Gen-ecology of capsella bursa-pastoris from an altitudinal transsect in the Alps.

Seeds were collected in wild populations of Capsella bursa-pastoris growing along a cline from low elevations to the high mountain region in Switzerland. Progeny were grown in open field random block experiments and a number of relevant characters was measured. Germination behaviour showed no relationsship to the place of origin and exhibits considerable phenotypic plasticity. Flowering, plant height, rosette diameter and leaf forms displayed genotypic variations that were correlated with altitude. Along the considered altitude gradient phenotypic plasticity was overruled by genetic variation. Later flowering genotypes replaced the earlier flowering genotypes along the topocline which indicates retarded maturity and prolongation of the life cycle at high altitude.