Comparative morphological and anatomical traits of Adenia lobata (Jacq) Engl. and Adenia cissampeloides (Planch. ex Benth.) Harms. (Passifloraceae)

Comparative morph-anatomical studies of leaf, stem, and tendril were carried out on two Adenia species to enhance the delimitation of the species. The Adenia species have alternate phyllotaxy, simple leaf, glands at the base of their petioles, hypostomatic, similar stomata types, solitary crystal, similar vascular bundle type, tanniferous cells, and dorsiventral leaves. Both species have tetracytic and anomocytic stomata in addition A. lobata had paracytic, and anisocytic stomata. Mucilaginous cells or cavities occurred in the petiole, leaf lamina, midrib, stem, and the tendril of A. cissampeloides but were only observed in the tendril and upper epidermis of A. lobata. The mucilaginous and tanniferous cells were more abundant in A. cissampeloides compared to A. lobata and could account for the reason why A. cissampeloides is used as fish poison. The sclereids in A. cissampeloides are surrounded by lignified cells while the ones in A. lobata do not have such feature. Also, xylem cells in the A. cissampeloides tendril are thicker compared to A. lobata. This could be attributed to the fact that the fruits in A. cissampeloides are directly attached to the tendril. The outline and number of vascular bundles in the midrib and petiole differed among the two species. In A. lobata, the ridge averaged 130 µm thick and 73.76 µm in A. cissampeloides. The analysed characteristics are valuable in the delimitation of these Adenia species.