CONDITIONING EFFECTS BY NEIGHBORS ON THE GROWTH AND FORM OF TRIFOLIUM-REPENS

As an intact clone (one genotype) of Trifolium repens (white clover) g rows through a sward, parts of the stolon decay and fragments (ramets) are transplanted into different microenvironments. This common garden study was done to assess the impact this placement has on further dev elopment and growth of the new ramets. Genets of T. repens were sample d from each of four origins: from areas in an old pasture dominated by Dactylis glomerata, Holcus lanatus, and Lolium perenne, and from seed . Trifolium from each origin was transplanted into each of three grass beds (Dactylis, Holcus, and Lolium) with three replicates. Cuttings w ere taken annually for 4 years from all the clovers, transplanted into pots, grown for 10-15 weeks, and a number of morphological characters were measured. There was little indication that individuals of Trifol ium grow best in their ''home'' neighborhoods. Most variation in the d ata was the result of within-genet variation, i.e., phenotypic plastic ity, a response assuring survival in environments that vary over time and space. The effects of grass neighbors on Trifolium is mainly expre ssed as size differences and the effect of origins and genets mainly a s differences in shape. The latter is due, in part at least, to differ ent growth rates of parts relative to each other, the former to all gr owth rates being modified in a similar fashion. Because origins and ge nets have a longer history than treatments, these results argue for an evolutionary sequence of first size followed by shape differences.