Fig. 5.

Scanning electron micrographs of nectar-exuding tissues in Disa species with secretory epidermis. (A) Petal of D. elegans. (B) Petal of D. longicornu. (C) Spur of D. uniflora. (D) Spur of D. vaginata. (E) Spur cells of D. salteri. (F) Papillae with pronounced cuticular striations in spur tip of D. salteri. (G, H) D. rungweensis. (G) Spur; (H) detail of cuticular blisters. (I–K) D. tenuis. (I) Spur epidermis; (J) overview of spur section showing field of short papillae; (K) Close-up of bulbous papillae. Scale bars: (A, D, F, G, I, K) = 50 μm; (B, C, E) = 100 μm; (H) = 10 μm; (J) = 0·5 mm.