428 Betulace^e. 



THE HOP-HORNBEAM. Genus OSTRYA Scop. 



Trees of wide disti'ibutiou tliioughout the uorthern hemisphere, with scaly bark, slender 

 terete branchlets and hard rather close-grained wood. Four species are liuown. two of which are 

 North American. One of them (O. Knoicltoni Cov.,), as far as known, is found only in the 

 Grand Canyon of the Colorado Kiver in Arizona, and the other is a common tree widely dis- 

 tributed throughout the eastern United States and Canada. 



Leaves open and concave in the bud. more or less plaited on the nearly straight veins. 

 Floivers expanding before the leaves; staminate aments in clusters of a few each with short 

 stalks or sessile, developed the previous season near the ends of the branchlets and naked and 

 conspicuous during the winter ; stamens 8-4, crowded on a receptacle at the base of a broad 

 ovate pointed concave scale longer than the stamens ; filaments short, 2-branched. each branch 

 bearing a 1-celled half-ant licr liairy at apex; pistillate flowers in small loose suberect aments 

 terminating leafy shoots nnd with large pointe<l deciduous scales at the base of each of which 

 are 2 flowers each sundundiil with a tubular persistent accrescent involucre: calyx adnate 

 to the ovary ; style 2-branched. Fruit an ovoid flattened pointed nutlet, inclosed in an enlarged 

 pale membranous closed sac formed by the enlarged involucre and these together forming a 

 strobile very much resembling a hop, suspended by a slender stem. 



0><trt/(i is the classical Latin name of the European species. 



For species see pp. 116-111. 



\. Hen 



^^of tl 



THE BIRCHES. Genus BETULA L. 



The Birches constitute a considerable and important part of the forests of the Northern 

 Hemisphere of both the Old and the New Worlds. Although a few are shrubby species most 

 of them are large and handsome and often aromatic forest trees, some of excep'tional ornamental 

 kie with more or less laminate and resinous bark, very tough slender twigs and copious 

 watery and slightly saccharine sap. 



Leares serrate, dentate, or sometimes incisely lobed. usually thin, from scaly pointed 

 sessile buds; stipules scarious and fugacious. Flowers unfolding' with or before the leaves; 

 the staminate in pendulous often clustered sessile aments which form the previous season and 

 remain erect and naked during the winter at or near the ends of the branchlets and rapidly 

 develop expanding their golden flowers in early spring ; scales broad-ovate with the two lateral 

 flowers adnate to their bases ; calyx membranous, usually 4-lobed ; stamens 2 with short 

 2-parted filaments, each filament bearing and anther-cell ; pistillate aments small oblong or 

 cylindrical, usually peduncled, terminating short lateral 2-leaved branchlets and with closely 

 imbricated ,3-lobed persistent accrescent scales ; calyx v\-anting ; pistil with compressed sessile 

 ovary and 2 spreading persistent styles stigmatic at the apex. Fruit erect, inclined or 

 pendulous strobiles with thin woody 3-lobed scales and 3 laterally winged nutlets to each 

 scale and these with the scales falling away from the central axis of the strobile at maturity. 



Betula is the classical name of the Birch-tree. 



KEY TO THE SPECIES. 

 a Branchlets. etc.. not aromatic; strobiles 



b Cylindrical, with long slender peduncles; wings broader than nutlet; scales 



o Pubescent, lateral lobes broad and recurved: bark not easily separable into layers: 

 leaves with long slender petioles, long ai-uniinate and 



Deltoid, wide and mostly truncated at liasc. bright green B. populifolia. 



Ovate, mostly rounded or wedge-shaped at base, dull blue-green.. B. ccerulea. 

 o' Glabrous with spreading lateral lobes: leaves mostly ovate and rounded at base: bark 

 creamy white and separating freely into layers B. papyracea. 



V Oblong, slender, peduncled, mostly erect and lobes of scales linear-oblong : leaves acute. 



B. nigra, 

 a- Branch.lets and inner bark aromatic ; strobiles oblong-ovoid, subsessile. erect ; wings not 

 broader than nutlet ; leaves sharply 

 b Serrate ; scales of stobiles short glabrous and with rounded lateral lobes ; bark dark 

 brown and scaly B. lenta. 



V Doubly serrate, scales longer and with oblong lobes: bark yellow or silv^'-v and laminate. 



B. lutea. 

 For spt'cies xee pp. 11H-121' und the foUoKinci : 



Blur Birch. Betula ccerulea Blanch. A small tree occasionally ?,0 ft. in height with 

 trunk 8-10 in. in diameter recently described as found in southe-n Vermont and northern 

 Maine and may be found elsewhere in New England. It resembles the B. populifolia hut 

 is said to differ in having leaves rather ovate in outline, more cuneate at base and with dull 

 bluish green upper surfaces. The bark of trunk is described as being more lustrous and of a 

 pinkish white color. 



