Panarctic Flora

500120 Micranthes hieraciifolia (Waldst. & Kit. ex Willd.) Haw.

• Haw. in Sternb., Revis. Saxifrag., Suppl. 1: 4 (1822). - Saxifraga hieraciifolia Waldst. & Kit. ex Willd., Sp. Pl. 2, 1: 641 (1799). Holotype (B): Central Europe: "Carpath." probably the High Tatras in Slovakia, Herb. Willdenow 839.

2n= 56-120. - Europe (N, C), Siberia (N, S), Asia (C), Far East (N), Alaska, Canada, Greenland. - Numerous reports.
Three levels of chromosome numbers are reported: 2n = 56 and 63 from northeastern Yakutia and West and East Chukotka (about six reports); 2n = 80-82 from central Asia (one report); and 2n = ca. 100-ca. 120 from central and northern mainland Europe, the Caucasus, Svalbard, Taimyr, northern and northeastern Yakutia, southern Siberia, all parts of Chukotka incl. Wrangel Island, Alaska, the Yukon Territory, and Greenland (numerous reports).

Geography: Circumpolar-alpine.

Notes: Zhmylev: Micranthes hieraciifolia shows considerable eco-morphological plasticity not correlated with the chromosome numbers.

Elven and Murray: However, note that all reports of relatively low numbers (2n = 56 or 63) assigned to M. hieraciifolia come from northeastern Asia where an additional race is proposed, whereas all northern plants from non-Beringian regions (in North America, Greenland, Europe, and Asia) are reported with more high-ploid numbers (2n = 100-120, often 112 or ca. 120). Both levels occur in the Beringian regions as do both suggested races.

Malyschev (1994a) commented on this variation, including the ploidy difference, and stated that subsp. longifolia (which they named subsp. czukczorum) is characterized, albeit indistinctly, by narrow (lanceolate) blade on petiole longer than the blade, moderate pubescence on blades and petioles, and some indistinct floral colour differences. Chrtek and Soják (1981), in addition, emphasized smaller size, stem glabrescent in lower parts, and conspicuously dark red petals that are as long as the purplish sepals.

We have surveyed material (ALA, O) from northwestern North America and some from northeastern Asia and find that several characters consistently distinguish subsp. longifolia (subsp. czukczorum) from subsp. hieraciifolia, e.g.: leaves narrow, long-petiolate and acute with little pubescence vs. broader, more short-petiolate and subacute to subobtuse and more pubescent; stems with little pubescence vs. distinctly pubescent; petals purple and as long as sepals vs. pink and much shorter and narrower than sepals; and sepals purple vs. green with purple dots. The inflorescence of subsp. longifolia is more interrupted when fully grown than that of subsp. hieraciifolia but there is overlap in this character. The illustration in Brouillet and Elvander (2009a: 66) shows a clear subsp. longifolia (compare with the illustrations in, e.g., Mossberg and Stenberg 2003 and Elven et al. 2005, showing subsp. hieraciifolia).

These characters distinguish between two easily identifiable plants: the narrowly amphi-Beringian subsp. longifolia and the circumpolar subsp. hieraciifolia, also common and co-occurring with subsp. longifolia in the amphi-Beringian regions. The range of subsp. longifolia is thereby fully enclosed within that of subsp. hieraciifolia, at least in an arctic context. If correspondence between the lower ploidy levels and the morphology of subsp. longifolia is documented (but see Zhmylev's comment above), rank as species might be more appropriate. We have, however, observed a few transitions.

For Saxifraga [Micranthes] xursina Sipliv., see Excluded taxa.