Fig. 6

Development of successive cambia in stems of Reichenbachia hirsuta (ontogeny 3). A Meristematic zone and pericyclic cells that remain parenchymatous (asterisks). B Development of the first variant cambium within the meristematic zone. Arrowheads indicate vessel elements. C First ring of successive cambia with their variant xylem and variant phloem (sc). Initially, the interfascicular cambium (grey arrow) produces mostly phloem axial parenchyma to the outside and xylem fibers to the inner side. D Mature stem showing two rings of successive cambia with conjunctive tissue between them. Scale bars: 100 μm (A–C); 200 μm (D). cph conducting phloem, ct conjunctive tissue, ncph non-conducting phloem, mz meristematic zone, pe pericyclic fibres, pph primary phloem (crushed), ra ray, sc sc1 e sc2, increments of successive cambia, sph secondary phloem, sxy secondary xylem. A–C Stained with toluidine blue. D Stained with astra blue and safranin