200 TREES OF NORTH AMERICA 



at base, pointed at apex, only slightly angled, faintly tinged with red, with a shell rarely 

 more than T ^' in thickness; seed small and sweet. 



A tree 30-40 high, with a trunk 12'-18' in diameter, stout often contorted branches and 

 slender branchlets covered at first with rusty pubescence mixed with fascicled hairs and 

 pubescent or glabrous during their first winter. Winter-buds ovoid, acute, covered with 

 rusty pubescence mixed with yellow scales, often furnished near the apex with tufts of 

 white hairs, the terminal \ r long and about twice as large as the compressed axillary 

 buds. 



Distribution. Dry rocky hills, Allenton, Saint Louis County, Missouri. Distinct from 

 other forms of Carya Buckleyi in the often indehiscent fruit and more numerous and 

 longer fascicled hairs, and possibly better considered a species. 



DC. BETULACE^. 



Trees, with sweet watery juice, without terminal buds, their slender terete branchlets 

 marked by numerous pale lenticels and lengthening by one of the upper axillary buds 

 formed in early summer, and alternate simple penniveined usually doubly serrate deciduous 

 stalked leaves, obliquely plicately folded along the primary veins, their petioles in falling 

 leaving small semioval slightly oblique scars showing three equidistant fibro-vascular 

 bundle-scars; stipules inclosing the leaf in the bud, fugacious. Flowers vernal, appearing 

 with or before the unfolding of the leaves, or rarely autumnal, monoecious, the staminate 

 1-3 together in the axils of the scales of an elongated pendulous lateral ament and composed 

 of a 2-4-parted membranaceous calyx and 2-20 stamens inserted on a receptacle, with dis- 

 tinct filaments and 2-celled erect extrorse anthers opening longitudinally, or without a 

 calyx, the pistillate in short lateral or capitate aments, with or without a calyx, a 2-celled 

 ovary, narrowed into a short style divided into two elongated branches longer than the 

 scales of the ament and stigmatic on the inner face or at the apex, and a single anatropous 

 pendulous ovule in each cell of the ovary. Fruit a small mostly 1-celled 1-seeded nut, the 

 outer layer of the shell light brown, thin and membranaceous, the inner thick, hard, and 

 bony. Seed solitary by abortion, filling the cavity of the nut, suspended, without albu- 

 men, its coat membranaceous, light chestnut-brown; cotyledons thick and fleshy, much 

 longer than the short superior radicle turned toward the minute hilum. 



Of the six genera, all confined to the northern hemisphere, five are found in North 

 America; of these only Corylus is shrubby. 



CONSPECTUS OF THE NORTH AMERICAN ARBORESCENT GENERA. 



Scales of the pistillate ament deciduous; nut wingless, more or less inclosed in an involucre 

 formed by the enlargement of the bract and bractlets of the flower; staminate flowers 

 solitary in the axils of the scales of the ament; caylx 0; pistillate flowers with a 

 calyx. 



Staminate aments covered during the winter: involucre of the fruit flat, 3-cleft, foli- 



aceous. 1. Carpinus. 



Staminate aments naked during the winter: involucre of the fruit bladder-like, closed. 



2. Ostrya. 



Scales of the pistillate ament persistent and forming a woody strobile ; nut without an in- 

 volucre, more or less broadly winged; staminate flowers 3-6 together in the axils of the 

 scales of the ament; calyx present; pistillate flowers without a calyx. 

 Pistillate aments solitary, their scales 3-lobed, becoming thin, brown, and woody, de- 

 ciduous; stamens 2; filaments 2-branched, each division bearing a half -anther; 

 winter-buds covered by imbricated scales. 3. Betula. 



Pistillate aments racemose, their scales erose or 5-toothed, becoming thick, woody, and 

 dark-colored, persistent; stamens 1-3 or 4; filaments simple; wings of the nut often 

 reduced to a harrow border; winter-buds without scales. 4. Alnus. 



