Ceara rubber (3Ianihot Gla:iorii).
The Ceara rubber, a tree allied to the tapioca plant, is a native of the dry desert regions of Ceara in Brazil, where there is annually a long spell of drought during which not a drop of rain falls and the soil becomes perfectly dry. Though it fre quently has been planted in the equatorial forest region it has always failed, as a permanently wet climate is quite unsuited for it ; but it might be cultivated with success in sandy regions where there is a fairly heavy rainfall for a few months followed by a spell of absolutely dry weather. Ceara rubber has been but little under cultivation as yet.
It is grown from seed but may be raised from cuttings. The seed is small, rather flat and dark brown. It is borne in a small capsule like that of Para rubber, only much smaller. Because of the hardness of the testa of the seed it germinates slowly, and it is usual to file off the end or grind the angle before planting. The tree grows with fair rapidity, and soon attains a large size in suitable localities. It requires a sandy soil and a dry climate.
It is generally tapped in short cuts and the latex allowed to coagulate on the tree and collected in the form of scrap. However, it can be drawn off in quantity as is Para rubber, and coagulated by means of smoke. The rubber is of a poorer qual ity than Para rubber, but the tree is certainly worth cultivation in countries where the climate is suitable.
Assam rubber (Maus elastica). Pigs. 705-798.
The Assam, or India rubber, is a native of Assam and the Malay region, where it is found growing either as an epiphyte on other trees for part of its life, finally killing its host, or as a rock plant on high precipices. It is well adapted for cultivation in the rain-forests of the equator, but it will also grow farther north than will Para rubber. It is the well-known "rubber plant" of the horticulturist.
Assam rubber can be grown from cuttings, which is the usual method, or from seed. The seed is very small and should be grown in boxes over water, as it may be destroyed by ants. There are 1,000 to 1,200 seeds in an ounce. Cuttings grow rapidly and may be tapped in four years. It grows freely without shade if planted close, but more rapidly under partial shade. The tree sends out aerial roots,
some of which are usually removed, leaving only those which in time may become suitable for tapping. Roots and stems are tapped with a V-shaped cut, made with a gage, and a sharp knife is drawn down the center of each arm of the V.
The latex is more difficult to coagulate than that of Para. It can be coagulated by stirring, or by extracting as much water as possible. One system is to allow it to drop on mats below the tree, where it coagulates and is afterwards removed. The amount of latex produced varies greatly. After heavy tapping the tree requires to be rested for a year or two. The value of this rubber is about the same as that of Central American rubber.
Ire or silk rubber (Funtussia elastics).
Thffi tree grows to a very large size, and takes many years to come to maturity. When of sufficient size and age it produces rubber of excellent quality, but few can wait the time required for it to mature, which may be given at a minimum of twenty years. It might be plan.;ed, however, between quicker-growing kinds, to come in later in case of the exhaustion of earlier-maturing kinds. The tree has attained large size at considerable elevations in the West Indies, where a lower temperature prevails than on the plains. In Trinidad it grows at elevations of 130 to 500 feet above sea level. Funtumia was for merly known as Kiclozia. (Hart.) West African rubber (Landolphia species).
There are several species of this genus which yield rubber of good quality, but which do not respond readily to cultural treatment. They are for the most part high-climbing plants requir ing the support of trees. The latex or rubber coagulates almost as soon as it exudes. It may be formed into rubber by smearing on a smooth sur face. It is related that in Africa native collectors use their arms for this purpose, cutting off the accumulated material when it becomes sufficiently large to inconvenience their working. It may be assumed with some certainty that Landolphias are unlikely to compete with Hevea, Ficus, Castilloa or Manihot. (Hart.) Balata (Mimusops globosa).