Most interesting of all the trees was, however, the seringueira (Siphonia elastica), which was extraordinarily plentiful in belts or zones along the courses of rivers in that region. As is well known, the seringueira, which grows wild in the forest there, is one of the most valuable lactiferous plants in the world. Its latex, properly coagulated, forms the best quality of rubber known.
Rubber Tree showing Incisions and the Collar and Tin Cup for the Collection of the Latex.
Coagulating Rubber into a Ball.
There are, of course, many latex-giving plants of the Euphorbiæ, Artocarpæ and Lobeliæ families, but no other are perhaps such abundant givers of latex as the Brazilian seringueira (of the Euphorbiæ family), a tree plentiful not only in Matto Grosso on all the head-waters and courses of the rivers flowing into the Amazon, but also abundant in the Provinces of Para and the Amazon. In less quantities the seringueira is also to be found in Ceará, Rio Grande do Norte and Maranhão.
The seringueira prevailed chiefly near the water, in swampy places, or in places inundated when the river was high. Never was the tree to be found at a distance away from water.
The height of the seringueira varies from 25 ft. to 50 ft. Its diameter is seldom more than 35 in. Its leaf is composed of three elongated leaflets, smooth-edged and complete in themselves. The seed is smooth-skinned, and of a reddish tone. The fruit consists of a well-rounded wooden capsule enclosing three cells which contain white oily almonds not disagreeable to eat. From the almonds an oil of a light red colour, not unlike the colour of old port wine, can be extracted. That oil can be substituted for linseed oil, and has the further advantage of not desiccating so quickly. Mixed with copal and turpentine it gives a handsome varnish. It can be used advantageously in the manufacture of printing-ink and soap. So that every part of the seringueira can be put to some use or other.