Xylem Conductivity and Anatomical Traits in Diverse Lianas and Small Tree SI)ecies rrom a Tropical Forest or Southwest Mexico

Seven lianas and four small trees collected from a tropical rainforest of Southwest Mexico were studied to relate vessel diameter and vessel frequency to the relative hydraulic conductivity (RC), vulnerability to cavitation and anatomical traits on the secondary xylem. The seven liana species and four small tree species represented ten different families . Two liana species (passiflora ligularis A. Juss. and Vitis tliliifolia Humb. and Bonpl.) showed the highest vessel diameters, RC and vulnerability to cavitation. A small tree (petra volubilis L.) presented the lowest values for vessel diameter, RC and cavitmion. Narrow vessels determined the vessel frequency per mm^2 (-0.58) while wider vessels showed low influence (-0.24). Wider and narrow vessels determined RC and vulnerability to cavitation (r =0.59 to 0.76). Generally, wider vessels presented solitary distribution on the secondary xylem in liana and small tree species and narrow vessels were grouped in clusters. Liana species presented parenchyma in diverse forms, while parenchyma was seanty in the small tree species. The eleven species showed a broad range in RC and vulnerability to cavitation and showed diversity in anatomical traits on secondary xylem indicating that they have different anatomical adaptations with similar growth habit.