ENVIRONMENTAL HETEROGENEITY AND CLONAL GROWTH - A STUDY OF THE CAPACITY FOR RECIPROCAL TRANSLOCATION IN GLECHOMA-HEDERACEA L

Clonal fragments of Glechoma hederacea L. (Lamiaceae) were subjected t o environments in which light and nutrients were supplied with a stric tly negative association in space, i.e. when one of these resources wa s in ample supply the other was scarce. Treatments were chosen to simu late environments in which clones grew either within homogeneous condi tions or across patch types (heterogeneous conditions). The hypothesis was tested that reciprocal translocation (i.e. exchange of both nutri ents and assimilates) between connected groups of ramets would increas e biomass production of clones growing under heterogeneous conditions compared to that of clones growing in homogeneous conditions. A cost-b enefit analysis was carried out to test this hypothesis. Results sugge sted that reciprocal translocation did not occur at the structural sca le considered in this experiment; no evidence was found for a signific ant effect on whole clone biomass of assimilate and/or nutrient transl ocation between clone parts experiencing contrasting levels of resourc e supply. It is suggested that predominantly acropetal movement of res ources and the pattern of integrated physiological unit formation in G . hederacea are the main properties responsible for the lack of mutual physiological support between connected clonal fragments growing in d iffering habitat conditions. These properties are expected to promote clonal expansion and the exploitation of new territory, rather than su staining clone parts in sub-optimal patches of habitat for prolonged p eriods of time.