Variation in Anthyllis vulneraria L. populations in adjacent regions across acidic and basic soils in Val Piora

Populations of Anthyllis vulneraria ssp. vulneraria and A. vulneraria ssp. vallesiaca are found in close vicinity in Val Piora, where the geological situation changes abruptly between basic and acidic substrates. At three sites with populations of A. vulneraria s. lato, one in basic soil, one in acidic soil, and one in a mixed area, three samples of a total of sixty plants were collected, and flower morphology and physiological activity was determined. Of each population, the number of plants using Braun-Blanquet squares was determined. The frequency and indication values showed that the two subspecies are adapted to different pH values. A. v. ssp. vallesiaca and A. v. ssp. vulneraria are clearly well separated by the red striped keel, the flag dimension, and flower size. In areas where the two species overlap, introgression occurs. The hybrid population consisted of yellow hybrid plants with red keel, yellow plants, and white plants with a red keel. The hybrids are present at a pH value between the ones of the two subspecies. The rapid increase in chlorophyll fluorescence also clearly showed that the two subspecies differed in their kinetics. The values of the hybrid plants (yellow with red keel) were between those of the populations of the two subspecies.