Cytology of the Ecotypes of Diœcious Melandrium dioicum (L. emend.) Coss. & Germ.

Abstract

IN 1942, a tetraploid (2n = 48) plant of the diœcious Melandrium dioicum complex was discovered by D. Löve¹ in a Swedish population. She diagnosed it as “M. crassifolium Fries”², which Turesson³ has considered to be a coastal ecotype of M. dioicum. From herbarium studies of the morphology of adult plants, she further concluded that “M. crassifolium” and M. rubrum subsp. lapponicum Simm.⁴ are synonymous and, as the latter has been regarded by Turesson³ as forming part of the sub-alpine ecotype of M. dioicum, this means that there is no outstanding morphological difference between the ‘coastal’ and ‘sub-alpine’ ecotypes of this species. From a comparison of pollen-sizes in her tetraploid and these ecotypes, she concluded that both the coastal and sub-alpine races are tetraploid.