Heterochromatin as a cyto-taxonomic character in liverworts:Pellia, RiccardiaandCryptothallus

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Abstract
Application of a Giemsa C-banding technique to the 3 British species of Pellia indicated that the original description of heterochromatin was largely, if not entirely, based on constitutive rather than facultative heterochromatin. The technique had considerable potential in defining liverwort karyotypes more precisely than previously possible, and in assisting cytological comparison of species. The similarity between specimens of P. epiphylla and P. neesiana was greater than the resemblance of either of these species to P. endiviifolia. Chromosome inversion was reported for the 1st time in bryophytes, in P. neesiana, but structural rearrangement, though not necessarily inversion, occurred elsewhere in this genus. Unequal, almost totally euchromatic sex-specific chromosomes were described for a specimen of British R. pinguis. Similarities between the Giemsa C-band patterns of this species and C. mirabilis were not as great as expected. Evidence was presented of unusually early duplication of chromatids in the latter. The reaction of these 5 spp. to the Giemsa C-banding technique revealed a number of difficulties and a lack of precision associated with the terms H- and h-chromosomes. Their use in liverwort cytology should be discontinued.