128 THE FLORA OF THE ALPS 
5. CARPINUS, L. 
Fruit 1-celled, 1-seeded, enclosed in the greatly enlarged 
leafy lobed involucre. 
C. Betulus, L., Hornbeam ; frequent. 
6. OSTRYA, Scop. 
Female flowers in strobiliform catkins; fruit I-seeded, 
enclosed in the bladdery papyraceous involucre. 
O. carpinifolia, Scop.; leaves oval, acuminate, slightly 
cordate, doubly serrate; Grisons, Ticino, rare. 
Order LXXXII.—BETULACE. 
Flowers unisexual, moncecious; male flowers in pen- 
dulous catkins, female flowers beneath the scales of the 
female catkins; stamens 2-4; sepals o in female flowers; 
ovary inferior, 2-celled, with one ovule in each cell; Tem- 
perate and Arctic Zones. 
1. BETULA LL. 
Stamens 2; scales of female catkin thin, deciduous, 
3-fid. 
B. alba, L. (verrucosa, Ehrh.), our common Birch. J. 
pubescens, Ehrh. (glutinosa, Fr.); leaves orbicular or 
rhomboid, pubescent beneath, fruit with a broad wing; 
peat-bogs, local. L. zztermedia, Thom.; resembling the 
last, but a shrub; peat-bogs; Jura, rare. &. nana, L.; 
a small shrub, I-3 ft., female catkins erect, sessile, 
leaves broader than long, crenate; peat-bogs at a high 
elevation ; Switzerland (rare), Jura. 
