XVI International Botanical Congess

Leaf architecture has been investigated in 7 genera and 27 species of the family Tiliaceae. The mature leaves were cleared following the method of Mohan Ram and Nayyar (1978), and characterizations and terminologies of Hickey (1973) were used to determine the characters of the leaf architecture. The whole lamina of the Tiliaceae is more or less symmetrical in all the species studied. The major venation pattern in most of the members investigated is actinodromous, perfect. basal. Pinnate craspedodromous, semicraspedodromous are however, also noticed. Pattern of tertiary veins may be either orthogonal reticulate or percurrent. In all the members of the family the primary and the secondary veins are ornamented with parenchyma bundle sheath. Imperfectly developed areoles are predominant over the developed ones. Areoles may be with or without freely ending ultimate veins. Free vein endings may be with our with tracheids. They are commonly uniseriate in all the Tiliaceae members investigated. The highest venation order of the family is sixth degree and the lowest fourth. Marginal ultimate venation is commonly incomplete, rarely fimbriate or looped. These characters are of taxonomic importance.