Further Investigations into the Physiological Relationship Between an Epiphyllous Liverwort and its Host Leaves

Abstract

Experiments were carried out to investigate the physiological relationship between an epiphyllous liverwort, Radula flaccida Lbg. et G., and its host leaves. The osmotic potential of the epiphylla cell sap (-30 to -35 bar) was found to be much lower than that of the host cells (-10 to -12 bar). There is therefore a good physiological basis for the movement of water from the host leaves to the epiphylla. The amount of light incident on the host leaf which is intercepted by even the heaviest epiphylla colony investigated was less than 2 per cent and this was found to produce no measurable difference between the chlorophyll contents of epiphylla-colonized and uncolonized parts of the host leaf. 14C02 light fixation products were found not to move between the host leaf and the epiphylla in either direction. It is concluded that the dependence (parasitism) of R. flaccida on its host leaves is partial and does not include the derivation of organic food substances.