Two laticifer systems in Sapium haematospermum — new records for Euphorbiaceae

Abstract

Sapium haematospermum Müll.Arg. presents two different laticifer systems, distinguishable on the basis of their structure and ontogeny. Although they are both articulated anastomosing laticifers, produced from procambium and (or) ground meristem, they vary in diameter and in the presence or absence of starch. One of them, originating near the promeristem and leaf primordia, is composed of straight, wide laticifers with rod-shaped starch grains, whereas the other one is made up of narrow and sinuous laticifers that arise in expanding organs. The two systems are observed in almost all tissues of the leaf and in the cortical parenchyma and vascular tissue of the stem. Our results show the presence of two different laticifer systems for the first time in Sapium and contradict former reports that described nonarticulated laticifers in this genus. The occurrence of two different laticifer types in the same genus, and indeed the same plant, is extremely rare. The milky latex of the two laticifer systems of S. haematospermum, which consists of terpenoids, fatty acids, phenolic compounds, proteins, and polysaccharides (including mucilage), plays an efficient role in sealing wounds, blocking microorganisms, and avoiding herbivory.