| Abstract: | The development of the vegetative lateral branches in Alstonia scholaris (L.) R. Br. was examined. The overall architecture conforms to Prévost's model and the branches are sympodial complexes of plagiotropic modules. Each module consists of two whorls of 6–11 foliage leaves and a whorl of four scale leaves. The apex is parenchymatized just distal to the scale leaves. Renewal branches grow from buds in the axils of the scale leaves. These large buds are initiated simultaneously with the scale leaves and “use up” a large portion of the original apex. Parenchymatization of the central region of the apex occurs after a period of lateral growth and development that separates and vascularizes the renewal branches. Branch extension occurs sympodially by substitution. More typical buds develop in the axils of the foliage leaves but grow out only in response to injury or pruning. They are smaller than the renewal buds and, unlike them, are delimited by a shell zone during early development. |
