Histologically, family Convolvulaceae is characterised by the presence of successive cambia, medullary (internal/intraxylary) and interxylary phloem in majority of the species, whereas some of the members are devoid of successive cambia and medullary bundles. The present study on Argyreia nervosa (Burm. f.) Bojer showed the presence of medullary bundles while internal phloem was absent during the primary growth. As the secondary growth progressed, successive cambia initiated from the pericyclic parenchyma. Development of medullary bundles began along with the regular protoxylem and protophloem while formation of intraxylary phloem was observed only after the initiation of secondary growth. Medullary/intraxylary sieve elements began to develop from the marginal pith cells. In thick stems, small segments of internal cambium initiated between the protoxylem and internal phloem. This internal cambium was functionally unidirectional and produced internal phloem centripetally. Developmental particulars are described in details along with its significance.