350 THE VEGETABLE WORLD. 
calyx, with very small denticulated limbs, and a lower ovarium 
- with two cells, each containing a suspended anatropal ovule. 
This ovarium is surmounted by two long styles of a lively red. 
At the period of fructification the involucrum has undergone great 
development ; it has become foliaceous, a little fleshy, and slightly 
bell-shaped at its base, opening at the summit and containing a 
fruit, or nut, which is an achenium, in consequence of the abortion 
of one of the cells, and of the ovule, which it encloses. The seed, 
with slight membranous shell, contains an embryo destitute of 
albumen, under a slight integument: cotyledonous, smooth on the 
surface of one side, and convex on the other. Ba 
The common Yoke Elm, or Hornbeam (Carpensis betulus), when 
allowed to attain its natural dimensions, is a graceful tree, rising 
to the height of twelve to thirty feet, with a slightly smooth and 
ashy grey bark, and somewhat resembling the Beech in its appear- 
ance. The male flowers are disposed in cylindrical catkins, the 
imbricated scales of which directly protect from six to twenty 
stamens, with short bifurcated filaments and unilocular anthers 
barbed at the summit. The female flowers are disposed in clusters, 
the exterior with caducous bracts, of which each bear two unl- 
floral involucrum, presenting an appearance very analagous to those 
of the Hazel-tree. The fruit has a foliaceous, veined, reticula 
cupule, with three lobes, the middle one of which is much larger 
than the other two. The most important principle of the wood 
of the Yoke Elm is in its caloric power. It is an excellent fire-, 
wood. It is much used in the fabrication of certain tools, and 
parts of machines which are subjected to much friction, and where 
great durabiltiy is necessary ; but it is coarse, and in consequence of 
the larger size of its medullary processes it is unfitted for cabinet 
work. The Hornbeam is an indigenous British tree, very comme? 
in copses, and is frequently pollarded by the farmer. When checked 
and stunted in this way it retains its withered leaves all the winters 
and is useful where winter shelter is required. The wood ni 
anciently used as yokes for cattle, hence its popular and scientific 
name from the Celtic word Car, wood, and pinda, head. 
The Oaxs (Quercus) are monacious trees with simple alternate 
leaves, each having two caducous stipules. The male flowers fe 
ed in filiform catkins, slender, interrupted, and pe nden oe 
