BETULAOEAE 69 



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

 nuts small, subtended or enclosed by an involucre. 



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



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 ament becoming a coriaceous 

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



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

 winter buds scaly; strobile coriaceous Belvla. 



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

 and persistent; stamens 4; winter bu(is without scales . -Aldus. 



OSTKYA 



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 

 ovar^; 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 

 beeds usually do not germinate until the second year. 



