Fig. 4

Two different ontogenetic trajectories are described in stems with xylem furrowed by phloem wedges in Malpighiaceae. A Ontogeny 1. Stems with phloem wedges that keep a single and continuous cambium (red line). After phloem wedges keep growing, these can be further developed into fissured stems (ontogeny 1a), or the tissue produced by regular cambia adjacent to the wedges may exert mechanical pressure including portions of the wedge (ontogeny 1b), this interxylary phloem keeps reminiscences of the active vascular cambium (black arrows). B Stems with phloem wedges that disrupt the cambium continuity and include portions of phloem wedges, resulting in interxylary phloem (black arrows). Color key: black = pith, blue = secondary phloem, grey = cortex, red = vascular cambium