Panarctic Flora

641044 Potentilla tschukotica Jurtz. & V.V. Petrovsky

• Jurtz. & V.V. Petrovsky, Fl. Arct. URSS 9, 1: 320, 217 (1984). Holotype (LE): Russian Far East: West Chukotka, "in montibus Anjuensibus, brachium montis Ionai ad fl. Levyi Jarakvaam", 11. July 1965, leg. B. Yurtsev.

2n= 49 (7x). - Far East (Wrangel Island). - Petrovsky and Zhukova (1981).

Geography: Asian (NE): SIB RFE.

Notes: Elven and Murray: Yurtsev assumed Potentilla tschukotica to be a hybrid species from crosses between P. pulviniformis (or more than one taxon of the P. hyparctica group) and P. uniflora s. lat. Soják (2004) considered it developed from P. pulviniformis x P. uniflora s. str. Yurtsev (PAF proposal) reported it from western Alaska but we consider the specimen behind that report (ALA) to represent a hybrid of uncertain parentage.

Yurtsev: Potentilla tschukotica would be better considered in the P. evestita aggregate with loose wool on the lower side of at least a portion of leaves (greenish-canescent, but the ultrastructure of wool was not identified). The plant is most similar to P. pulviniformis. Similarity extends to the shape and dissection of leaf blade, size of styles, and scarcity (if present) of subsessile glands. The differences are presence of wool (or imperfect wool) on the leaflets below and on the upper part of petioles, leaflets wider, segments shorter and more numerous, and straight hairs softer and longer (1/3 of blade length) etc. The plant is rather common in continental Chukotka, rare in the lower reaches of the Lena River and in Wrangel Island. Only in four localities it occurred with P. pulviniformis. It certainly forms populations. Variability of the taxon may suggest that behind it more than one hybrid combination has taken place.

Eriksen: We do not know anything about any parents.

Elven and Murray: The heterogeneous appearance indicated by Yurtsev and the disjunct occurrences, partly in areas where one or both of the assumed parents are unknown, throws doubts on this as a consistent taxon with the indicated parentage. For comparison, a few plants in the material from arctic Canada (CAN, DAO) seem to originate from hybridization between P. hyparctica and P. subvahliana (in the P. uniflora aggregate) but it would be inappropriate to name these scattered single cases as a taxon.