Leaf epidermal characters of Zingiber shown by light microscopy A–C adaxial epidermis of Z. ellipticum (A), Z. montanum (B) and Z. flavomaculosum (C) showing epidermal cells and stomatal apparatus D–F abaxial epidermis of Z. ellipticum (D), Z. montanum (E) and Z. teres (F) showing epidermal cells, costal epidermal cells and stomatal apparatus (arrows indicate to the costal epidermal cells) G–I detail of tetracytic stomatal apparatus on the adaxial epidermis of Z. ellipticum (G), Z. montanum (H) and Z. tuanjuum (I) J–L detail of tetracytic stomatal apparatus in the abaxial epidermis of Z. ellipticum (J), Z. montanum (K) and Z. longiligulatum (L). St: stoma; Gc: guard cell; Lsc: lateral subsidiary cell; Tsc; terminal subsidiary cell. Scale bars: 50 μm (A–F); 20 μm (G–I).