214 THE CENTRAL AMERICAN RUBBER TREE 



which, under favourable conditions, may attain a height 

 of 160 to 180 ft. with a trunk 12 or 13 ft. in circumference 

 at 3 ft. from the ground. The bark is usually rather 

 smooth, soft, and light grey, though there is some varia- 

 tion in the colour. The young branches are densely 

 covered with greenish-yellow or brown hairs. The leaves 

 are very large, ranging from 12 to 20 in. in length and 

 from 4 to 7 in. in breadth, opposite, and hang from the 

 branches in two pendant rows ; they are light green, 

 oblong, cordate at the base, and the veins are very pro- 

 minent below. The under surface of the leaves is covered 

 with greenish-yellow hairs, which are especially numerous 

 on the midrib and larger veins, and project in little tufts 

 from the margin.; the upper surface is much less hairy 

 and darker in colour. The flowers are male (staminate) 

 and female (pistillate), and both forms usually occur on 

 the same tree, although young trees frequently bear 

 only male flowers. The fruits, which occur in clusters, 

 are orange-coloured and fleshy, each containing an ivory- 

 white seed, J to -|- in. in diameter, with a very thin papery 

 seed-coat. The seeds only retain their vitality for a 

 short time. 



A striking peculiarity of Castilloa elastica is the pro- 

 duction, during the early stages of growth, of temporary 

 deciduous branches, which, although not more than 1 in. 

 in diameter at the base, are often 10 to 12 ft. in length. 

 These branches drop off after a time, bemg detached 

 from the trunk by the rupture of a special layer of tissue 

 at the base. As a general rule, the permanent branches 

 do not develop before the third or foiurth year. 



Distribution. — Castilloa elastica is found growing wild 

 in JMexico south of 22° N. latitude, and thence extends 

 through all the States of Central America into Colombia ; 

 it also occurs on the western slopes of the Andes in 

 Ecuador and Peru. 



In Mexico the rubber area includes the States of Vera 

 Cruz, Oaxaca, Chiapas, Tabasco, and Campeche, but 

 only a comparatively small area of this territory is actually 

 suitable for the cultivation of the tree. Dm'mg recent 

 years very large plantations of Castilloa trees have been 

 formed in Southern Mexico, particularly in the Soconusco 

 and Palenquc districts of the State of Chiapas. 



Castilloa trees are abundant in certain districts of 



