272 CONTRIBUTIONS FROM THE NATIONAL HERBARIUM. 



The range of C. eostaricana is as yet undetermined, but seems to be included 

 within narrow limits. So far as it is known the species is restricted horizon- 

 tally to the northeastern watershed of Costa Rica and the adjoining districts 

 of Nicaragua and Panama, the climate of which is characterized by perennial 

 rains and almost perpetual dampness of both soil and air. The vertical range 

 is from the sea-level to an altitude of nearly 1,000 meters, with the peculiarity, 

 noticed by all hulcros, a that the rubber contents of the latex and the quality 

 of the product decrease with the distance above the lower level. It has also 

 been observed that the tree does not thrive in soils impregnated with salt 

 water or containing an excess of sand, nor when too directly exposed to strong 

 sea-breezes; lastly, it is never met with in or in close proximity to the coast 

 swamps. 



Castillo eostaricana is par excellence a tree of the virgin forest — ein I'rwald- 

 baum. While its trunks attain there a great length and a considerable girth, 

 it becomes prematurely old in the open, where it never has the healthy appear- 

 ance almost invariably noticed in the lofty forest specimens. Like other trees 

 of the Tropics, the surface of the hark is covered with dense colonies of lichens, 

 the color of which varies with the intensity of the light. 

 This fact has given rise to the belief that there are several 

 varieties of this species, distinguished mainly by the color 

 of the bark and *lso by the correlative fluidity or richness 

 of the latex. Thus the trees that grow in the thickest 

 forest have also the darkest hark and their latex is very 

 thin and easily collected, but contains less rubber ; those 

 which grow in full sun exposure have a light colored hark 

 and a very thick, rapidly coagulating latex. 



> f. Castilla guatemalensis Plttier, sp. now 



fig. 5 0.— Female Plates 35-39. Figures 50, 51. 



Qower of Castilla Medium-sized tree; limbs divaricate and spreading. 



guatemalensls. a, Flowering twigs long, more or less pendulous, densely cov- 



, F f°I e , l i : r,n ! OI> ored witb yeUowiBh, strigose hair, tilled with a thick 'white 



oi pt?iwimn open .,1 . , , , , _ , 



and showing lob- pith ' cIrcled outside by the scars of the stipules. Internodes 



ules. Scale 3. 3 to 7 cm. long. 



LeaA-es congregated at the ends of the younger twigs, 

 petiolate, stipulate, caducous. Petioles 1 to 2.5 cm. long, thick/ densely hairy- 

 strigose. Leaf blades 23 to 46 cm. long, 10 to 18 cm. broad, elliptic, sometimes 

 slightly lyrate, cordate at the base with very narrow sinus, abruptly acuminate, 

 rough and covered with scattered hairs above, tomeutose beneath; midrib and 

 the 19 primary veins inconspicuous and sparsely hairy above, prominent and 

 hairy-tomentose beneath; margin obscurely sinuate, with tufts of hairs between 

 the sinuses. 6 Stipules about 6 cm. long, 2 cm. broad, lanceolate, clasping, longi- 

 tudinally ribbed and tomentose outside, smooth and purplish inside. 



Rubber collectors. 



6 A leaf specimen, collected at the Chocon River Plantation (Department of 

 Izabal, Guatemala) by Sereno Watson, and now in the Gray Herbarium, is 

 remarkable by its petiole measuring 8 cm., by the relatively little developed 

 tomentum on the petiole, midrib, primary veins, and lower face, and by its 

 obscurely dentate margin. The general texture of this leaf is also lighter and 

 it is presumable that it grew in the shade and on a seedling or a young tree. 

 The same applies to Eggcrs 15103, belonging to another species growing in 

 Ecuador, with a petiole nearly 5.5 cm. long and a thin blade with distinctly 

 dentate margin. 



