Panarctic Flora

330513 Eriophorummedium Andersson

• Andersson, Bot. Not. 1857: 62 (1857). Holotype (S!): Sweden: Lule lappmark, "prope Quickjok", leg. N.J. Andersson (see Fægri 1958: 54; Cayouette 2004: 801).
• Eriophorum rufescens Andersson, Bot. Not. 1857: 79 (1857). Described from northern Sweden. - Eriophorum russeolum subsp. rufescens (Andersson) Hyl., Nordisk Kärlväxtfl. 2: 386, 9 (1966).
• Eriophorum russeolum x E. scheuchzeri.

2n= 58. - Europe (Norway). - Knaben and Engelskjøn (1967).
Not included: A report of 2n = 60 from northeastern Asia (Zhukova 1968) may belong to another plant.

Geography: Amphi-Atlantic - European (N) - Asian (N) - amphi-Beringian.

Notes: Novoselova: Morphological characters of Eriophorum x medium are intermediate between the parents, as is often noted in the literature (Raymond 1954; Tolmachev 1966a; Egorova 1976; Jermy 1980; Kozhevnikov 1988). It has obovoid fruiting heads like E. russeolum, whereas E. scheuchzeri has spherical or half-spherical heads. Scale coloration of E. x medium is very similar to E. scheuchzeri, but shape of scales (lanceolate, pointed) is intermediate between the ovoid, slightly obtuse ones of E. russeolum and the narrowly lanceolate, very long-pointed ones of E. scheuchzeri. Anthers of E. x medium are considerably shorter, (0.8) 0.9-1 (1.2) mm, than those of E. russeolum, (1.5) 2-3 mm, but slightly longer than those of E. scheuchzeri, 0.5-1 mm. The achenes of E. x medium are narrowly obovoid, elongate and glabrate, (2) 2.1-2.5 x 0.6-0.7 mm, and are closer to those of E. scheuchzeri (same shape, 1.9-2 (2.3) x 0.5-0.6 mm) than to those of E. russeolum (obovoid, very rarely elliptical, usually with small spicules at apex, 2-2.2 (2.5) x (0.8) 0.9-1 mm).

Eriophorum x medium is only rarely found in sites where both its presumed parents are present. Numerous authors (Hultén 1927, 1960; Tolmachev 1966a; Kozhevnikov 1988; Timokhina and Bondareva 1990) have reported a very wide range of E. x medium. This might be due to misidentifications of other species of Eriophorum, first of all, non-typical plants of E. russeolum subsp. [russeolum] with light-coloured fruiting heads, darker scales with narrow white margins, shorter anthers and glabrate achenes, and second, E. russeolum subsp. leiocarpum. The main difference between E. x medium and subsp. leiocarpum is achenes narrowly obovoid, elongate, always smooth vs. obovoid, rarely elliptical, very rarely with a few spicules at apex. And third, E. tolmatchevii, the main differences between which and E. x medium are obovoid fruiting heads with entangled bristles vs. widely bell-shaped, rarely almost spherical, with non-tangled, very plain glossy bristles; and scales dark grey, slightly brownish near margins, with very narrow white margins and with prominent red stripes vs. dark grey to black, usually with rather wide white margins, rarely with reddish stripes.

Elven: In northern Norway, E. x medium occurs independent of E. russeolum, rarely in the same mires and more often than E. russeolum in coastal regions. It produces well-developed anthers and full-size fruits and probably disperses independent of the parents. It often appears as a pioneer in disturbed sites (ditches, wet road verges etc.) far away from its putative parents, a strong suggestion that it produces well germinable fruits. It is an acceptable hybrid species rather than merely a hybrid. The synonymization of Andersson's E. rufescens (E. russeolum subsp. rufescens) with this hybrid species is not uniformly supported but is probable. Andersson described his E. rufescens from the same region where Fries and Hartman described their E. russeolum, i.e., northern Sweden ("Lapland"). Ball and Wujek (2002) synonymized E. rufescens with their E. chamissonis.

Elven and Murray: Eriophorum x medium as described above by Novoselova is nearly restricted to the general overlap of the ranges of E. russeolum subsp. russeolum and E. scheuchzeri subsp. scheuchzeri. In its typical form, it is missing from the Arctic in the Russian Far East, Alaska, and northwestern Canada where E. russeolum subsp. leiocarpum overlaps with E. scheuchzeri subsp. arcticum. However, a plant combining some of the features of these two subspecies has been collected repeatedly from several localities on the coastal plain and Arctic Slope of northwestern and northern Alaska (ALA). Combining features are found especially in the shape and color of the scales and the low number of red cells in them, and in anthers of intermediate (or small) lengths. However, the plants have globular flowering (and fruiting) heads and very stout culms, the latter feature distinguishing them from both presumed parents and also from the Russian Far East E. tolmatchevii. Their anthers are at least partly aborting, often retained in the wool until late in the season. The fruiting heads rarely disintegrate and fruits probably abort. These plants are tentatively entered in the distribution table as E. x medium but deviate strongly from the other plants assigned there.

Cayouette (2004) accepted two nothosubspecies of E. x medium, based on hybrids involving different subspecies of E. russeolum. If the northern Beringian plants are confirmed to have originated from E. russeolum subsp. leiocarpum x E. scheuchzeri subsp. arcticum, they would constitute a third nothosubspecies.