Histological analysis Leaves (completely expanded) were collected at the second node and fixed in 70% FAA (5.0 mL 40% formaldehyde, 90 mL 70% alcohol and 5.0 mL acetic acid) during 72 h (Johansen 1940). After this, the material was transferred into 70% ethanol and dehydrated in an ethanol series. The samples were then embedded in glycol methacrylate (GMA) following the procedure described by Feder and O’Brien (1968) and the manufacturer’s instructions (JB - PolyScience®). After the GMA inclusion, sections were performed with a rotary microtome with steel razor type C, giving a thickness of 7 µm. The cuttings were disposed in the slides and stained with 0.05% toluidine blue for 10 min (O’Brien et al. 1964). Then the slides were washed under tap water for approximately 5 min, dried and mounted in synthetic resin (Entelan®). The pictures were made with digital camera under microscope (Olympus®).