Panarctic Flora

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500727 Saxifraga rivularis L.

Geography: Amphi-Beringian - North American (N) - amphi-Atlantic - European (N) - Asian (NW).

Notes: Jørgensen and Elven: Morphological and molecular (AFLP) data give support to recognition of Saxifraga rivularis and S. arctolitoralis as different taxa but scarcely at rank of species. They have the same allotetraploid parentage (see above) and we consider them two parapatric subspecies. Kapralov (in comment) reported the Eurasian range of subsp. rivularis to reach east to northwesternmost Siberia. A revision we made of the northern Russian material (LE, 2003) revealed no signs of possible subsp. rivularis or subsp. arctolitoralis between there and Chukotka, a gap of 100 longitude. A similar gap of 60-70 longitude has been assumed in North America. However, very recently plants with the molecular and morphological characteristics of subsp. arctolitoralis have been found eastwards from Beringia in northern Canada and into both western and eastern Greenland, there overlapping with subsp. rivularis (Westergaard et al. in print). The (partial) disjunction seems to be posterior to the origin of the tetraploid (probably in Beringia due to S. bracteata in the parentage) and result either of long-distance dispersal or of vicariance. See Jørgensen et al. (2006).

Higher Taxa