Plastid development in distinctively coloured juvenile leaves

summary The juvenile leaves of many tropical and a few temperate plants are translucent and apparently colourless or are white, red or brown in colour rather than green. It is already known that the distinctive colours of the young leaves can result from a delayed increase in chlorophyll content and/or from the masking effects and changing levels of other pigments. The present study deals with the patterns of chloroplast development during leaf growth in Coffea arabica L., Durio zibethinus Murray, Mangifera indica L., Photinia × Fraseri Dress. Red Robin and Theobroma cacao L. Even in very young leaves the mesophyll cells contain chloroplasts, but these are small and few in number. Although conspicuous greening usually takes place only after the leaves are fully expanded, chloroplast development proceeds without interruption throughout leaf growth. The late increase in chlorophyll content is associated with a noticeable increase in the long axes of the chloroplasts and/or their numbers within each cell section. The way in which the overall increase in chloroplast volume per cell is achieved varies between species.