Sorbus L.

28. Sorbus L. View in CoL 1

Deciduous trees or shrubs without spines. Leaves simple, lobed or pinnate. Flowers in compound corymbs. Petals white, rarely pink; stamens 15-25; carpels 2-5, partly free or connate, walls cartilaginous or membranous in fruit; ovules 2; styles free or connate at base.

The five most widespread European species (1, 2, 3, 4 and 5) are amphimictic, but some at least of the local species are polyploid and apomictic. Species 1 does not hybridize with the others in nature, but 2,3,4, 5 and their products form a hybrid complex. Some of the hybrid products are amphi- and some apomictic. It is likely that many of the apomictic species have arisen by hybridization, and their probable origin is given in the text. It is not practicable to describe all these species, partly because their taxonomy has not been elucidated for the whole of Europe. Accordingly, a number of representative species has been described (6 to 18), and after each of these have been listed the other species which seem to be most closely related to them. (This is analogous to the procedure in Rubus .)

Im portant characters used in the identification of the species are the depth and character of toothing and lobing of leaves of short shoots, and the colour of the fruit and the distribution of its lenticels. The leaves referred to in the descriptions are always those of the short shoots, unless otherwise specified.

A more detailed treatment is given in the monograph by T. Hedlund, Kungl. Svenska Vet.-Akad. Handl. nov. ser., 35(1): 1-147 (1901). Accounts for particular countries include: E. F. Warburg in Clapham, Tutin and Warburg, Flora o f the British Isles ed. 2,423-437. Cambridge. 1962. Z. Kârpâti, Feddes Repert. 62:71-331 (1960) and Bot. Közl. 52:135-140 (1966). R. Düll, Ber. Bayer. Bot. Ges. 34: 11-65 (1961). M. Kovanda, Acta Dendrol. Cech. 3: 23-70 (1961). There is an account of cytology and the breeding system in two papers by A. Liljefors, Acta Horti Berg. 16(10): 277-329 (1953) and 17: 47-113 (1955).

1 Leaves pinnate, with the terminal leaflet about the same size as the others 2 Bark shredding; styles 5; ripe fruit 20 mm or more, greenish or brownish 1. domestica 2 Bark smooth; styles 3-4; ripe fruit less than 14 mm, scarlet 2. aucuparia 1 Leaves simple, lobed, or pinnatifid, or, if pinnate, with the terminal leaflet much larger than the others 3 Leaves green beneath at maturity, more or less concolorous 4 Tree; leaves lobed; fruit brown 3. torminalis 4 Shrub; leaves not lobed; fruit scarlet 4. chamaemespilus 3 Leaves white- or grey-tomentose beneath at maturity 5 Leaves not or only very shallowly lobed 6 Leaves grey-tomentose beneath 7 Leaves not lobed, coarsely toothed 17. sudetica 7 Leaves very shallowly lobed, finely toothed 18. margittaiana 6 Leaves white-tomentose beneath 8 Leaves usually widest at or below middle, rounded at base; fruit usually longer than wide 5. aria 8 Leaves usually widest above middle, cuneate at base; fruit not longer than wide 9 Leaves with teeth symmetrical and patent; fruit usually less than 12 mm, with few lenticels 6. graeca 9 Leaves with teeth curved on outer edge; fruit usually more than 12 mm, with numerous lenticels 7. rupicola 5 Leaves distinctly lobed 10 Leaves white-tomentose beneath, usually with less than 7 pairs of lateral veins 8. umbellata 10 Leaves with whitish-, yellowish- or grey-green tomentum beneath, usually with more than 7 pairs of lateral veins 11 Leaves with at least 1 pair of free leaflets 12 Leaves with 2 pairs of free leaflets 13. hybrida 12 Leaves with 4-5 pairs of free leaflets 14. meinichii 11 Leaves (at least those of the short shoots) without free leaflets 13 Leaves deeply lobed, lobes extending to £ of the way to the midrib 12. dacica

13 Leaves less deeply lobed 14 Leaves usually less than 8 cm; fruit 6-8 mm 9. minima 14 Leaves usually more than 8 cm; fruit more than 8 mm

15 Leaf-lobes shallow, extending about f of way to midrib 16. latifolia

15 Leaf-lobes well-marked, extending of way to midrib

16 Leaves l£-2 times as long as wide; fruit with few,

small lenticels

17 Leaves with whitish-grey tomentum beneath; fruit

c. 10 mm, subglobose 10. mougeotii

17 Leaves with yellowish-grey tomentum beneath; fruit

12-15 mm, much longer than wide

15. intermedia

16 Leaves c. 1 | times as long as wide; fruit with many,

large lenticels

18 Fruit red 11. austriaca

18 Fruit yellowish-brown 16. latifolia