| Polygonum humifusum C. Merk ex K. Koch | |
| Publ. & Syn. | K. Koch, Linnaea 22: 205 (1849). Type: Siberia: Yakutia, "an der Lena", leg. Merk. |
| Notes | Koch's publication of the name Polygonum humifusum predates that of Ledebour, Fl. Ross. 3, 2: 531 (1850). Ledebour's name is, in addition, invalid as a nomen nudum (K. Gandhi in comment). Elven and Murray: The records from Russia have previously been referred to P. humifusum s. str., those from North America to P. caurianum. Löve and Löve (1975a) synonymized P. caurianum with P. humifusum. Russian and Canadian plants are similar in nut shape and surface and in the ochrea. They differ in the perianth. The tepal segments of Asian plants are slightly broader and more overlapping than those of Canadian ones and much less reddish pigmented. Alaskan specimens (ALA) are similar to Asian ones and differ from Canadian ones in paler and broader tepal segments. We want to recognize two races but do not have a name available for the Canadian race. The limit between the races seems to run near the Mackenzie River, not in the Bering Strait as previously assumed. This makes the name P. caurianum and combination made thereon unavailable for a Canadian subspecies. |
| Chromosomes | (1) 40 (4x). - Europe (N). - Karlsson (2000c, secondary report). (2) 60 (6x). - Karlsson (2000c, secondary report). |
| Geography | European (E) - Asian (N/C) - amphi-Beringian - North American (NW). |
| Parent taxon | Polygonum L. |
| Child taxa |
Polygonum humifusum subsp. humifusum Polygonum humifusum subspecies Canadian race |
| PAF ID | 410105 |