Panarctic Flora

641025 Potentilla safronovae Jurtz. & Soják

Geography: Circumpolar?: NOR? RFE CAN GRL.

Notes: Elven and Murray: There were large differences in opinions concerning the taxa of sect. Niveae initially in the Checklist process between Yurtsev (following Soják) on one side and Aiken, Elven, Eriksen, and Murray on the other. The account below is a consensus or compromise solution on most issues.

The few arctic taxa of this relationship investigated for their reproductive system - Potentilla arenosa s. lat., P. insularis (see under sect. X Rubricaules above), and P. nivea s. lat. - have predominant agamospermy but some sexual seed set. Hybridization and proliferation of hybrid biotypes is documented in a few cases but is probable in several others. Several of the prerequisites of the model of Soják and Yurtsev for evolution in Potentilla are therefore present: (1) Mixture of sexual and asexual seed production, the latter stimulated by pollen from other species (pseudogamy, see Nyléhn and Hamre 2002). (2) Hybridization between basal species where the major part of the seed-set of a mother plant is agamic, cloning the mother, a small portion is hybridogeneous. (3) Agamic propagation of the hybrid biotypes, sometimes into large populations and happening over fairly large areas. And, (4) occasional back-crossing because the assumed hybrid biotypes are not obligately agamic either.

As stated in the introduction to the genus, the principal difference is in how to handle taxonomy and apply nomenclature in such situations. Soják and Yurtsev have tried to identify (all) such biotypes, to describe and name them formally based on assumed parental combinations, and to support (testable) hypotheses about their origin. We suspect that hybridization and formation of biotypes in many cases is too frequent and too complicated for a formal identification and naming of each and every biotype. In our view (again), hybrid species should be recognized only when they have attained a morphological consistency, an independence from their presumed parents, and a consistent or at least explainable range, and their assumed parentage should be supported by evidence additional to intermediacy in morphological features. Even if we now accept the majority of the proposed taxa, we do not fully agree on all the hypotheses about their origins.

We all now accept sect. Niveae with a P. uniflora aggregate with at least five species, a P. nivea aggregate with 3-5 species, and a P. gorodkovii aggregate of assumed hybrid species developed from crosses between species of the P. uniflora aggregate with species of the P. nivea aggregate. For the variation in northwestern North America, see Elven and Murray (2008a, 2008c) and Ertter et al. (2011). Parts of the variation in sect. Niveae overlap with that in the hybrid sect. X Rubricaules (see above).