Floral Nectary Anatomy and Ultrastructure in Mycoheterotrophic Plant, Epipogium aphyllum Sw. (Orchidaceae)

Figure 3

LM observations of tepals. (a) Cross-section of lip with collateral vascular bundles in parenchyma (PAS). (b) Lip part with starch grains in cells on the 3rd day of anthesis stained for polysaccharides insoluble in water (PAS). (c) Central part of furrow from the lip with sunken cells on the top, 3rd day, stained for polysaccharides (PAS). (d) Lip part with starch grains only in abaxial epidermis, 6th day (PAS). (e) Papillate ridges, note the secretion at the top and dense cytoplasm in papillae, the 4th day of anthesis (TBO). (f) Secretion on papillae, 4th day, stained for proteins (ABB). (g) Thin layer of cuticle, 6th day (Auramina O). (h) Cross-section of dorsal sepal with idioblasts with raphides (TBO). (i) Dorsal sepal stained for proteins (ABB). (j) Dorsal sepal with tiny starch grains (PAS) (ad: adaxial (inner) surface, ab: abaxial (outer) surface, c: cuticle, r: raphides, se: secretion, and vb: vascular bundle).