Effects of clonal integration on response to sand burial and defoliation by the dune plant Ipomoea pes-caprae (Convolvulaceae)

This study examined the importance of clonal integration on the growth and mortality of a tropical dune plant, Ipomoea pes-caprae L. (Roth), in response to two stresses: sand burial and defoliation. Sand burial and artificial defoliation treatments were applied to one shoot on daughter ramets, some of which were connected to other ramets and some of which were not connected to other ramets. Sand burial significantly enhanced both stem growth and leaf production of the buried shoots, both for connected and unconnected ramets. Defoliation decreased stem growth of shoots other than the defoliated shoot, but only for unburied ramets. Defoliation also had a greater negative effect on growth of other shoots on connected ramets than on unconnected ramets. At the level of the entire ramet, burial stimulated both stem growth and leaf production for connected ramets, but not for unconnected ramets. These results support the hypothesis that physiological integration between ramets mediates the response to both sand burial and defoliation in Ipomoea pes-caprae.