The differentiation of tubulous chromoplasts in developing flowers of Thunbergia alata was studied by ultrastructural, pigment and protein analysis. The way of chromoplast formation in the mesophyll differed from that in the adaxial epidermis. While, in mesophyll cells, the chromoplasts were directly transformed into chromoplasts of the tubular type, characteristic membranes and the tubular reticulum appeared in the adaxial epidermal cells, before the formation of tubules. The disappearance of the photosynthetic apparatus, the formation of membranous structure and the appearance of tubulous were studied. The tubulous chromoplasts contained a 32 kDa protein, an unidentified carotene, and small quantities of lutein and beta-carotene.