cultivation because of its very slow growth. It takes twenty 
years to attain full maturity. 
Landolphia oimriensis Beauv., grows in the great tropical 
forest region of western Africa. About half of the Kongo rub- 
ber comes from this vine. A characteristic of this species as yet 
unexplained is that individual plants growing side by side, and 
apparently identical, show wide variations in the amount of 
rubber which they yield, — a fact tending to discourage cultural 
experiments with this species. 
Landolphia Klainei Pierre. Native of the Kongo forests, is 
considered worthy of cultivation in tropical forest regions be- 
cause of its great rapidity of growth. It produces a rose-col- 
ored rubber of high value. 
Landolphia Kirkii Dyer, is the most important rubber-yield- 
ing vine of east Africa, extending from the Portuguese posses- 
sions to Victoria Xyanza. It is the source of "Mozambique" 
rubber, which is worth about 3-4 as much as "Para." 
There are many other species of Landolphias but these are 
economically the most important. 
There are also a number of species of Clitandra and Carpo- 
dinus of greater or less value as rubber-producing plants. 
Root rubber is derived from the roots of various herbaceous 
plants that grow in the open prairies or savannahs in central 
west Africa. The plants are pulled up by the roots, these cut 
off, dried in the sun and the bark peeled. The dried bark 
is pounded in stone mortars until the woody portion 
is pulverized. The rubber is gathered together, pressed into 
balls or cakes and is ready for export. About 1,500 tons of 
root rubber is the average annual crop. It is worth about 60% 
as much as Para. It is derived from the following species of 
plants : 
Landolphia Tliollonii, Dewevre. A woody perennial 6 to 12 
inches high with strong horizontal creeping root stocks extend- 
ing many yards under the surface of the ground. It grows in 
very dry, sandy soils in regions subject to annual prairie fires, 
so that while it is undoubtedly an attractive plant for cultural 
experiments, seeds are not easily obtained. The underground 
rhizomes are very rich in rubber. 
Cnrpodinus chjjlorrhiza K. Schum., and C. gracilis Stapf, 
yield a very elastic brownish-red rubber. They are low shrubs 
2 to 5 feet high, native of dry, desert regions of central west 
Africa, little known botanically, but quite important as sources 
of root-rubber. 
