Panarctic Flora

420211 Cerastium regelii Ostenf.

• Ostenf., Skr. Vidensk.-Selsk. Christiania 1909, Math.-Naturvidensk. Kl. 8: 10 (1910). Lectotype (O!): Canada: Nunavut, King William Land, 31. July 1904, leg. Lindström (Jonsell 1996: 6).

Geography: Circumpolar.

Notes: Tolmachev (1971a) and others have accepted two races of Cerastium regelii: a broadly amphi-Beringian subsp. regelii in the northern parts of Siberia, the Russian Far East, and North America, and a broadly amphi-Atlantic subsp. caespitosum in North America, Greenland, and northern Europe including European Russia. Hultén (1958) mapped only the second of these as C. regelii based on his revision of the group (Hultén 1956). Three morphologically different plants are involved:

(a) A strongly pulvinate and glabrous plant is the only one found in the northern parts of the Canadian Arctic Archipelago, in Greenland, Svalbard, Franz Joseph Land, Novaya Zemlya, and Polar Ural. Tolmachev (1971a) treated this plant as subsp. caespitosum, based on Malmgren's C. alpinum var. caespitosum described from Svalbard. This high-arctic plant mainly propagates by bulbils from the shoot apices but flowers profusely with multi-flowered inflorescences late in the season (too late to be observed by the majority of arctic travellers). Its seed reproduction has not been investigated but must be poor. This is the C. regelii of Hultén (1956, 1958) and of nearly all subsequent authors concerned with arctic Canada, Greenland, and Europe. However, their interpretation is in conflict with the type (see below).

(b) A procumbent, straggling, glabrous to subglabrous plant with mostly single flowers at the ends of the shoots replaces the former in the low arctic regions in the southern parts of the Canadian Arctic Archipelago and westwards along the north coast of the Yukon Territory and Alaska and probably in large parts of the northernmost Russian Far East and Siberia west to the Jenisei. This is C. regelii s. str. with type from King William Land in the Canadian Arctic Archipelago. The plant flowers more or less regularly with comparatively large flowers, the size of type (a). The stems, when hairy, have retrorse hairs on the lower internodes, a feature otherwise characteristic of C. beeringianum. Hultén (1956) accordingly described this plant as C. beeringianum var. glabratum. Hultén was not aware of the type behind the name C. regelii, first identified and designated by Jonsell (1996). Tolmachev's (1971a) concept of C. regelii subsp. regelii correctly corresponds to type (b).

(c) A similarly procumbent, but much more densely matted and hairy plant replaces plants (a) and (b) in the southernmost Arctic and the North Boreal in Russia, northwestern Siberia, and in parts of northeastern Siberia and the Russian Far East (Tolmachev 1971a). Also this plant has retrorse hairs on the lower internodes but differs from plant (b) in the characters above and in multi-flowered inflorescences and smaller flowers with much shorter petals. This is the C. jenisejense of Hultén (1956) and Tolmachev (1971a).

Plants (a) and (c) were included in the analyses of Brysting et al. (2007b) and were shown to share the same combination of basal genomes. It is therefore reasonable to consider them within the same species and to apply subspecific rank to the geographically only slightly overlapping plants above. However, plant (c) has not been recombined as a race of C. regelii and is entered below as an unranked taxon jenisejense.

About Cerastium gorodkovianum. - Morton (draft for Flora of North America) recognized C. gorodkovianum Schischk., Fl. URSS 6: 883 (1936), apart from C. regelii but stated that "the 2 taxa may simply be growth forms of the same species". He included in C. gorodkovianum the creeping, almost glabrous and bulbiliferous plants found mainly in the southern and western arctic parts of Canada and Alaska, i.e., Hultén's var. glabratum and our C. regelii s. str. Also Morton was probably unaware that the type behind the name C. regelii belongs to these plants. The name C. gorodkovianum is probably not appropriate for these plant (or for C. regelii as indicated by Morton). The holotype (LE!) of C. gorodkovianum is from northeastern European Russia: the northern Urals, basin of Ljapina River, tributary to N Sosva, upper Manja River, 27. June 1927, leg. V.B. Soczava. The type specimen is very different from the North American plants indicated by Morton as C. gorodkovianum. It is stoloniferous but with a "fontanum" type of leaves, inflorescences, and pubescence. We have no further information about what this plant may be.