Panarctic Flora

500114-16 The Micranthes calycina aggregate M. calycina, M. razshivinii, M. unalaschensis

Geography: Amphi-Beringian.

Notes: Murray and Elven: The aggregate corresponds to subsect. Cuneifoliatae p.p. The three taxa that reach the Arctic are generally similar in morphology but separable in several characters. Micranthes razshivinii is, according to Zhmylev (1990), characterized vs. M. calycina by rhizome long vs. short, leaves spathulate with 5-7 teeth 0.5 mm long vs. rhomboid to fan-shaped with 7-11 teeth 1-3 mm long, and flowering stems and inflorescence branches glabrous vs. more or less pubescent with long hairs. We find these characters diagnostic except for the teeth. Zhmylev (PAF proposal) indicated transitions between M. calycina and M. razshivinii and we have seen a few in the material we have inspected (ALA).

Inspecting material from Alaska and the Yukon Territory, we found M. unalaschensis to be well distinguished from M. calycina by the leaf shape (broadly flabellate), fruit shape (short and broad), and pedicels (stout), in addition to the diagnostic difference in inflorescence hairs (white, long and shaggy, and non-glandular vs. reddish, shorter, and glandular). Some transitions were found, especially north of the range of evident M. unalaschensis. Also Hultén (1968a) indicated transitions between M. calycina and M. unalaschensis. There is no overlap in ranges between M. unalaschensis and M. razshivinii and no transitions either.

The three taxa are parapatric with (few) transitions. We enter them as three species (as did Brouillet and Elvander 2009a) but an equally appropriate solution might be as three races, either of M. calycina or of M. unalaschensis as both were published in the same paper. We can see arguments in this group for a racial treatment (where Brouillet and Elvander 2009a accepted species), whereas we do not see such arguments in the M. nelsoniana group (where Brouillet and Gornall 2007 and Brouillet 2008 applied varieties).