RUBBER-PRODUCING PLANTS — BCTANICAL 
DESCRIPTION —-PRODWCTIVENESS — 
REGIONS IN WHICH THEY: EXIST 
At the present moment, more than 800 species of rubber- 
producing plants are known to exist, these being distributed 
among the tropical regions of the world. Trees of large size, 
climbing plants and flexible creepers containing the precious 
latex in their branches, trunk and roots, those vegetable growths 
from the double point view of quantity and quality of rubber 
produce have not an equal importance. The species worthy of 
mention belong to four great families: 
1.—Euphorbiacan, Hevea, Micrandra, Manioh. 2.—U]macean, 
Castilloa and Ficus. 3.—Apocynacean, Landolphia, Hancornia, 
Kickxia Carpodium and Clitandra. 4-—Asclepiadaceas, Cal- 
lotropia, Cynanchum. 
The production of rubber in America is principally furnished 
by the heyveas, micandra, manioh, castilloa and hancornia; that 
of Asia; ne the ficus; and that of Africa by the landolphia, 
clitandfa and kickxia. 
In the Amazonian region of Brazil, there exist about 21 
species of heveas; of these the principal is the hevea braziliensis, 
which under.the name of “the Para rubber-tree” deserves to be 
classed in the front rank of all the other lactiferous plants in 
the world. ;;The hevea braziliensis furnishes the most highly 
esteemed quality of rubber, and it is the value of that product 
which determines the prices of all the other species of rubber 
brought on to the market. 
The heveas are powerful trees of from 20 to 30 metres high, 
the trunk which is cylindric in form and. of a light ashy color, 
generally attains a diameter of from 0™80:to 1™20; the branches 
only commence to grow at about 15 metres from the ground. 
The leaves fall in June, but are speedily substituted by others; 
it is during this period that the trees break into flower. 
They: grow in the valley of the Amazon, which within 
Brazil embraces the State of the’ Amazonas, the federal ter- 
ritory of Acre, almost all the State of Para, the Nortn of Matto 
Grosso and of Goyaz and a part of the South of Maranhao, or say 
about 5,000,000 of square kilometres. 
Their habitat as a general rule is a low and warm region 
whose temperature varies between 25° and 30°; without sudden 
changes during the course of the-year and they favor by prefer- 
ence the watery soils, just swampy, damp and even marshy; 
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