95 6 The Trees of Great Britain and Ireland 



ALNUS RUBRA, Oregon Alder 



Alnus rubra, Bongaxd, Mem. Acad. Sf. Pktersb. ii. 162 (1833); Winkler, Betulacea, 124 (1904); 



Sargent, Bot. Gazette, xliv. 226 (1907.) 

 Alnus oregona, Nuttall, Sylva, i. 28, t. 9 (1842); Sargent, Silva JV. Amer. ix. 73, t. 454 (1896), and 



Trees M. Amer. 210 (1905). 

 Alnus incana, Moench, var. rubra, Kegel, Mem. Soc. Nat. Mosc. xiii. 157 (1861). 



A tree attaining 80 feet in height and 10 feet in girth. Bark greyish or 

 whitish, thin, roughened by minute wart -like excrescences. Young branchlets 

 glabrous, three-angled at the tip, scarcely viscid except at the beginning of the 

 season. Leaves (Plate 268, Fig. 16) about 4 or 5 inches long and 2^ inches wide, 

 ovate or elliptical, rounded or cuneate at the base, acute at the apex ; nerves, about 

 15 pairs, each running straight and parallel to the apex of a lobule, which is 

 furnished with minute gland-tipped serrations ; margin slightly revolute and ciliate ; 

 upper surface dark green, slightly pubescent ; lower surface whitish or greyish, 

 covered with a minute brown pubescence ; petiole, \ inch, with a few scattered 

 hairs. Buds beaked at the apex, glabrous, stalked. Stipules ovate, acute, tomentose, 

 ^ to J- inch long. 



Flowers opening in spring before the leaves. Staminate catkins, three to six in 

 a raceme, 4 to 6 inches long when fully opened. Cones, three to six in a raceme, 

 |- to I inch long, with truncate scales, much thickened at the apex ; nutlet orbicular 

 or obovate, surrounded by a membranous wing. 



This species can only be confused with A. incana, from which it differs in the 

 glabrous branchlets and the usually larger leaves with revolute margins. The buds 

 also differ, those of A. rubra being elongated, pointed, and glabrous, whilst those of 

 A. incana are shorter, rounded at the apex, and pubescent. 



Alnus rubra, according to Sargent, ranges from Sitka, where it often 

 clothes mountain -sides to elevations of 3000 feet above the sea, southwards 

 through the islands and coast ranges of British Columbia, and through western 

 Washington and Oregon, and the canons of the Californian coast ranges, to 

 the Santa Inez mountains near Santa Barbara. It grows to its largest size in the 

 neighbourhood of Puget Sound, where it commonly fringes the banks of streams and 

 grows in wet places.-' 



This species was introduced into cultivation a few years ago, and there are two 

 trees in Kew Gardens about 15 feet in height. Elwes has raised seedlings from 

 these trees, which grow very rapidly in heavy soil at Colesborne, but being planted 

 in a situation very subject to late frosts, have suffered on several occasions, when 

 the grey and common alders standing near were quite untouched. 



The wood is light, soft, brittle, and not strong, but close-grained and takes 

 a fine polish ; and is now largely used in Washington and Oregon for making 

 furniture. (A. H.) 



1 In Vancouver Island, the stem and branches are often covered with Polypodium falcatum, the creeping rhizomes of 

 which find anchorage in its moss-covered bark. Cf. Postehia, 1906, p. 76. A figure of the tree, growing in a moist part of 

 the forest and surrounded by devil's club (Echinopanax horridum), is given in Piper, Flora of the State of Washington, 

 plate vii. (1906). 



