Hedlundia hybrida (formerly Sorbus hybrida), the Swedish service-tree[2]Finnish whitebeam, or oakleaf mountain ash,[3] is a species of
whitebeam[1] native to Norway, eastern Sweden, south-western Finland, and locally in Latvia.[4][5][6]
Description
Leaf; under side (left) and upper side (right)
Hedlundia hybrida is a medium-sized
deciduoustree growing to 10–15 m (33–49 ft) tall with a stout trunk up to 60 cm (24 in) in diameter, and grey
bark. The crown is columnar or conic in young trees, becoming rounded with age, with branches angled upwards. The
leaves are green above, and densely hairy with white hairs beneath. 7–12 cm (2.8–4.7 in) long and 5–8 cm (2.0–3.1 in) broad, the leaves are lobed, with six to nine oval lobes on each side of the leaf. These lobes are broadest near the base with the two basal pairs of lobes cut right to the midrib as separate leaflets, rounded at the apex, with finely serrated margins. The autumn colour is dull rusty brown. The
flowers are 20 mm (0.79 in) in diameter, with five white petals and 20 yellowish-white stamens; they are produced in
corymbs 6–11 cm (2.4–4.3 in) in diameter in late spring. The
fruit is a globose
pome 7–12 mm (0.28–0.47 in) in diameter, bright red, maturing in mid-autumn. The fruit is succulent, and eaten by
thrushes and
waxwings, which disperse the
seeds.[4][6]
Taxonomy
It is a
tetraploid species of
hybrid origin between the
European rowan (Sorbus aucuparia) and the
Swedish whitebeam (Scandosorbus intermedia),[5] the latter being a tetraploid triple hybrid between S. aucuparia, the
wild service tree (Torminalis glaberrima), and the
common whitebeam(Aria edulis) or one of its close relatives.[7][8]S. intermedia differs from H. hybrida in having the leaves less deeply lobed with no separate leaflets. Closely related Hedlundia meinichii is a triploid or tetraploid species of hybrid origin between H. hybrida and S. aucuparia[9][10] and differs in having the basal four to six pairs of lobes cut right to the midrib as separate leaflets. All three polyploid species are
apomictic species which breed true without pollination.[4]
^USDA, NRCS (n.d.).
"Sorbus hybrida". The PLANTS Database (plants.usda.gov). Greensboro, North Carolina: National Plant Data Team. Retrieved 24 November 2015.
^
abVedel, H., & Lange, J. (1960). Trees and Bushes in Wood and Hedgerow. Metheun & Co. Ltd., London.
^Nelson-Jones, E.B.; Briggs, D.; Smith, A.G. (2002). "The origin of intermediate species of the genus Sorbus". Theoretical and Applied Genetics. 105 (6–7): 953–963.
doi:
10.1007/s00122-002-0957-6.
PMID12582921.
S2CID21448997.
^Bolstad, A. & Salvesen, P. (1999). "Biosystematic studies of Sorbus meinichii (Rosaceae) at Moster, S. Norway". Nordic Journal of Botany. 19 (5): 547–559.
doi:
10.1111/j.1756-1051.1999.tb01138.x.
^Liljefors, A. (1953). "Studies on propagation, embryology, and pollination in Sorbus". Acta Horti Bergiani. 16: 277–329.