TREES AND SHRUBS. 401 



only two flowers (Fig. 168, c) surrounded by a four-lobed cup 

 covered with soft outgrowths ; each flower has a four- to 

 eight-toothed perianth above the three-chambered ovary (two 

 ovules in each chamber), and the style has three stigmas. 



After fertilisation the cup becomes woody and its out- 

 growths stiff or even spiny ; about October the four lobes 

 spread out and let the nuts escape (Fig. 168, D). The nut 

 is filled by the embryo, which has two folded cotyledons. 

 On germination the cotyledons are carried up and spread out 

 as broad green leaves. For several years the young plant 

 grows very slowly ; each year the end of the stem bends over 

 so that the leaves (set in two rows) shall not shade each other, 

 then the upward growth for the next year is carried on by a 

 bud on the top of the bend. 



[The Copper Beech is a variety of Common Beech in 

 which the epidermis of the leaf contains a red pigment (dis- 

 solved in the sap of the epidermal cells) ; the mesophyll 

 consists of green tissue, as in the ordinary Beech.] 



[39O. The Sweet or Spanish Chestnut has long, oval, 

 toothed leaves, which remain on the tree till late autumn, 

 when they assume a rich golden colour. The flowers are 

 produced in long spikes during July, the male flowers being 

 situated on the upper parts of the spike, and the female 

 flowers near the base. The former soon wither and fall, 

 while the latter develop into tiny husks, lined by silky hairs, 

 and each containing from two to five pointed nuts, some of 

 which do not fully develop. The fruit is ripe in September, 

 and falls in October, when the cupule splits and exposes 

 the nuts. The seeds ripen in Britain only in warm seasons 

 or favourable localities.] 



391. Elm (Figs. 169, 170). There are two kinds of Elm 

 in Britain, the Common or English Elm ( Ulmus campestris) 

 and the Wych, Scots, or Mountain Elm (Ulmus mon- 

 tana) ; roughly speaking, most Elms growing south of the 

 Trent belong to the former species, while most Elms north 

 of the Trent belong to the latter. 



In both Elms the bark is rough and shoots are often pro- 

 duced from the lower part of the trunk. Both grow into 

 tall trees (up to about 120 feet), and have short- stalked 

 8. B. 26 



