The non-articulate tissue which occurs in Euphorbiaceae, Apocynaceae, Urticaceae, Asclepiadaceae, consists of long tubes, equivalent to single multinucleate cells, which ramify in all directions throughout the plant.
The trees and plants whose latices furnish caoutchouc in considerable quantity chiefly belong to the natural orders Euphorbiaceae, Urticaceae, Apocynaceae, Asclepiadaceae.
African (Ire or Irai or Lagos) rubber tree, which belongs to the Apocynaceae, a natural order which includes the Landolphia vines as well as other rubber producers.
Of the Apocynaceae the rubber plants are the most important.
This arrangement is characteristic of the flower-buds of Malvaceae and Apocynaceae, and it is also seen in Convolvulaceae and Caryophyllaceae.