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“ The Manihot species, except Manihot Glaziovii, which is of a 
doubtful value as a rubber producer, grow too low. To this it must 
be added that the branches of all species of Manihot are very 
brittle, and that these trees prefer soil and climatic conditions 
which do not suit the cacao tree. 
“ Castilloa elastica, therefore, remains as the rubber tree most 
likely to give satisfaction, and it is probably also this tree which 
has most frequently been tried and recommended. A native of the 
same countries as Theobroma Cacao, its general climatic require- 
ments are the same. As regards soil, Castélloa thrives well on any 
good cacao land, but it is less particular, and will grow well on 
both lighter and heavier soils when the drainage is satisfactory. 
Castilloa elastica, like the cacao, prefers much water and atmospheric 
humidity, but it is very susceptible to damage through the least 
stagnation of subsoil water and acidity of soil. 
“ Although Castilloa in its native country is found growing in 
the forests it is not really a forest tree, but a ‘Tree weed’ as it 
has keen termed by Mr. O. F. Cook, in his report on ‘ The Culture 
of the Central. American Rubber Tree,’ Washington, 1903, by 
which term he understands a tree which can not grow up in the 
natural forest, but will develop rapidly on clearings, old garden 
sites, &c., where the slower-growing forest trees follow and 
surround it. In cultivation it is able to develop to perfection 
without shade, even on rather dry land, though it grows more 
rapidly when slightly shaded during the first years. 
oe On fair cacao land, Castilloa will reach a height of 25 to 30 feet 
within the first 4 years, and it is only when the tree is about 3 years 
old that it commences to develop permanent branches ; before this 
the only branches developed are pseudo-branches which, like the 
leaves, are shed every year. The pseudo-branches carry all the 
foliage of the tree, and when the growth is healthy the development 
both on the main stem and on the permanent branches is very rapid. 
The permanent branches remain few, but with their abundance of 
pseudo-branches, they form a dense crown affording good shade. 
“In localities where dry weather prevails during the months of 
March and April, the habit of Castilloa is decidedly deciduous, and 
it drops all its pseudo-branches during a short period ; while in 
districts where the spring weather is damp the change of foliage is 
gradual. The fact that the tree may thus stand naked for some 
time forms the principal objection to its usefulness as a shade for 
cacao, whilst the abundance of mulch formed by its leaves is a 
point in favour of its planting. 
“On fertile cultivated land Castilloa is a surface feeder, and 
develops very heavy roots, which run far, without however forming 
a dense system, as is the case with Hevea. When manure is dug 
down for the benefit of the cacao trees, the roots of both cacao and 
rubber develop equally well in it, very differently from what is the 
case when manure is dug into land planted with bananas and cacao, 
in which case the banana roots grow rapidly and densely into the 
manure to the exclusion of the cacao roots. It would appear that 
the roots of cacao and Castilloa elastica agree well in the same soil. 
The facts that the crop of rubber removes practically nothing 
