Comparative leaf morpho-anatomical studies of two South American species of Cardiospermum (Sapindaceae) with special reference to adaxial domatia

Morphological and anatomical studies of leaves of two closely related Cardiospermum species from South America, C. procumbens and C. pterocarpum, were assayed. Both species have amphistomatic leaves, anomocytic stomata, non-glandular and glandular trichomes, secretory cells present in the epidermis and mesophyll, bifacial structure, and the cuticle showing concentric striae around the stomata. Tunnel-type domatia were found in C. procumbens, at laminar base at the junction of the three principal veins on the adaxial surface. These domatia are interpreted as an apomorphic character for the genus and tribe within the Sapindaceae. In C. pterocarpum domatia are exceptionally present. This is the first record of adaxial domatia in Sapindaceae.