Betula Betula, Roth

1. B. pendula Roth View in CoL , Tent. FI. Germ. 1: 405 (1788)

(R. alba sensu Coste , B. verrucosa Ehrh. ).

Tree up to 30 m; bark smooth and silvery-white except towards the base, where it is usually dark and more or less dissected into rectangular bosses. Young twigs glabrous, with numerous appressed, peltate resin-glands; twigs usually very slender and pendent. Leaves 2-7 cm, ovate-deltate, acuminate, sharply biserrate with prominent primary teeth, subglabrous when mature, thin. Male catkins 3-6 cm. Fruiting catkin 1 - 5-3- 5 x 1 cm; scales with cuneate base, and with wide, more or less recurved, lateral lobes and a deltate, obtuse median lobe. Wing of fruit 2-3 times as wide as the narrowly ovoid glabrous nutlet. 2« = 28. Forming woods, particularly on light sandy soils, often secondary after forest destruction. Throughout most ofEurope, from 69° N. in Norway to Sicilia; local in the south and confined to mountains. All except Az BI Cr Fa Gr Is Sa Sb Tu; not native in Lu but planted.

Rather variable, especially in leaf-shape and habit. Lindquist (Svensk Bot. Tidskr. 41: 62 (1947)) distinguishes from the typical plant a northern var. lapponica with smooth bark (even in old trees), less pendent twigs and somewhat larger scales and fruits. It may merit subspecific distinction.

B. oycoviensis Besser, Prim. FI. Galic. 2: 289 (1809), described from S.E. Poland, resembles 1 and has the same chromosome number, but is of shrubby habit, has 3-4 (not about 2) leaves on the flowering twigs, and leaves with almost equal teeth. Other shrubby variants have been described from Scandinavia and elsewhere; some at least seem to be of hybrid origin (see 2).