5. [Alnus oblongifolia] Torr. Alder.
Alnus acuminata Sarg., not H. B. K.
Leaves oblong-lanceolate, acute; or rarely obovate and rounded at apex, gradually narrowed and cuneate at base, sharply and usually doubly serrate, more or less thickly covered, especially early in the season, with black glands, dark yellow-green and glabrous or slightly puberulous above, pale and glabrous or puberulous below, especially along the slender yellow midrib and veins, with small tufts of rusty hairs in the axils of the primary veins, 2′—3′ long, about 1½′ wide; petioles slender, grooved, pubescent, ¾′ long; stipules ovate-lanceolate, brown and scarious, about ¼′ in length. Flowers: staminate aments in short stout-stemmed racemes, during the winter light yellow, ½′—¾′ long and about 1/16′ thick, becoming when the flowers open at the end of February before the appearance of the leaves 2′—2½′ in length, with ovate pointed dark orange-brown scales; calyx 4-lobed; stamens 3 or occasionally 2, with pale red anthers soon becoming light yellow; pistillate aments naked during the winter, ⅛′ to nearly ¼′ long, with light brown ovate rounded scales; stigmas bright red. Fruit: strobiles ½′—1′ long, with thin scales slightly thickened and nearly truncate at apex; nut broadly ovoid, with a narrow membranaceous border.
A tree, in the United States rarely more than 20°—30° high, with a trunk sometimes 8′ in diameter, long slender spreading branches forming an open round-topped head, and slender branchlets slightly puberulous when they first appear, light orange-red and lustrous during their first winter, and marked by small conspicuous pale lenticels, becoming in their second year dark red-brown or gray tinged with red and much roughened by the elevated leaf-scars. Winter-buds acute, red, lustrous, glabrous, ½′ long. Bark thin, smooth, light brown tinged with red.
Distribution. Banks of streams in cañons of the mountains of southern New Mexico and Arizona at altitudes of 4000°—6000° above the sea; in Oak Creek Cañon near Flagstaff, northern Arizona (tree 100° × 3°, P. Lowell); and on the mountains of northern Mexico.
6. [Alnus maritima] Nutt. Alder.
Leaves oblong-ovate, or obovate, acute, acuminate or rounded at apex, gradually narrowed and cuneate at base, remotely serrate with minute incurved glandular teeth, and somewhat thickened on the slightly undulate margins, when they unfold, light green tinged with red, hairy on the midrib, veins, and petioles, and coated above with pale scurfy pubescence, at maturity dark green, very lustrous, and covered below by minute pale glandular dots, 3′—4′ long, 1½′—2′ wide, with a stout yellow midrib and primary veins prominent and glandular on the upper side and slightly puberulous below; petioles stout, yellow, glandular, flattened and grooved on the upper side, ½′—¾′ in length; stipules oblong, acute, about ⅛′ long, dark reddish brown, caducous. Flowers opening in the autumn: aments appearing in July on branches of the year and fully grown in August or early in September; staminate in short scurfy-pubescent glandular-pitted racemes on slender peduncles sometimes 1′ in length from the axils of upper leaves, covered at first with ovate acute dark green very lustrous scales slightly ciliate on the margins and furnished at apex with minute red points, at maturity 1½′—2½′ long, ¼′ to nearly ½′ thick, with dark orange-brown scales raised on slender stalks, and 4 bright orange-colored stamens; pistillate usually solitary from the axils of the lower leaves on stout pubescent peduncles, bright red at apex and light green below before opening, with ovate acute scales slightly ciliate on the margins, about ⅛′ long when the styles protrude from between the scales, beginning to enlarge the following spring. Fruit attaining full size at midsummer and then raised on a stout peduncle, broadly ovoid, rounded and depressed at base, gradually narrowed to the rather obtuse apex, about ⅝′ long and ½′ broad, with thin lustrous scales slightly thickened and crenately lobed at apex, turning dark reddish brown or nearly black and opening late in the autumn and remaining on the branches until after the flowers open the following year; nut oblong-obovoid, gradually narrowed and apiculate at apex, with a thin membranaceous border.
A tree, occasionally 30° high, with a tall straight trunk 4′—5′ in diameter, small spreading branches forming a narrow round-topped head, slender slightly zigzag branchlets, light green and hairy at first, pale yellow-green, very lustrous, slightly puberulous, marked with occasional small orange-colored lenticels, and glandular with minute dark glandular dots during their first summer, becoming dull light orange or reddish brown in the winter, and ashy gray often slightly tinged with red the following season; more often shrubby, with numerous slender spreading stems 15°—20° tall. Winter-buds acute, dark red, coated with pale lustrous scurfy pubescence, about ¼′ long. Bark ⅛′ thick, smooth, light brown or brown tinged with gray. Wood light, soft, close-grained, light brown, with thick hardly distinguishable sapwood.