310 COMMON TREES AND SHRUBS 



which are the largest, are short, and covered with velvety 

 black hairs. Though sometimes separated by a short 

 internode, the lateral buds are generally opposite and in 

 crossed pairs. A flattened appearance is given to the nodes 

 by the large leaf -bases in which the buds are partly embedded. 

 The leaf-scars are large and shield-shaped, with many 

 somewhat fused leaf -traces. The bud-scales are in crossed 

 pairs ; two to four may be seen on the outside, and, as 

 in the Horse-Chestnut and Sycamore, they are leaf -bases. 



The leaves, which appear late, are in crossed pairs, but 

 sometimes they are alternate (Fig. 204, 2). The base is 

 large and has no stipules ; the petiole and midrib are grooved 

 above, especially opposite to the leaflets ; hairs occur in 

 the groove, and sometimes small insects inhabit it. The 

 blade is large, compound pinnate, and with from seven to 

 thirteen leaflets, which are ovate, lanceolate, and irregularly 

 serrate ; the apex is long and pointed (acuminate). In 

 young trees, during damp weather, drops of water exude 

 from water-pores at the leaf-tips. When the leaves fall, 

 a separation-layer forms across the bases of the leaflets as 

 well as across the leaf-base. This occurs also in the Horse- 

 Chestnut. 



The Ash, like the Birch, is a light-demanding tree and 

 endures shade badly. When planted along with, and under 

 the shade of, quicker-growing Pines, the young main 

 shoot grows rapidly towards the light and so forms a tall, 

 slender trunk ; hence Pines, in such circumstances, are 

 called ' Nurses ' by foresters. 



The flowers appear in April or May and before the leaves. 

 The inflorescences (Fig. 204, 3) are dense, racemose cymes of 

 a dark purple colour, due to the purple-brown anthers 

 and stigmas. The flowers (4 and 5) are polygamous, i.e. 

 staminate, pistillate, and hermaphrodite flowers may 

 occur on the same tree, and sometimes the trees are 

 dioecious. The male flowers have no perianth, and consist 



