Performance of two Rhinanthus species under different hydric conditions

Rhinanthus angustifolius and Rhinanthus minor are annual hemiparasitic herbs found in open vegetations. They are closely related, hybridize frequently, and appear to have largely overlapping niches, although some floras report a preference of R. angustifolius for more humid conditions compared to R. minor. We analysed the relative fitness of both species by following their fate from germination to seed production in three different hydric treatments (wet, moist and dry) in a garden experiment. We found that R. angustifolius was either as fit as or fitter than R. minor in all conditions and for all studied parameters, with a slightly higher flower production in R. angustifolius in the wet treatment. Wet conditions had a negative effect on germination and flowering rate, but they increased flower and seed production. These observations show that environmental conditions will influence the composition of mixed Rhinanthus populations.