Fenestraria rhopalophylla: Baby Toes
The adaptations developed by certain plants are sometimes truly fantastic. Perhaps the most remarkable method of adapting to excessive sun is by remaining underground and having the light affect the leaves not from outside but from the inside. How is this achieved? The plant’s leaf tips, the only parts emerging above the surface, are blunt and furnished with translucent panes or ‘windows’ through which the light penetrates to the colourless tissues inside and is dispersed onto the layer of cells containing chlorophyll that line the walls of the ‘light shaft’.
This phenomenon may be found in many species, growing chiefly in South Africa but belonging to different families. Window plants, as they are called, include even the South American peperomias (only a few species) that have several slit- or dot-like translucent ‘windows’ in the thick skin covering the leaves. The method of light dispersal is the same.
Window plants are inhabitants of sun-baked, stony plains. As has already been said they grow underground and several ‘windows’ are all that can be seen on the surface.
In cultivation, where it is impossible to provide them with even a fraction of the light intensity to which they are exposed in the wild, they grow normally above ground.
Fenestraria rhopalophylla is a window plant and is even named thus in Latin (fenestra = window). It grows together with another species of the same genus in South Africa. It forms a ground rosette of 5-cm-(2-in-) long leaves and the, which appear in September or October, are amazingly large – about 5 cm (2 in) in diameter. The other species, F. aurantiaca, has even larger flowers, about 7 cm (2-¾ in) across and coloured golden orange.
Fenestraria should be grown in a very porousbut one that contains ample nutrients, such as John Innes potting compost No. 1 with extra sand added. It is readily propagated from seed, developing into flower-bearing plants in about two or three years.