Ontogeny of Tendrils in Antigonon leptopus H. & Arn.

In Antigonon leptopus the main tendrillar and axillary branch is a modified inflorescence axis. It usually bears 6–7 lateral bracts out of which 3–4 lower ones are small and leaf-like while the upper 2–3 are tendrillar; 2–3 tendrils are also present at its terminal end. The vegetative shoot apex shows a single layer of tunica and an inner mass of corpus without any cytohistological zonation. The earliest axillary bud or tendril meristem arises at the second node and it elongates due to rib meristem activity. The bract primordia arise in an acropetal succession. The initiation of the bract-tendril and the leafy bract is similar. In the development of the bract-tendril, marginal meristem activity is absent or reduced and the differentiation of the apical and subapical initials is absent. The terminal bract-tendrils arise as lateral appendages and the residuum of the apical meristem of the main axillary tendril persists for some time. In the flowering period the floral buds arise in the axils of the bracts and bract-tendrils. No flowers are present in the axils of terminal bract-tendrils.