514 



FAGACEAE 



3. Alnus rhombifolia Nutt. 

 White Alder. Fig. 1247. 



Alnus rhombifolia Nutt. Sylva 1: 33. 1842. 



A tree, often 25 m. high, with a straight 

 trunk 6-10 dm. in diameter. Leaves ovate, 

 5-7.5 cm. long, rounded or acute at apex, 

 cuneate at base, finely or coarsely and 

 doubly serrate, becoming dark green, 

 glabrous or minutely pubescent above, light 

 yellow-green and puberulent beneath ; peti- 

 oles pubescent, flattened ; cones oblong, 

 8-12 mm. long, their scales slightly thick- 

 ened and lobed at apex ; nutlets broadly 

 ovate, with a narrow thin margin. 



Along streams. Transition and Upper Sonoran 

 Zones; southern British Columbia and northern 

 Idaho south through the Pacific States to northern 

 Lower California. Type locality: Monterey, Cali- 

 fornia. 



4. Alnus tenuifolia Nutt. Thin-leaved Alder. 



Alnus tenuifolia Nutt. Sylva 1: 32. 1842. 



Alnus incana virescens S. Wats. Bot. Calif. 2: 81. 1880. 



Alnus occidentalis Dippel, Handb. Laubh. 2: 158. 1892. 



Shrub 1-2 m. high or sometimes a small tree 10 m. 

 high with a trunk 20 cm. in diameter. Leaves 5-10 cm. 

 long, ovate to oblong, acute at apex, rounded to cordate 

 or sometimes cuneate at base, usually acutely and 

 deeply lobed and doubly serrate, pubescent when 

 young, becoming dark green and glabrous above, yel- 

 low-green and glabrous or finely pubescent beneath; 

 cones ovoid to oblong, 8-12 mm. long, their scales 

 truncate and 3-lobed at the much thickened apex ; nut- 

 lets nearly orbicular, with a very narrow membranous 

 border. 



Borders of streams, lakes and mountain meadows. Arid 

 Transition and Canadian Zones; Yukon Territory and British 

 Columbia to New Mexico and Lower California. The common 

 alder of the Sierra Nevada and the eastern slopes of the 

 Cascades. Type locality: Rocky Mountains, and the Blue 

 Mountains. 



Fig-. 



1248. 



Family 29. FAGACEAE. 

 Beech Family 

 Trees and shrubs with deciduous or evergreen alternate petioled leaves and 

 small usually deciduous stipules. Flowers monoecious, without petals, the stam- 

 inate in pendulous or erect aments or sometimes in peduncled heads, the pistillate 

 solitary or in small clusters, subtended by an involucre which becomes ^ bur or 

 cup. Staminate flowers with 4-7-lobed calyx and 4-20 stamens. Pistillate flow- 

 ers with a 4-8-lobed calyx, adnate to the 3-7-celled ovary. Ovules 1-2 in each 

 cell, pendulous, only 1 in each ovary maturing. Styles as many as the cells of the 

 ovary, linear. Fruit a 1 -seeded nut with bony exocarp. Endosperm none ; cotyledons 

 large and fleshy. 



A family of six genera, mainly confined to the northern hemisphere, and all represented in North 

 America except Notlwfagus, which 'is restricted to the southern hemisphere. 



Fruit composed of 1-3 nuts, enclosed in a spiny bur-like involucre. 1. Castanopsis. 



Fruit a single nut surrounded at base by a scaly cup-like involucre. ., - • . . u ^ • ^u . 



Staminate aments densely flowered, erect, their flowers clustered m the axils of persistent bracts; pistillate 



flowers clustered at the base of the staminate aments. 2. Lithocarpm 



Staminate aments loosely flowered, spreading or drooping, their flowers solitary in the axils ot tne 

 thin caducoTis bracts; pistillate flowers in axillary clusters. 3. (Juercus. 



