m THE TROPICAL 
be several varieties yieiaing either a poor quality, 
or very little rubber. OE course, coming on the 
plantation in the rainy eeason, when the trees bear 
neither flowers nor seeds, was not exactly calculated 
to facilitate the botanical determination, and I was, 
therefore, compelled to make a fairly close study 
of the morphological and physiological feature of 
the trees. Oa the other hand, had to be borne in 
mind the fact that the whole of our present-day 
information respecting the botanical characteristics 
of the various species of Oast:lloa, and the respect- 
ive value of each of them for cultivation purposes, are 
in quite a hopeless state of confusion. 
According to the usual description Oastilloa elas- 
tica is a tree growing to a height of from 36 to 
54 fee'^jthe trunk at about 3 feet above ground attaining 
to a aiameter of from 24 to 48 inches. The bark 
is smooth and yellow, the wood soft and perishable. 
The leaves are from G to 12 iuches in length, of a 
clear and brilliant green, and their lower side is 
more or less covered with a growth of fine brown 
hairs. Very characteristic of Oastilloa elastica is the 
phenomenon known as dimorphism of the branches 
and which consists in the branches which spring 
from the tree at an angle of 45 degrees at a certain 
point ratlier abruptly taking up a horizontal posi- 
tion. I purposely omit entering here upon a dis- 
cusjion of the flowers aud fruits of 0. elastica as a 
comparison of their characteristics with those pro- 
duced by the tiees at Las Cascadas is at the pre- 
sent moment not possible. Cross, the well-known 
Kew botanist, describes these trees as growing to 
a height of from 160 to 180 feet, with a diameter 
of 5 feet, but he gives no information respecting 
the age of these trees. In all probability these trees 
were an enormous age, to be reckoned by centuries 
rather than tens of years. J. H, Hart, Superinterid jnt 
Royal Botanic Gardens, Trinidad, states that the 
oldest Oastilloa tree, theie is over 75 feet high, aid has 
girth of 4 feet at three feet above ground. Some 
trees 15 years old are from 58 to 6 1 inches in 
a girth. Against these two authorities we posses 
however, the certain information that in Mexico, 
Honduras, Nicaragua, and Ecuador the height of 0. 
elastica varies between 40 and GO feet. 
There are a number o£ other species or varieties of 
Oastilloa, withre.uard to which a considerable amount 
of uncertainty exists. Indeed, only one of these, 
C. tunu Hemsley, is satisfactorily established as a 
distinct and different species, which, moreover, 
although containing a large quantity of latex, 
'yields no india-rubber at all. The C. Blaikhami- 
ana described by Collins as being found in the 
isthmus is considered by several very competent 
authorities not to be a Oastilloa at all, but a Pere- 
bea. I searched everywhere for this species with- 
out ever coming across it, nor had any of the 
various experienced native collectors I questioned ever 
heard of »ny other but the Oaucho tree (0. elastica.) 
Koschay, in a letter which last year appeared in 
the March issue of the " Tropenpflanzor, " describes 
four different Oastilloa as occurring in Costa Kica. 
Of these C. tunu has already been mentioned. Of 
the rubber yielding Oastilloa the best is the one 
possessing a whitish b a-k ; it yields plenty of ex- 
ce'.lent rubber. Another variety has a black bark 
with a rough and irregular surface ; it yields a 
rubber as good as the white variety, but the tree 
is rapidly exhaustei?. A further variety is charac- 
terised by a reddish bark, very thin and fragile ; 
it yields very little latex, but the rubber produced 
of good quality. 
To this must be added that the castilloa of Panama 
appetrj to differ from all other known varieties by 
the occasionally quite enormous size of the leaves. 
Lejves 20 inches in length occur very commonly, 
especially upon young trees. For this reason it has 
been suggested that tho Oastilloa of Panama is a 
separate species. 
