Betula. BETULACEJ2. 79 



Territory, but mostly without fruit. A single fruiting specimen from Sauvies Island, Willamette 

 Slough, Oregon {lluwcll), has a stout straight style and a retii.-xed horn on each side at base 

 3 lines long, the sides slightly tubercled, resembling Chamisso's 6'. tuberculatum, 1. c. fig. d, also 

 figured in Wight, Icon. vi. 5, t. 1948, fig. 3. In the several forms, common in various countries, 

 the fruit varies greatly, having the .sides often more or less covered with .small tubercles and some- 

 times crested, tiie margin wingless or surrounded by a, toothed wing, or bearing 2 to several 

 reflexed prickles, and the style variable in length and thickness. 



Order XCI. BETULACE^. 



Monoecious trees or shrubs, with deciduous simple and toothed alternate leaves, 

 distinct caducous stipules, scaly buds, and flowers sessile at or on the base of scaly- 

 bracts of the terminal or lateral aments, usually 2 or 3 within each bract ; the 

 staminate with a 4-lobed or scaledike perianth and 2 or 4 stamens ; the pistillate 

 naked ; bracts enlarging and becoming rigid in fruit ; ovary of two 1-ovuled cells 

 (one often empty), crowned with 2 sessile tiliform stigmas, becoming a winged or 

 angled nutlet. Seed anatropous, pendulous, Avith no albumen. Embryo straight 

 and radicle superior ; cotyledons flat, foliaceous in germination. Young aments res- 

 inous-coated. The two genera are widely distributed through the temperate and cold 

 climates of the northern hemisphere. 



1. Betula. Stamens 2, with bifurcate filamerts and separate anther-cells. Bracts 3-lobed, 



becoming coriaceous and caducous. Nutlet broadly winged. 



2. Alnus. Stamens 4 ; anther-cells contiguous. Bracts entire, becoming woody, persistent. 



Nutlet not winged. 



1. BETULA, Tourn. Birch. 

 Bracts of staminate aments shield-shaped, including 2 bractlets and 3 flowers ; 

 calyx of a single entire scale-like sepal. Stamens 2, Avith bifld filaments, the 

 branches bearing the distinct anther-cells. Bracts of pistillate aments 3-lobed, 2-3- 

 flowered, imbricated, coriaceous in fruit and deciduous. Nutlets lenticular, sur- 

 rounded by a broad membranous wing and tipped by the spreading stigmas. — Trees 

 or shrubs with smooth laminated outer bark, the flowers appearing with or before 

 the leaves ; staminate aments long and drooping, solitary or in pairs, from leafless 

 lateral or terminal buds ; fertile aments oblong or cylindrical, solitary or racemose, 

 from lateral 3 - 5-leaved buds. 



About 30 species are described, a third of which are found in the northern and eastern portions 

 of America. The wood is tough and usually fine-grained, valuable for cabinet-work. 



1. B. occidentalis, Hook. Becoming 10 or 20 feet high, with close dark- 

 colored Ixuk (at length light brown) ; branches more or less resinous-dotted at the 

 extremities : leaves thin, broadly ovate, acute, truncate or rounded or somewhat 

 cuneate at base, 1 to 1| inches long, with short glandular-tipped serratures and 

 often obscurely lobed, somewhat resinous above, smooth or slightly api)ressed-vill()us 

 beneath ; petioles slender, 3 to 5 lines long : fruiting aments oblong-cylindric, 8 to 

 12 lines long, with pubescent ciliate divaricately 3-lobed bracts : wings of the nut- 

 let as broad as the body or broader. — Fl. Bor.-Am. ii. 155; Nutt. Sylva, i. 22, 

 t. 7 ; Watson, Bot. King Exp. 323, t. 35. 



In the eastern canons of the Sierra Nevada above Owen's Valley, at an altitude of from 4,.'')00 

 to 10,000 feet, where it is reported as abundant and often the main reliance of the settlers for 

 timber for fencing and other purposes; Surprise Valley, Modoc County (Lonimm), and fommon 

 along streams in Siskiyou County, where it is known as "Black Birch." It is fiecjuent from 

 Washington Territory to the Saskatchewan, and in the Rocky Mountains to New Mexico. 



