Panarctic Flora

420208 Cerastium beeringianum Cham. & Schltdl.

• Cham. & Schltdl., Linnaea 1: 62 (1826). Holotype (B)?: Alaska: "Sin. Kotzebue" Kotzebue Sound, 1816, leg. Chamisso isotype? in LE. See notes below for possible implications of the type.

2n= 72 (4x). - Siberia (N), Far East (N), Alaska, Canada. - Numerous reports, one from Wrangel Island for subsp. bialynickii ("Arctic Dwarf", Zhukova 1969).
Some reports from East Chukotka and Alaska are probably referable to var. grandiflorum.

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

Notes: Brysting, Petrovsky, and Elven: Cerastium beeringianum differs in several characters from the possibly closely related C. arcticum and even more from the probably more distantly related C. alpinum. These differences are seen also in the Canadian Arctic where all three species meet. At least three morphological races occur within C. beeringianum, two recognized by Hultén (1956) as var. beeringianum (a) and var. grandiflorum (b) and an "Arctic Dwarf" race (c).

(a) The plant we currently consider as var. beeringianum is comparatively small-flowered and occurs more or less throughout the range of the species. However, it is absent from the northernmost parts where it is replaced by the "Arctic Dwarf", and also from much of the surroundings of the Bering Strait where it is replaced by var. grandiflorum. Note that the species itself was described from the Kotzebue area in western Alaska where var. grandiflorum is the predominant type. A closer study of the type material is needed before varietal names can be assigned with certainty to the races.

(b) The large-flowered var. grandiflorum largely replaces var. beeringianum around the Bering Sea and Strait in South and East Chukotka and in southwestern, western, and central Alaska. Hultén (1956) proposed var. grandiflorum to possibly be result of introgression between C. beeringianum and the North Pacific C. fischerianum, a hypothesis repeated by Morton (2005a). We doubt that hypothesis at least as concerns the mainland Alaskan plants (we have not studied the Aleutian type of var. grandiflorum). Firstly, mainland Alaskan var. grandiflorum is morphologically uniform throughout a large area where C. fischerianum is absent and C. beeringianum s. str. less frequent. Secondly, C. fischerianum is distinguished from C. beeringianum by some characters, e.g., the yellowish, stiff hairs not present in var. grandiflorum. Thirdly, introgression in the strict meaning, i.e., at least partly fertile hybrids that back-cross with and supply genetic material to the parents, is not documented in this group of Cerastium. The results of Brysting et al. (2007b) show that the variation rather is due to complicated combinations of genomes (allopolyploidy). The same basic genomes partake in all races of C. beeringianum without signs of a different parental influence in var. grandiflorum (which was included in Brysting's investigation).

There are indications in annotated herbarium vouchers (LE) that many Russian authors have considered var. grandiflorum as C. beeringianum s. str., whereas they have considered the majority of the material of both var. beeringianum and the "Arctic Dwarf" as C. bialynickii. The first suggestion may be correct as based on the isotype of C. beeringianum present in LE. The last suggestion is less probable.

(c) The high-arctic plant in Siberia, the Russian Far East, and Canada differs in dwarf growth, very compact inflorescences, very small flowers, and with comparatively few transitions to var. beeringianum and none to var. grandiflorum. Morton (2005a) accepted this plant as a species - C. bialynickii - and reported it to be hexaploid (2n = 108). Also in recent Russian literature and in identifications in LE, this plant is named as C. bialynickii and treated as a species. However, the name "bialynickii" is probably not available for it. The syntypes of C. bialynickii (LE!) are not significantly different from what we currently consider as C. beeringianum s. str. For our purpose, this dwarf plant is informally named as an "Arctic Dwarf" race. The assignment of reports of 2n = 108 to this race needs confirmation by review of vouchers. It is more probable that they belong to C. arcticum.

Morton (2005a) synonymized Hultén's C. arcticum var. sordidum with his C. bialynickii. Hultén (1956) interpreted var. sordidum as an introgressive hybrid C. arcticum x regelii, known from Greenland, Svalbard, and Franz Joseph Land. The hybrid hypothesis is probably true for its designated type (S!, see below) but not for the majority of the small-grown to dwarf specimens that Hultén assigned to it. Hultén's introgression hypothesis has largely been refuted. We find little similarity between the majority of the specimens Hultén annotated as var. sordidum and the quite common but probably sterile hybrid. We assign these small plants to C. arcticum (Svalbard, Greenland, northeastern Canada) and C. beeringianum "Arctic Dwarf" (Canada). Morton (2005a) reported his C. bialynickii to be circumpolar but we have not been able to confirm it from the North Atlantic regions.

As to the nomenclature of subspecific taxa, much depends on an investigation of the type of C. beeringianum. If it belongs to the large-flowered Beringian plant, this will be C. beeringianum s. str. and var. grandiflorum Hultén will be a synonym for it. The name subsp. bialynickii is available for the plant currently considered as var. beeringianum and has partly been applied to it in Russian works. The "Arctic Dwarf" is nameless as we are certain that the names C. bialynickii and var. sordidum do not refer to it.

These three races are comparatively major parapatric taxa. Two of them are described as varieties and we enter them at that rank in wait for a more thorough combined morphological and molecular analysis comparable to that done for C. alpinum and C. arcticum-nigrescens. The "Arctic Dwarf" is entered as an unranked taxon.

See also C. regelii and C. jenisejense.