The uniformity of the chloroplasts of all higher plants points out that the optimal form has been found rather early in evolution and has not been changed since. This is different with algae. Many species have just one chloroplast that covers nearly the whole space of the cell's interior. The disc-shaped chloroplast of Mougeotia can be viewed either from above or in profile depending on the amount of light used. Its rotation is an experimentally well-analyzed example of an induced chloroplast movement .
Chromoplasts are red, orange or yellow coloured plastids.
The colour is normally caused by the presence of yellow xantophyll and yellow to red carotinoids . Both compounds do also exist in chloroplasts, but are concealed by chlorophyll. Chlorophyll is broken down much faster than carotinoids as can be seen with the coloured leaves in autumn. Typical chromoplasts cause the orange colour of the carrot, the red colour of the ripe pimento and tomato as well as the colour of numerous flowers. In many cases is the flower's or the leaf's colour caused by the coloured content of the vacuole.