Panarctic Flora

862808-10 The Tephroseris atropurpurea aggregate T. atropurpurea, T. frigida, T. subfrigida

Geography: Asian (N) - amphi-Beringian - North American (NW).

Notes: Murray and Elven: Some authors consider these three species - and also Tephroseris kjellmanii - as races of T. atropurpurea. Tephroseris kjellmanii is morphologically quite different, without any transitions to the others, and we do not consider it part of the aggregate. The three others are morphologically similar, probably closely related, and constitute an aggregate. The taxa are nearly allopatric but with an overlap in the Bering Sea and Straits area. The investigated herbarium material (ALA, LE, O, S) indicates presence of a few intermediates even if we have not yet seen any hybrids in the field. They are mainly reported as diploids (2n = 48, also as more high-ploid in T. frigida). The two alternatives for treatment - three subspecies or three species - are almost equally feasible. We go for species as the simplest solution until hybridization and/or transitions are substantiated.

Tephroseris atropurpurea is mainly arctic Asian and reaches from northeastern European Russia eastwards probably to the Alaskan St. Lawrence Island, perhaps to the Seward Peninsula. The vast majority of the Alaskan plants that has been annotated under this name belong to T. frigida, which is amphi-Beringian and occurs throughout most parts of Chukotka and all of arctic and interior Alaska east to northwestern Canada. It differs from T. atropurpurea in, e.g., an elongated stock with leaves mainly basal (vs. short stock and well-developed stem leaves), in a different composition of the capitula pubescence, and in frequent occurrence of populations without ligules (vs. uniformly ligulate). Tephroseris subfrigida is recorded from oceanic parts of the Russian Far East and has been doubted as an independent species by, e.g., Korobkov (1987b). We are less reluctant to accept it and have seen plants from oceanic (and arctic) southwestern Alaska that we would assign to it.