Leaf epidermal characters of Zingiber shown by scanning electron microscopy A adaxial epidermis of Z. flavomaculosum showing convex epidermal cells with smooth cuticular membranes B abaxial epidermis of Z. xishuangbannaense showing concave epidermal cells with smooth cuticular membranes C detail of epidermis over the vein in Z. montanum (arrows indicate costal epidermal cells) D stomatal apparatus in Z. flavomaculosum showing guard cells with smooth cuticular membranes E delicate trichomes in Z. xishuangbannaense F stout trichomes with swollen trichome base in Z. corallinum. St: stoma; Gc: guard cell. Scale bars: 10 μm (D); 20 μm (A–C); 100 μm (E, F).