252 CONTRIBUTIONS FROM THE NATIONAL HERBARIUM. 



wing-like formations were particularly conspicuous on the giant speci- 

 mens of G. daguensis observed by the writer between Cordoba and San 

 Jose, in the Dagua Valley ( Cauca-Colombia ) . They are also reported 

 as often present at the base of the trunks of C. costaricana, in the 

 plains of San Carlos." The lateral roots are more or less ramified, 

 and numerous rootlets spread from their lower side into the surround- 

 ing soil. 



trunk. 



There is great diversity in the appearance of the trunk and its rami- 

 fications, according to the species, the exposure, and the climate. The 

 largest size is probably attained by C. daguensis, of which we have 

 seen specimens of no less than 50 meters estimated height and 1.05 

 meters in diameter. The largest individual of 0. lactifiua observed 

 by Mr. Cook measured approximately 25 meters in height, with a 

 diameter of 1.50 meters at the same distance from the ground. 6 In 

 the above-mentioned paper/" Koschny speaks of trees 1 to 1.72 meters 

 in diameter, with a trunk length reaching up to 24 meters, as not un- 

 common in the northern forests of Costa Rica. The more scanty the 

 light the more rapid is also the rise of the trunk and the more prompt 

 the appearance of the permanent branches. In the dark Regenwalder 

 of Central America, namely in Costa Rica and Panama, adult Castilla 

 trees are often met with, the trunks of which shoot up to 15 meters and 

 more, smooth and slender, and supporting only a flat, thinly developed 

 crown. In the open dry districts the branching commonly begins at 

 3 meters or less above the ground and the trees assume a stouter habit. 

 The branches generally form an acute angle with the main axis, but 

 this is not always true, and in C. daguensis, according to notes taken 

 on the spot, they are rather horizontal and spreading. 



TWO FORMS OF BRANCHES. 



In the paper already cited Mr. Cook deals at full length with the 

 pseudobranches and self -pruning of Castilla. so that we do not need to 

 dwell on this subject except to note that those deciduous twigs arise 

 from the axils of the leaves, and can be seen also on permanent 

 branches. Their diameter, at the insertion, is never above 3 cm., and 

 they attain from 3 to 4 meters in length, bearing in distichous rows the 

 very large, showy leaves. 



LEAVES. 



The leaves of all species of Castilla are deciduous and alternate, 

 with a f distichous arrangement that is quite characteristic. They 



"Koschny, T. Die Kultur des Castilloa-Kautschuk. Beiheft zu Tropen- 

 pflanzer, vol. 5, p. 125. (1901.) 



6 Cook, Culture of Central American rubber tree, loe. cit, p. 23. 

 ( ' Koscbny, op. cit., p. 123. 



