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Alnus 937
or rounded at the base, short- or long-acuminate, with slight axil-tufts beneath.
*** Leaves with serrate lobules.
11. Alnus glutinosa, Gertner. Europe, Siberia, Western Asia, North Africa. See below.
- Branchlets usually glabrous. Leaves obovate, cuneate at the base; obtuse, truncate or rounded at the apex ; with prominent axil-tufts beneath.
12. Alnus glutinosa, Gertner, var. darbata, Ledebour (Alnus barbata, C.A. Meyer). Caucasus. See p. 938.
- Branchlets pubescent. Leaves elliptical, rounded at the base and apex, covered on both surfaces with pubescence, densest on the midrib and nerves beneath.
13. Alnus tenutfolia, Nuttall. Western North America. See p. 957.
- Branchlets glabrous. Leaves ovate, broad and rounded at the base, acute or shortly acuminate at the apex, pubescent on the midrib beneath with inconspicuous axil-tufts.
14. Alnus subcordata, C. A. Meyer. Caucasus, North Persia. See p. 951.
- Branchlets pubescent. Leaves ovate-oblong, unequal and rounded or sub-cordate at the base, cuspidate-acuminate at the apex, pubescent on the midrib and nerves beneath.
ALNUS GLUTINOSA, Common Alder
- Alnus glutinosa, Gaertner, De Fruct. ii. 54 (1791); Loudon, Arb. et Frut. Brit. iii. 1678 (1838); Willkomm, Forstliche Flora, 339 (1887); Mathieu, Flore Forestière, 421 (1897); Winkler, Betulaceæ, 115 (1904).
- Alnus nigra, Gilibert, Exerc. ii. 401 (1792).
- Alnus communis, Desfontaines, Tabl. Hort. Paris, 213 (1804).
- Alnus vulgaris, Persoon, Syz. ii. 550 (1807).
- Betula Alnus glutinosa, Linnæus, Sp. Pl. 983 (1753).
- Betula Alnus, Scopoli, Fl. Carn. ii. 233 (1772).
- Betula glutinosa, Lamarck, Dict. i. 454 (1783).
- Betula palustris, Salisbury, Prod. 395 (1796).
A tree, occasionally attaining 100 feet in height and 12 feet or more in girth. Bark of young trees smooth and greenish ; after twenty years old becoming brownish- black and divided on the surface into broad flattened plates. Young branchlets, three-angled at the tip, usually glabrous, occasionally pubescent, covered with glands, which secrete a waxy resin, often seen on the dried twigs as a bluish bloom. Leaves (Plate 268, Fig. 6) averaging 33 inches long and 3 inches broad, variable in shape, but nearly always broadest above the middle, obovate, sub-orbicular or elliptical ; cuneate at the base; obtuse, truncate, or retuse at the apex; margin entire in the
basal third, elsewhere lobulate, each lobule serrate or dentate; upper surface dark green, shining, glabrous; lower surface light-green, pubescent along the midrib and