Zygostates lunata, SEM and LM. (A) Habit of flower with yellow elaiophores symmetrically located upon labellar callus. (B) Tuft of yellow elaiophore hairs coated with secretion. (C) Elaiophore hairs, at bud stage, located on the callus. (D) Lipids on the surface of elaiophore hairs (asterisks), stained with Sudan III. (E) Elaiophore hairs with secretory residues on the surface of cell walls. (F) Yellow-green secretion both within and on the surface of secretory hairs, following staining with auramine O. (G) Grey lipid droplets in secretory hairs stained with methylene blue–azure II. (H) Staining with PAS reveals the presence of starch in the plastids of both secretory hairs and parenchyma cells (arrows). Scale bars: (A) = 1 mm; (B) = 0·5 mm; (C) = 0·4 mm; (D, G, H) = 50 µm; (E) = 90 µm; (F) = 20 µm. See Fig. 1 for abbreviations.