides to the leaves, and darker red fruit.Hansen, K. F. (1985). Bornholmsk røn, Seljerøn, vogeserrøn. "Haven" 85 (7/8): 421-423 (in Danish).]

References