BETULACEAE 69 



II. Staminate flower without bractlets ; pistillate anient spike-like; 

 nuts small, subtended or enclosed by an involucre. 



a. Fruiting bractlet flat, 2 cleft, foliaceous CarpinuH. 



b. Fruiting bractlet bladder-like, entire or 3 lobed. 



1. Fruiting bractlet entire Ostrya. 



2. Fruiting bractlet 3 lobed Ostryopsis. 



B. Staminate flowers 3-6 in the axils of the scales, with calyx; 

 pistillate flower without calyx, the anient becoming a coriaceous 

 or woody strobile; nuts without involucre, more or less winged. 



I. Pistillate anient solitary, the scales deciduous; stamens 2; 

 winter buds scaly; strobile coriaceous Betida*. 



II. Pistillate anient racemose, the scales becoming thick, woody 

 and persistent; stamens 4; winter buds without scales. .Alaus. 



OSTRYA 



Small trees. Buds scaly, pointed. The staminate flower buds in 

 terminal, naked catkins; the pistillate flower buds enclosed in axillary 

 scaly buds. Leaves deciduous, doubly serrate, stalked, pinnately veined, 

 stipules oblong or lanceolate, deciduous. Flowers monoecious, apetalous; 

 the staminate clustered, in pendulous, terminal catkins; pistillate catkins 

 from axillary buds, erect, each scale bearing 2 ovaries, calyx adnate to the 

 ovary; ovary inferior, 2 celled, 1 ovuled; each pistil enclosed in a hairy 

 sac-like involucre formed by the union of the bracts and the bracteoles. 

 Fruit a stalked strobile composed of the imbricated, inflated, bladder-like 

 involucre enclosing a nutlet. Nutlet ovoid, compressed, sessile, crowned 

 by the remnant of the calyx, conspicuously ribbed. Seeds solitary. 



4 species in N. America, Europe, and Asia. 



The species are so closely allied that botanists are disposed to regard 

 them as geographical variants of the same species. The genus is easily 

 recognized by the cone or hop-like fruits composed of flattish, inflated, 

 membranous, bladder-like bracts each enclosing a small, bony nutlet. 

 The tree is slow growing and never attains a large size, and the hard, close- 

 grained wood has little commercial value, although locally useful:' The 

 seeds usually do not germinate until the second year. 



