Characters of trichomes, oil cells and crystals in leaf epidermis of Zingiber shown by light microscopy A, B delicate trichome of Z. ellipticum (A) and Z. densissimum (B) C stout trichome of Z. corallinum D, E detail of delicate trichome of Z. ellipticum (D) and Z. densissimum (E) showing the trichome base (white arrows) F detail of stout trichome of Z. corallinum showing the swollen trichome base (white arrows) G–I oil cells (white arrows) of Z. ellipticum (G), Z. orbiculatum (H) and Z. montanum (I) J, K crystals distributed in the epidermal cells (white arrows) of Z. ellipticum (J) and Z. guangxiense (K) L crystals distributed above the veins (arrow pointing to crystal) of Z. montanum. Scale bars: 50 μm (A, B, C, E, I, K); 20 μm (D, F, G, H, J, L).