Variation in the chromosome number of Parnassia palustris L. in the British Isles

SUMMARY The varieties of Parnassia palustris L. in the British Isles (var. palustris and var. condensata Travis & Wheldon) each have two cytodemes: a diploid (2n= 18) and a tetraploid (2n= 36). The distribution of the cytodemes is loosely correlated with the limits of the Devensian glaciation.