GENUS 2. 



WILLOW FAMILY. 



38. Salix glauca L. Northern Willow. 

 Fig. 1488. 



Salix glauca L. Sp. PI. 1019. 1753. 



S, atra Rydb. Bull. N. Y. Bot. Card, i : 272. 1899. 



S. labradorica Rydb. Bull. N. Y. Bot. Card, i : 274. 1899. 



A low arctic shrub, with terete brown twigs, the 

 young shoots and leaves densely tomentose, becoming 

 glabrate when old. Leaves elliptic or elliptic-lanceo- 

 late, entire, obtuse or acute at the apex, narrowed 

 at the base, i'-3' long, i'-i' wide; petioles i"-s" 

 long; stipules deciduous; aments borne on short 

 leafy branches, the staminate dense, about i' long, 

 the pistillate 2'-$' long in fruit, rather loose ; stamens 

 2; filaments distinct; bracts persistent, yellowish or 

 brownish, densely white-villous; capsule ovoid-conic, 

 densely white-tomentose, sessile or very short- 

 pedicelled, 3"~4" long; style about as long as the 

 stigmas. 



Greenland and Labrador to Alaska. Also in arctic and 

 alpine Europe and Asia. The American races differ 

 slightly from those of the Old World. Summer. 



39. Salix anglorum Cham. Brown's Willow. 

 Fig. 1489. 



Salix arctica R. Br. Ross' Voy. cxliv. 1819. Not Pall. 



Salix anglorum Cham. Linnaea 6: 541. 1831. 



S. Brownii Lundst. Nov. Act. Soc. Sci. Ups. 16: 6. 1877. 



A low, much branched shrub, the twigs 4-angled, 

 slender. Leaves oblong or lanceolate, glabrous or 

 sometimes ciliolate, mostly acute at the apex, entire, 

 narrowed at the base, short-petioled, i'-3' long, 3"- 

 12" wide, blackening in drying, the lower surface 

 pale or glaucous, the margins not revolute; stipules 

 narrow, deciduous; aments borne on short leafy 

 branches, large, the pistillate i'-2j' long in fruit; 

 bracts villous, persistent, obovate, obtuse, dark 

 brown; stamens 2; filaments glabrous; style filiform, 

 much longer than the stigmas ; capsule ovoid-conic, 

 tomentose, short-pedicelled, acute, 2"-^" long. 



Labrador to Alaska, and in the Rocky Mountains to 

 Colorado. Summer. 



Salix Macouni Rydberg (S. vacciniformis Rydberg), 

 of Labrador, Hudson Bay and Quebec, differs in having 

 smaller aments and leaves remaining green in drying. 

 Salix groenlandica (Anders.) Lundst., of high arctic regions has smaller leaves, darkening 

 in drying. 



Family 6. BETULACEAE Agardh, Aphor. 208. 1825. 



BIRCH FAMILY. 



Monoecious or very rarely dioecious trees or shrubs, with alternate petioled 

 simple leaves, and small flowers in linear-cylindric oblong or subglobose aments. 

 Stipules mostly fugacious. Staminate aments pendulous. Staminate flowers 1-3 

 together in the axil of each bract, consisting of a membranous 2-4-parted calyx, 

 or none, and 2-10 stamens inserted on the receptacle, their filaments distinct, their 

 anthers 2-celled, the anther-sacs sometimes distinct and borne on the forks of the 

 2-cleft filaments. Pistillate aments erect, spreading or drooping, spike-like or 

 capitate. Pistillate flowers with or without a calyx adnate to the solitary 2-celled 

 ovary; style 2-cleft or 2-divided ; ovules i or 2 in each cavity of the ovary, 

 anatropous, pendulous. Fruit a small compressed or ovoid-globose, mostly 

 i-celled and i-seeded nut or samara. Endosperm none. Cotyledons fleshy. 



Six genera and about 75 species, mostly natives of the northern hemisphere. 



Staminate flowers solitary in the axil of each bract, destitute of a calyx ; pistillate flowers with a calyx. 

 Staminate flowers with no blactlets ; pistillate aments spike-like ; nut small, subtended by or 



enclosed in a large bractlet. 



Fruiting bractlet flat, 3-cleft and incised. i. Carpinus. 



Fruiting bractlet bladder-like, closed, membranous. 2. Ostrya. 



Staminate flowers with 2-bractlets ; pistillate flowers 2-4, capitate; nut large, enclosed by a 



leafy involucre. 3. Corylus. 



Staminate flowers 3-6 together in the axil of each bract, with a calyx ; pistillate flowers without a calyx. 

 Stamens 2 ; filaments 2-cleft ; fruiting bracts 3-lobed or entire, deciduous. 4. Betula. 



Stamens 4 ; anther-sacs adnate ; fruiting bracts woody, erose or s-toothed, persistent. 5. AInus. 



