| Saxifraga rivularis L. | |
| Publ. & Syn. | L., Sp. Pl.: 404 (1753). Lectotype: Sweden: "Lapland". Linnaeus, Flora Lapponica: t. 2, f. 7. 1737. (Jonsell and Jarvis 2002: 73). See their reasons for rejection of the lectotype (S) Herb. Linn. 174.5, designated by Webb (1987b: 264). |
| 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). |
| Chromosomes | 26 (2x). - Europe (N), Siberia (N), Far East (N), Alaska, Canada, U.S.A.?, Greenland. - Numerous reports, partly for "flexuosa". Diploid in FCM, Jørgensen et al. (2006, Greenland, northeastern, northern, and northwestern Canada, western and southern Alaska, 28 plants from 20 populations, 15 "hyperborea" and 13 "flexuosa"); Guldahl et al. (2005, Svalbard, eastern Greenland, northern Canada, ten plants). Not included: Reports of 2n = 26 (2x) from New Hampshire (Löve and Löve 1961d, 1965, 1966; Löve and Solbrig 1964b) and Iceland (Löve 1970a). The species is not known from Iceland and the report of a diploid from there is almost certainly erroneous. Also the White Mountains in New Hampshire is south of the range accepted for S. hyperborea by, e.g., Porsild and Cody (1980). However, the diploid White Mountains plants are enigmatic and not yet finally assigned to species (see Brouillet and Elvander 2009b: 144). |
| Geography | Amphi-Beringian - North American (N) - amphi-Atlantic - European (N) - Asian (NW). |
| Parent taxon | Saxifraga L. |
| Child taxa |
Saxifraga rivularis subsp. arctolitoralis (Jurtz. & V.V. Petrovsky) M.H. Jørg. & Elven Saxifraga rivularis subsp. rivularis |
| PAF ID | 500727 |