Fig. 4.2-3. Transverse section of leaf of ice plant (Mesembryanthemum). Unlike the leaves of cucumber (Fig. 4.2-1) and birch (Fig. 4.2-2), the collenchyma of these leaves occurs as part of the vascular bundle, just below the phloem. This is a rather large amount of collenchyma, and its bulk may be related to the fact that these leaves are thick, succulent and heavier than those of birch.