CATKIN-BEARING TREES 283 



m.c) are pendulous, and one and a half to two inches long 

 when open. Each bears a number of bracts, and within 

 each bract are two smaller bracts (3 and 4 br.). The flower 

 consists of four halved or split stamens. The filament is 

 divided into two, and each bears at its end half an anther. 

 Thus the flower appears to have eight stamens. 



The female catkin (i/.c) resembles a leaf-bud, but is 

 rather larger, and, when mature, bright red stigmas 

 project from it. Its outer structure is like a leaf-bud, and 

 consists of a covering of brown scales followed by stipules 

 and small leaves. In the centre are four or five bracts, 

 each with two flowers in their axils (5). The ovary is 

 inferior and bears a minute perianth (pe) ; on the top are 

 two long red stigmas. At the base is a cupule composed of 

 three scales (cu). 



After fertilization, the wall of the ovary hardens into 

 a woody shell, the perianth and stigmas shrivel up, and the 

 three scales at the base enlarge and form a leafy cupule 

 enclosing the nut (7 and 8). The seed is attached by a long 

 stalk, has a thin brown testa, a small radicle and plumule, 

 and two large cotyledons stored with oil (8 c). 



Birch 



The Birch (Fig. 188) is characteristic of dry upland woods 

 and heaths, and occurs frequently in the wet fen woods. It 

 is at once recognized by its white, papery bark, and slender 

 switch-like branches. It is a small graceful tree, the trunk 

 being from eight inches to a foot in diameter and attaining 

 a height of forty to fifty feet. The base is covered with a 

 rugged black bark ; above, it is white and shining, and peels 

 off in thin flakes ; it is marked transversely by long dark 

 brown lenticels. The younger branches are brown at first, 

 changing later to white. 



Two species (and several varieties) occur, and are most 

 readily distinguished by their young shoots. The common 



