Volemitol, sucrose and starch are the principal photosynthetic products of the leafy liverwort Plagiochila asplenioides (L.) Dum. var. major Nees. but the quantitatively most abundant carbohydrates, fructans, do not rapidly incorporate 14C from 14CO2. The limited amount of starch present turns over rapidly but sucrose and especially volemitol do so very slowly and much 14C incorporated during a short pulse remains in these compounds after prolonged periods in the dark (up to 4 months). The liverwort grows under these conditions and 14C incorporated during the pulse passes into insoluble polymers. Loss of chlorophyll is also slow and tissue is photosynthetically viable after such long periods in the dark. Exogenous glucose, fructose and sucrose are absorbed and metabolized in the dark similarly to CO2 in the light except that there is enhanced incorporation into fructans. Exogenous mannitol is absorbed but poorly metabolized.
Results are discussed in relation to polyol- and fructan-containing angiosperms and algae, and from both biochemical and ecological viewpoints.