192 



TREES OF NORTH AMERICA 



veloped in early summer from lateral buds near the ends of short lateral branchlets 

 of the year and coated while young with hoary tomcntum, naked and conspicuous 

 during the winter, and composed of 3-14 stamens crowded on a pilose receptacle 

 adnate to the base of an ovate concave scale rounded and abruptly short-pointed at 

 the apex, ciliate on the margins, longer than the stamens; filaments short, 2-branched, 

 each branch bearing a 1-celled half-anther hairy at the apex; pistillate in erect lax 

 aments terminal on short leafy branches of the year, in pairs at the base of an 

 elongated ovate acute leaf-like ciliate scale persistent until midsummer, each flower 

 inclosed in a hairy sack-like involucre formed by the union of a bract and 2 

 bractlets; calyx adnate to the ovary, denticulate on the free narrow border. Nuts 

 ovate, acute, flattened, obscurely longitudinally ribbed, crowned with the remnants 

 of the calyx, marked at the narrow base by a small circular pale scar, inclosed in 

 the much enlarged pale membranaceous conspicuously longitudinally veined reticu- 

 late-venulose involucres of the flower, short, pointed and hairy at the apex, hirsute 

 at the base, with sharp rigid stinging hairs, imbricated into a short strobile fully 

 grown at midsummer, and suspended on a slender hairy stem. 



Ostrya is widely distributed in the northern hemisphere from Nova Scotia to 

 Texas, northern Arizona, and to the highlands of southern Mexico and Guatemala in 

 the New World, and through southern Europe and southwestern Asia and in northern 

 Japan in the Old World. Of the four species now recognized two are American. 



Ostrya is the classical name of the Hop Hornbeam. 



CONSPECTUS OF THE NORTH AMERICAN SPECIES. 



Leaves oblong-lanceolate, acuminate or acute at the apex. 

 Leaves oval or obovate, acute or rounded at the apex. 



1. O. Virginiana (A, C). 

 2. O. Knowltoni (F). 



1. Ostrya Virginiana, K. Koch. Hop Hornbeam. Ironwood. 



Leaves oblong-lanceolate, gradually narrowed into long slender points or acute 

 at the apex, narrowed and rounded, cordate or wedge-shaped at the often unequal 



base, sharply serrate, with slender incurved callous teeth terminating at first in tufts 

 of caducous hairs, when they unfold light bronze-green, glabrous above and coated 

 below on the midribs and primary veins with long pale hairs, at maturity thin and 



