264 BE TULA 
are free from the bract at the time of fertilisation, but afterwards they 
unite with it to form the 3-lobed woody scale (F in figure) under the 
B. alba. A , bract, bracteoles, and perianth, of $ , from within, with sta. re- 
moved ; B , a stamen; C y floral diagram of A ; D , bract, bracteoles and firs, of $ 
from within ; E , the same with firs, removed ; F y the same at ripeness of seed ; G, 
floral diagram ofZ>. £=bract; a, = bracteoles offlr. 1, or bracts of firs. 2, 3. After 
Eichler. 
fruit (or rather the tissue beneath them grows up, carrying all up 
together; see p. 30). The 2-locular ovary gives rise to a i-seeded 
nut, attached to the scale. There is no perianth. 
Birch-wood is tough and is used for various purposes, e.g. for 
wooden shoes and for charcoal. The oil prepared from the bark is 
used in tanning Russia leather, to which it gives its peculiar fragrance. 
The bark of B. papyracea Ait. (N. Am.) is used in making canoes. 
Betulaceae. Dicotyledons (Archichl. Fagales). 6 gen. with 75 sp., 
chiefly N. temp. Shrubs or trees with undivided stipulate leaves. 
The seedling stems are radial in symmetry, but in the old branches 
the leaves are often 2-ranked and face upwards (p. 47). The mem- 
branous stipules soon drop off. Firs, monoecious, in terminal catkins ; 
the stem is thus sympodial. In the axils of the leaves of the catkins 
are small dichasial cymes, typically of 3 firs, (see Betula, &c.). The 
central fir. is often absent, and some of the bracteoles also. The S 
flr. is united to the bract and may have a perianth; sta. 2 — 10. The 
$ may have an epigynous perianth. Cpls. (2). Ovary inferior, 
2-loc. with 1 pendulous ovule in each loc. Some genera are chala- 
zogamic; see Chalazogamae. Nut 1 -seeded; seed exalbuminous. 
After fertilisation the bract and bracteoles grow into a scale- or cup- 
like organ which may remain attached to the fruit. Genera : Ostry- 
opsis, Carpinus, Ostrya, Corylus, Betula, Alnus. The order is 
placed in Querciflorae by Eichler, and united to Fagaceae (Cupu- 
liferae) by Benth. -Hooker. 
Biaxum Schott. Araceae (vn). 7 sp. Medit. 
Bicarpellatae (Benth. -Hooker). The 3rd series of Gamopetalae (p. 136), 
