Figure 2
Extrafloral nectary ontogeny in V. adenantha . (A) View of an inflorescence globose secondary axis bearing 2 flowers that have set fruit and 1-7 extrafloral nectaries (EFNs). (B) Transverse section of an inflorescence secondary axis with a bud (f) covered by a tectrix bract (b) and bracteoles (α, β) and 4 nectaries in different stages (s1, stage 1; s2, stage 2; s3, stage 3; s4, stage 4). (C-H): longitudinal sections of an EFN. (C) Stage 1: Tectrix bract (b) protecting a primordium, developing ring (r) and procambial bands (pb). (D) Stage 2: α and β bracteoles (α, β) with a glandular tricome (g), bud with two calix lobes (k), abscission zone (a), surrounded by the ring with cuticle (cu). (E-F) Section of the basal part of an EFN showing phloem cells (ph) and xylem cells (x). (G) Stage 3. The mature nectary stained with safranin-fast green, exhibiting the ring and the central cells (cc) with secretion (s) among them. (H) Stage 3. Detail of the ring stained with toluidine blue, with highly dense epidermal cells and parenchyma cells with vacuoles (v) filled with dense content. Scale bars: (A) = 7.5 mm, (B-D) = 4 μm, (E, F) =5 μm, G = 100 μm; H = 40 μm.