BETULA 
81 
Series i. A LBAE 
Albae Regel in DC. Prodr. xvi, pt. ii, 162 (1868); Ascherson und Graebner Syn. iv, 390 (1910). 
For characters, see page 80. 
British species and hybrid of Albae 
1. Betula alba (see below). Young branches and branches of the sucker-shoots with resinous, 
peltate glands, hairs absent. Laminae acuminate, doubly serrate. Lateral lobes of bracts more 
or less falcate. 
B. alba x -pubescetts (p. 82). Young branches usually with small resinous glands and hairs. Laminae 
and lateral lobes of bracts intermediate in shape. 
2. B. pubescens (p. 82). Young branches and branches of the sucker-shoots with hairs, 
resinous glands absent or more or less rudimentary. Laminae not acuminate (except in var. 
sudetica ), irregularly serrate. Lateral lobes of bracts spreading to erect. 
I. BETULA ALBA. White Birch. Plates 82, 83 ; 84 
Betula alba L. Sp. PL 982 (1753) partim; Roth Tent. FI. Germ, i, 404 (1788) partim ; Willdenow Sp. 
PI. iv, 462 (1805); Koch Syn. 662 (1837); Fries Ft. Suec. Mant. ii, 60 (1839); Babington Man. 282 (1843); 
B. verrucosa Ehrhart Beitr. vi, 98 (1791); Ascherson und Graebner Syn. iv, 391 (1910); Rouy FI. France xii, 
254 (1910); B. alba var. communis Hartman Skand. FI. 341 (1820); B. alba var. vulgaris Spach in Ann. Sc. Nat. 
ser. 2, xv, 186 (1841); B. alba subsp. verrucosa Syme Eng. Bot. viii, 182 (1868); B. alba subsp. verrucosa var. 
vulgaris Regel in DC. Prodr. xvi, pt. ii, 163 (1868); B. verrucosa var. vulgaris Winkler in Engler Pflanzenr. iv, 
pt. 61, 75 (1904)- 
leones: — Reichenbach Icon. t. 626, fig. 1288, as B. odorata\ FI. Dan. t. 2549, as B. verrucosa ; Syme Eng. 
Bot. viii, t. 1295, as B. verrucosa. 
Camb. Brit. FI. ii. Plate 82. (a) Branch of sucker in spring, (b) Branch of sucker in autumn, (c) Leaf 
(lower surface). Huntingdonshire (E. W. H.). Plate 8j. (a) Shoot with staminate catkins. ( b ) Shoot with 
pistillate catkin. ( c ) Fertile shoot in autumn, (d) Fruiting bracts (one enlarged), (e) Winged achenes (one 
enlarged). Huntingdonshire (E. W. H.). 
Exsiccata : — Billot, 463 ; Fries, ii, 53 ; Schultz, 520 bis ; Herb. FI. Ingric. viii, 582 c, as B. alba var. verrucosa ; 
herb. Marshall, 3380. 
Tree, growing to a height of about 20 — 25 m. Bark flaky, usually whitish or pale brownish 
grey, often very rugged and black at the base of the trunk in old trees. Young branches of 
the normal twigs glabrous except for the presence of small peltate glands ; of the suckers, 
with numerous and large peltate glands. Petioles relatively longer than in B. pubescens. Laminae 
rhomboid-acuminate, acutely biserrate with the primary serrations acuminate, about 3 — 7 cm. long 
and 2 '5 — 3^5 broad, glandular, slightly hairy when young, ultimately free of hairs, thinner than 
in B. pubescens , with raised veins on the upper surface ; of the suckers, often much larger. 
Catkins on short (0^5 — ro cm.) peduncles; April and early May. Staminate catkins cylindrical, 
pendulous, about 3 — 6 cm. long and 6 — 8 mm. broad. Bracts with the peltate heads with pale 
margins, ciliate, more or less glandular. Pistillate catkins not lengthening much in fruit, stout at 
maturity when they are about 2 — 3 cm. long and 1 broad, pendulous or ascending. Stigmas purplish. 
Mature bracts with a prominent central lobe which gradually narrows to an obtuse apex ; lateral 
lobes smaller, spreading, more or less falcate and sometimes strongly so ; August and September. 
Wing of fruits twice or thrice the diameter of the nutlets. 
I do not hesitate to retain the Linnaean name B. alba for this species, as it is the member of the series Albae which 
answers best to the diagnosis (“foliis acuminatis”) given by Linnaeus in his Species Plantarum, p. 982 (1753). There can, 
however, be no doubt that Linnaeus, the early British botanists, and also the two brothers Bauhin regarded B. alba and B. 
pubescens as constituting a single species. 
(/ 3 ) forma pendula E. S. Marshall in Moss Camb. Brit. FI. ii, 81 ; B. pendula Roth FI. Germ, i, 405 
(1788) partim ; B. alba var. pendida Aiton Hort. Kew. iii, 336 (1789) partim. 
Differs only in its terminal branches becoming pendulous and drooping at maturity. 
Eastern and central Highlands, from Perthshire to Ross-shire, and doubtless elsewhere. Frequently planted, 
as it is a graceful and beautiful tree. 
Europe (inch Corsica) ; Asia. 
II 
M. II. 
