306 COMMON TREES AND SHRUBS 



are eight stamens together with a pistil which is superior, 

 and consists of two, sometimes three, united carpels. 



The ovary is two-celled, each cell having two ovules, but 

 only one develops into a seed. The lateral flowers are often 

 staminate, and the pistil, when present, is small and abortive 

 (Fig. 202, 3). In the complete flowers the stamens ripen 

 before the stigmas. 



Honey is secreted on the prominent disk at the base of 

 the pistil (4 d), and, being exposed, is accessible to short- 

 tongued insects like flies, which freely visit the flowers. 



The fruit or ' key ' (see p. 214) is a double samara 

 (5), and when ripe, splits into two half-fruits. They fall 

 spirally and the wing aids in wind-dispersal, but, except in 

 high winds, they are not carried far from the parent tree. 



Horse-Chestnut 



The Horse-Chestnut (Aesculus Hippocastanum) (Figs. 66, 

 68, 69, and 103) is a native of Greece and Asia, where its 

 seeds are ground and mixed as a medicine with horses' food ; 

 hence its specific name, and the English equivalent ' Horse- 

 Chestnut '. Another explanation of the name is that 

 ' horse ' or ' coarse ' is applied to it to distinguish it from 

 the edible Chestnut (Castanea). It is commonly planted 

 in Britain as an ornamental tree. It grows seventy to 

 eighty feet high, with an erect trunk, three to four feet thick 

 at the base, and with a broad pyramidal crown. The bark 

 is smooth for many years, and then becomes grooved and 

 scaly. As in the Sycamore, branching is monopodial, and 

 in the young trees very regular, with a tendency for the 

 inner branches to be smaller. The branches curve down- 

 wards and outwards, and in open situations the end twigs 

 are markedly upturned and end in very large, sticky, red- 

 brown buds, the structure of which has already been 

 studied (pp. 108-13). 



