Panarctic Flora

641017 Potentilla aff. uschakovii

• Potentilla rubricaulis auct., non Lehm. (1830).

Geography: North American (NW): CAN.

Notes: Elven, Murray, and Aiken: This taxon, whatever its name, is the one which usually has been called Potentilla rubricaulus and is one of the major Potentillas of the Canadian Arctic Archipelago (e.g., Porsild 1955, 1957; Porsild & Cody 1980). It has the same putative parentage as P. uschakovii (P. pulchella x subvahliana) but combines features of the assumed parents in a very different way. It differs from P. uschakovii most evidently in regularly digitate or semi-digitate leaves and few, large flowers. This group of plants is well vouchered from Banks, Victoria, Prince Patrick, and Melville islands and perhaps also from the southern islands and peninsulas farther east (Porsild 1957; Porsild and Cody 1980). In these islands it is a major constituent of the Potentilla flora. The plants form large and consistent populations. They are more regularly semidigitate, more silky, and taller and more large-flowered but less rich-flowered than those on the northeastern islands (P. pedersenii). They share with P. subvahliana the compact tussocks with columnar structures made up by many generations of entire withered leaves, and with P. pulchella other features. The combination P. pulchella x P. subvahliana is the most probable, and geographically the only possible, if this plant has a hybrid origin. Whether to include it under the name P. uschakovii will depend on morphological similarity with the Wrangel Island plant. They have not yet been effectively compared but there are many differences in the descriptions. We provisionally enter it as un-named instead of coining a new name before it is better investigated.