86 
BETULA . 
Of the above plants the first two agree with the description of B. alpestris var. communis Regel in DC. Prodr. xvi, pt. ii, 173 
(1868), and the third with B. alpestris var. typica Regel op. cit ., p. 172. In cultivation, the Aberdeenshire plant approaches 
B. pubescens in its vegetative characters : it has not yet flowered. 
Iceland, Scandinavia, northern and central Russia, Greenland. 
Series ii. IVanae 
Nanae Regel in DC. Prodr. xvi, pt. ii, 162 et 171 (1868); Winkler in Pflanzenr. iv, pt. 61, 69 (1904); 
Ascherson und Graebner Syn. iv, 404 (191 1) ; Humiles Koehne Deutsche Dendrol. 107 (1893); Prantl in 
Pfianzenfam. iii, pt. i, 45 (1894). 
For characters, see page 80. 
3. BETULA NANA. Dwarf Birch. Plates 88; 87 
Betula nana L. Sp. Pl. 983 (1753); Lightfoot FI. Scot. 575 (1777); Syme Eng. Bot. viii, 187 (1868); 
Rouy FI. France xii, 255 (1910); Ascherson und Graebner Syn. iv, 406 (1911); B. nana var. europaea Ledebour 
FI. Ross, iii, 654 (1849). 
leones: — Smith Eng. Bot. t. 2326; Reichenbach Icon, xii, t. 621, fig. 1278; Hartig Forst. Culturpfl. t. 31. 
Camb. Brit. FI. ii. Plate 88 . (a) Fertile and barren shoots in summer. Forfarshire (E. S. M.). (b) Fruiting 
bracts (one enlarged). ( c ) Winged achenes (one enlarged), (b) and (c) drawn from dried specimens, 
Exsiccata : — Fries, ii, 55; Reichenbach, 1634; Schultz, x, 943; Tausch. 
Undershrub, either prostrate and attaining a length of about 1-5 m. or erect and nearly a 
metre high. Trunk in old plants sometimes attaining a thickness 
of 5 cm., often misshapen owing to the browsing of animals. Bark 
dull brown. Branches rigid, ascending, eglandular, internodes short 
especially towards the end. Young branches pubescent. Petioles 
very short. Laminae subrotund (about 1 — 2 cm. long), the lower 
ones often broader than long, strongly crenate, subcoriaceous, shining 
and dark green above, glabrous at maturity, strongly reticulated. 
Catkins small, sessile or subsessile ; May. Staminate catkins about 
8 mm. long. Bracts with peltate heads paler at the margin, ciliate. 
Pistillate catkins about 10 mm. long and 5 broad. Stigmas about 
as long as the ovary. Fruiting bracts small (about 2 mm. broad), 
cuneate below ; lateral lobes long, narrow, suberect. Wing of 
achene variable in breadth, often rudimentary. 
Peat moors, where the peat is very acidic, sometimes among 
Calluna vulgaris , sometimes on denuding peat ; from Argyllshire to 
Perthshire and Sutherland ; from 250 to 823 metres. Records from 
southern Scotland and northern England are all doubtful. 
Iceland, Scandinavia, Germany, eastern France, central Europe 
(ascending to 1980m.), Russia; northern Asia; North America, 
Greenland. 
B. nana y. pubescens (page 85). 
Map 1 1. Betula nana occurs in the 
counties which are shaded ; and there are 
more or less doubtful records of it for the 
counties marked “?” 
Genus 2. Alnus. 
Alnus [Tournefort Inst. 587, t. 359 (1719)] Miller Abridg. Gard. Diet. ed. 6 (1771); Gaertner De Fruct. ii, 
54, t. 90, fig. 2 (1791); Engler in Pfianzenfam. iii, pt. i, 45 (1894). 
Trees or shrubs. Catkins flowering before the leaves appear. Staminate catkins pendulous, 
with 3-flowered cymes. Perianth 4-partite, larger than in Bettila. Stamens 4. Pistillate catkins 
stout, ovoid or elliptical, with 2-flowered cymes. Perianth absent. Ovary 2-locular, 1 -seeded. 
Fruiting catkins very stout, persisting on the tree long after the seeds have been shed. Scales 
5-lobed. 
About 17 species; Europe, central and northern Asia, northern Africa, North and South 
America. 
The only British species, A. glutinosa , belongs to the section Gymnothyrsus Spach in Ann. Sc. Nat. ser. 2, xv, 204 (1841). 
