SPMNG-FtOWiJMlNG TREES AND SHMUBS 75 



and each flower has from four to eight stamens, with hairy anthers 

 that produce abundance of pollen. The pistillate catkins are 

 small, oval, and sessile, hardly to be distinguished from the foliage 

 buds until they protrude their bright crimson stigmas. The minute 

 flowers are enclosed in overlapping bracts which afterwards form 

 the leafy cupules of the large woody nuts ; and each one has a two- 

 celled ovary and two styles. 



Our forest trees include three representatives of the order 

 Betulacece — the Common Birch, the Dwarf Birch, and the Alder. 

 The first of these, the Common Birch, Silver Bu'ch, or Lady of the 

 Woods {Betula alba), is at once recognised by its smooth, silver- 

 white bark, which peals off in horizontal strips ; its copper-brown 

 branches ; and its very slander, drooping twigs. The leaves are 

 small, rhomboid or triangular, with an irregularly doubly-serrate 

 margin, a sharp apex, and veins very prominent on the under side. 

 They are also provided with long stalks which, together with the 

 slender character of the weeping twigs, allow" them to be moved by 

 the shghtest breeze. The male and female flowers are in separate 

 catkins, the former of which may be seen on the tree throughout 

 the winter, but do not bloom until April or May. Both are at 

 first erect, but the staminate catkins droop as they mature, and 

 shed abundance of yellow pollen. The flowers have three-lobed, 

 deciduous, scale-like bracts ; the male ones consist of two stamens 

 with forked filaments ; and the females of a flattened, two-celled 

 ovary. The female catkins droop as they ripen, each one producing 

 a large number of minute, one-seeded and broadly-winged fruits 

 which are easily dispersed by the wind. Two varieties of this tree 

 occur, one with the leaves and twigs covered with downy hairs, 

 and the other with leaves of an oval-cordate form. 



The Dwarf Birch {B. nana) is a mere shrub, seldom exceeding two 

 feet in height, and is to be found only in some of the mountainous 

 districts of Scotland. It has rounded, crenate leaves, with short 

 stalks ; and the wings of the fruit are very narrow. 



The Alder {Alnus glutinosa) is common in wet woods, and 

 especially along the banks of streams in wooded valleys. Some of 

 the mountain streams of the West of England, Wales, and Scotland, 

 are bordered with almost continuous fines of Alder for miles together. 

 This tree has a very dark grey bark, and the young branches are more 

 or less triangular in form. The leaves are round, with a wedge- 

 shaped base, and are green on both sides. They have very short 

 stalks, are very blunt, and have a wavy, serrate margin. When 



