283 



THE CULTURE OF THE CENTRAL AMERICAN 



RUBBER TREE, V.* 



{Continued from Bulletin for November.) 



By O. F. Cook, Botanist in charge of Investigations in Tropical 



Agriculture, U. S. Department of Agriculture. 



THE PARA RUBBER TREE IN HUMID LOCALITIES. 

 Following the original publication of James Collins, in 1872, 

 writers on rubber have continued to emphasize the humidity of the 



forests of the Amazon basin. 



The Amazon v alley is remarkablj- for uniformity of teraperatnre and for regular 

 supply of moisture. From June to December is the dry season, and January to 

 May the wet. In the dry season in November there are a few occasional shower?, 

 and during the wet season intervals of fine weather. * * * On the banks are 

 dense moist forests, with caoutchnuc trees interspersed. Dr. Spruce, when at 

 Barra, in December 1850, found that the lains had set in some weeks previous, 

 and from December 10 to the beginning of the following February only a single 

 day occurred without some rain. In February there were six Uiv days ; in March, 

 the most rainy month, only one ; and to April 18 but three days of fine weather. 

 During March the highest tempera ure was 84^° ; many days it failed to reach as 

 high as 80°. 



On the Solimoens. or upper Amazon, the sea breeze is not felt, and it is there- 

 fore more stagnant and snltry. The whole of the country alot'g its banks is 

 covered with one uniform, lofty, impervious, and humid forest. 'I he soil nowhere 

 sandy, but m1 ays either a stiff clay,alluviuin, 'r vegetable nionld. The vegetation 

 is very prolific and the atmosphere densely vaporous. f 



It is difficult to explain why the heavy rains and over-flowed 

 rivers have been dwelt upon with so much persistence and the six 

 months of dry weather left quite out of account, particularly since 

 it has been known from the first that the rubber is obtained in the dry 

 season, and Collins himself states that in the wet season the milk 

 is poor in rubber, or " too aqueous to allow of profitable collection." 



The late Mr. Jenman, government botanist of British Guiana, 

 has described similarly the conditions which he considered typical 



for Hevea sprnccana : 



The water lies in shallow pools between the trees, or is spread in s-heet-, when 

 deeper, over wide spaces of ground, and the surface Sioil generally, especially 

 where this tree most abounds, is hardly more farm or dense than mud. It will 

 give an idea of its character when I say that I wore a pair ui high-laoed-np shoot- 

 ing boots, but with the best care of moving about, and stepping most y on the 

 more sulid soil which is usually found in hillocks around the butts of tr,„e8, or on 

 the fallen bits of wood which stre ch between them, in spite of my care, I was 

 constantly sinking to their tops and over, so that my socks were covered with 

 mud. I am speaking, as I have said, of the wet season of the year, but even in 

 the dry the ground continues in a very moist condition. The land is usually very 

 densely shaded, and in many places, probably in co sequence, produces very little 

 undergrowth 



I have taken the occasion to describe rather fully the character of the land, as 

 it is important that persons contemplating the cultivation of this species of Hevea 

 should be well informed as to the conditiims which prevails in its native haunts.^ 



It is, of course, to be expected that different species of Hevea 

 will be found to prefer different natural conditions but the above 

 account, while well showing what even explorers have been ex- 



♦ Extract from U. S. Department of Agriculture, Bull. No 49, Bureau of Plant 

 Industry, 

 t Collins, J. Keport on the Caoutchouc of Commerce p. 6, 

 t Timehri. 2; 14. 18S.3. 



