Figure 4

Light micrographs (LM) showing midrib, mesophyll and secretory cavities of U. molinae. (A) Detail of midrib showing developed adaxial phloem partition, incurved margins of the phloem and discontinuous fibres. (B) Transverse section of the leaf showing cells with idioblasts containing druses (calcium oxalate crystals) below the epidermis. (C) Transverse section of the leaf showing a secretory cavity and epithelial cells on the abaxial surface close to the leaf margin. (D) Early developmental stage of secretory cavity showing epithelial cells in formation. (E) Secretory cavity with eight epithelial cells in formation in young leaves. (F) Freehand section showing secretory cavity on the abaxial side of the leaf. Histochemical reaction indicates lipophilic compounds in the epithelial cells after testing with Sudan IV (orange colour). cr, crystals (druses). Arrows: internal phloem. Scale bars = 100 μm (A-C,E-F) and 10 μm (D).