Now, as regards the trees at Las Cascada?, while 
iki first eight they certainly strike one as typical 
AGRICULTURIST. [Deo. 1, 1901 
Oastilloa elastica, on closer examination show * 
number of differences which, at any rate in the absenc^ 
of flowers, render the identification of the specie^ 
none too easy. In the first instance, the bark of 
these trees, although very smooth, is certainly neither 
yellow nor white, but a delicate pale pinkish brown. 
The leaves even on the older trees are not very 
great, but still distinctly larger than the leaves 
on grown up trees of 0. elastica in Guatemala, 
Honduras, Nicaragua, and Mexico. The hairy cover- 
ing on the lower side of the leaves is much less 
stiiking, but the young leaf shoot? at the end of 
the branches appear quite as densely haired as those 
of any typical Oastilloa. Also the phenomenon 
above referred to as so characteristic of Caslilloa is 
very strikingly displayed by all the Castilloa trees at 
Las Cascades. 
On the other hand, the only valueless specie of 
castilloa, C. tunu, is absolutely unknown on the 
isthmus, and in ray wandering I have never en- 
countered it.* It is equally certain that the Las 
Cascadas Castilloa is entirely different from Koschay's 
black and red varieties; the appearance of its bark 
could not possibly be described in the terms used 
by Koschay for the latter two trees. In how far 
Koschay's white Castilloa corresponds to the Las 
G.issadas tree is difiicult to say. The bark of the 
latter might, with some appearance of justification, 
be described in Koschay's term as " whitish, " but 
considering that the large silvery patches on it do not 
appear to be the actual colour of the bark, bat 
seem to be due to a lichen, and considering further 
that all the lichen-free portions of the b irk are by 
no means whitish, but as I stated betorr, of a light 
pinkish browu colour, I prefer to adhere to this latter 
description. 
Taking all these points in conj auction it will 
readily be seen that the Las Cascadas rjbber trees 
exhibit all the characteristics of Castilloa elastica 
in regard to the general appearance of the tree, 
the shape of the leaf, the hairy growth on the 
margin of the leaves, their under side, leaf stem, 
and the leaf shootis, as also the phenomenon already 
alluded to as the "dimorphism of the branches." 
I hold these data sufficiently conclusive to demonstrate 
that the Las (^ascadas rubber tree is indeed the 
true Castilloa elastica. The fact that these trees 
produce a good yield of an excellent quality of 
rubber may well be taken a^ contributory evidence 
in the same direction. 
As regards the unquestionable differences of these 
trees from the C. elastica as gecerally described, 
I cannot say that I ascribe any importance to 
them. Castilloa elastica posses e ) such an enormously 
wide geographical distribution— from lat. 6° S. to lat. 
2:'.° N. — it occurs under so ve y greatly varying con- 
ditions of soil, elevation, humiuuy, and temperature 
limits that it would be m;st ext ao diuary if it a<icom. 
modated itself to all these different conditions without, 
at least some morphological change. Indeed, it 
seems highly probable that some of the varying 
staternents regarding the growth of Castilloa elastica 
in different districts may find their explanation in 
the influence upon this tree of different climatic 
conditions. To some extent this may also be, true 
with regard to the various conflicting s'atemeuts 
regarding the yield of rubber obtainable from these 
trees. 
Oa this question of the amount of rubber yielded 
by Oastilloa elastica the information at our disposal 
from numerous sources is charpcteriped by a degree 
o£ discrepancy perfectly app Uing. According to 
Cross a Castilloa of from 18 to 21 inches in diameter 
produces 13 lb. of rubber annu lly, but he asserts 
that certain exceptional trees may yield as much as 
100 lb . Cjllins observed that a 6 year old Castilloa 
posse fing a diameter of 19 inches on b^ing tapped 
in A(.ril, in the dry season furnished 20 gallons of 
* Nor is it at all known, not even by hearsay,, to the 
native rubber collectors on the Isthmus.. 
