Fig. 5

Early stem development in Reichenbachia hirsuta (ontogeny 3). A Initial secondary growth derived from a regular eustele; the dashed ellipse indicates the position of a vascular bundle. B Detail of regular cambium and its derivatives, primary vascular tissues, fibrous pericycle and parenchymatous pericyclic cells (asterisks). C Stem during regular secondary growth, first variant cambium and its derivatives (thick arrow); see details in next Fig. 6A–D. D Regular cambium, secondary xylem and secondary phloem. Scale bars: 50 μm (A–C); 400 μm (D). Arrow (white), companion cell; Arrow (red), sieve-tube element; Asterisks, pericyclic parenchyma cells; ca regular cambium, en endodermis, mz meristematic zone, pe pericyclic fibres, pi pith, pph primary phloem, pxy primary xylem, ra ray, sph secondary phloem, sxy secondary xylem. A–D Stained with toluidine blue