The Spanish, or sweet chestnut is allied to the oak and beech. It has long, narrow leaves; it flowers in July. Its fruit is enclosed in a prickly husk, which splits into four when the nuts are ripe in October.
The birch.—The birch ([Fig. 116]) is a slender, graceful tree, with bark streaked with brown, yellow, and silvery patches. Its leaves ([Fig. 117]) are rather small, and their glossy, dark-green colour contrasts pleasantly with the brownish-purple of the young twigs. Both male and female flowers are arranged in catkins ([Fig. 117]). The male flowers appear in autumn, but do not open until spring, when the newly-formed female flowers are ready. The female catkins (a, [Fig. 117]) are much smaller than the male (b).
Fig. 118.—The Hazel; leaf, flowers and fruit. 1, a flowering branch (× ⅔); 2, a male flower (× 2); 3, a stamen (× 4); 4, a female flower cut through longitudinally; 5, fruit with cup (× ⅔); 6, fruit without cup; a foliage leaf.
Fig. 119.—The Alder; leaf, flowers and fruit. 1, Branch with male catkins (a) and female cones (b) (× ⅔); 2, male flowers (× 2⅔); 3, female cone; 4, two female flowers; 5, ripe cone (× ⅔); 6, a fruit (× 1).
The hazel and alder develop their flowers in the year preceding their opening. The female flowers of the hazel ([Fig. 118]) look somewhat like buds, but may be distinguished by the red stigmas. The fruit is a nut, enclosed by a sheath of soft bracts. The seeds are largely dispersed by squirrels. The alder grows on the banks of streams; its female flowers (Fig 119, b) are arranged in short catkins, which may be called cones. The ripe cone (5, [Fig. 119]) contains two nuts at the base of each scale. The fruits fall into the stream, and float away, perhaps to germinate at a considerable distance.