The possible methods of lateral thickening in Aloe vera L. and Agave rigida Mill, arc described and illustrated in detail. Primary thickening meristem, vascular cambium and cork cambium all contribute to the thickening of the stem. The vascular cambium is different from that found in dicotyledons and gymnosperms, it produce both vascular tissue and ground tissue (conjunctive tissue) toward the inside and ground parenchyma toward the outside. Some vessel elements arc found in macerated secondary tissue of Aloe vera L.