Previous work in our laboratory has shown thatCannabis saliva(marijuana) contains water-soluble, high molecular weight components that have extremely potent intraocular pressure (IOP) lowering activity. Aqueous extraction of other plants has now shown that a number of them also contain components with potent IOP lowering activity in rabbits. These include tobacco, cabbage, lettuce, several greens,Senecio anonymus, Erigeron philadelphicus, and several others. Not all plants tested were active, however, indicating that while more ubiquitous than originally thought, these materials are not apparently extractable from all plants. The chemical composition of the active fraction from tobacco was found to be different from that derived fromCannabis sativa.