Sorbus aucuparia L.

Abstract

Slender tree up to 15(-20) m with narrow crown and usually erecto-patent branches; bark greyish and smooth (Hedlund 1901; Hegi Fl. 4, ed. 2; Fl. Eur. 2; Fl. Br. Isl.; Rameau et al. 1989; Guendels 1990). Twigs pubescent when young, then glabrous and greyish-brown. Buds 10-15 mm, ovoid or ovoidconic, dark brown, somewhat pubescent (Fl. Br. Isl.; Rameau et al. 1989). Leaves 10-25 cm, pinnate, with (4-)5-7(-9) pairs of leaflets (Hedlund 1901; Hegi Fl. 4, ed. 2; Fl. Eur. 2; Fl. Br. Isl.). Leaflets 2.56(-9) cm, oblong, acute or subacute, more or less rounded at the often somewhat unequal base, serrate, sometimes doubly so, dark green and glabrous above; subglaucous beneath and pubescent at first, especially on the midrib, usually becoming subglabrous (Hegi Fl. 4, ed. 2; Fl. Br. Isl.). Terminal leaflet more or less equalling the lateral (never larger) (Fl. Br. Isl.). Petiole 2-4mm (Fl. Br. Isl.). Adaxial glands present on rachis (Robertson et al. 1992). Inflorescence a compound corymb, dense, manyflowered (usually about 250 flowers), woolly pubescent in flower (Hedlund 1901; Hegi Fl. 4, ed. 2; Fl. Br. Isl.). Flowers 8-10 mm diameter (Hedlund 1901; Fl. Eur. 2), generally 5-merous. Some rare 4-merous flowers were observed (Raspe 1998). Receptacle tomentose at first, turning glabrous after blooming (Kovanda 1961). Petals 3.5 mm, white, circular to oval, with short claws (Fl. Br. Isl.; Kovanda 1961). Sepals 1.5-1.8 mm, deltate, sometimes rounded (Hegi Fl. 4, ed. 2), finely and irregularly toothed, glandular (Kovanda 1961). Stamens as long as the petals (Hegi Fl. 4, ed. 2). The mean number of the cream anthers reaches 16 (4-merous flowers) to 25, generally 20 (Raspe 1998). There are (2-)3-4(-5) styles, free or connate at the base and pubescent on the basal part (Hegi Fl. 4, ed. 2; Fl. Br. Isl.; Raspe 1998). Carpels partly free or connate; two collateral, anatropic ovules per carpel (Kovanda 1961; Sterling 1965, 1969). Ovules have two integuments and an obturator (Kovanda 1961). Carpels fused with receptacle only up to two-thirds (Kovanda 1961). The part of the hypanthium between stamen insertion and the base of the styles is nectariferous (Raspe 1998). The nectar is fructose-glucose dominant (Percival 1961). Fruit a twoto five-celled, berry-like pome, each cell containing one or two small, brown seeds (Anonymous 1963). Fruit subglobose, depressed-globose, or ovoid, with few or no stone-cells and few inconspicuous lenticels (Fl. Eur. 2; Fl. Br. Isl.; Hegi Fl.4, ed.2; Grime et al. 1988; Snow & Snow 1988; Rameau et al. 1989; Stace 1997). Pome diameter 69(-14) mm (Hegi Fl. 4, ed. 2; Fl. Br. Isl.) or 8-9 x 10-11 mm (Hedlund 1901; Anonymous 1963; Herrera 1987; Grime et al. 1988). For fruit and seed mass see VIII(c). A cross section of the fruit shows a star-shaped central cavity, i.e. the walls of the ovary cells are split (Kovanda 1961). Fruit colour varies from scarlet to orange in the wild (Kovanda 1961), but cv. 'Fructu Luteo' produces golden fruits (McAllister 1996). Sorbuts aucuparia as well as S. torminalis (L.) Crantz, S. chamiiaemnespilus (L.) Crantz and S. ariia (L.) Crantz and their products form a hybrid complex (Proctor et al. 1989; Proctor & Groenhof 1992; Mikolas 1995; see below). Five subspecies are distinguished in Europe, described below. Ssp. auicuipar-ia: the buds, undersides of leaves and inflorescence-axis are more or less hairy. The petiole is usually more than 2.5 cm. The leaflets are firm, subobtuse or abruptly narrowed to an acute apex. Sepals are deltate and hairy. Fruit is subglobose. It occurs throughout most of the range of the species but it is rarer in the South (Fl. Eur. 2). Ssp. glabr-ata (Wimmer & Grab.) Cajander: is less hairy than ssp. aicucparia. The petiole is usually more than 2.5 cm. The leaflets are thin, gradually tapered to an acute apex, subglabrous or sparsely hairy on both surfaces. The inflorescence-axis is glabrous or nearly so. The sepals are rounded and hairy. Fruit is longer than wide. It occurs in northern Europe and in the mountains of central Europe (Fl. Eur. 2). Ssp. fenenskiania Georgiev & Stoj.: has leaflets up to 9 x 1-1.8 cm. They are linear-lanceolate, thin, *Abbreviated references are used for standard works, see Joutiirnal of Ecology (1975), 63, 335-344. Nomeniclature of vascular plants follows Floira Europoiea and Stace (1997) for British species.