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Solitary graminoid herb with all branching within leaf sheaths (intravaginal) and forming very dense tussocks, base of subterranean branches forming a densely branched caudex. All leaves basal (also basal leaves on culms). The basal parts covered by dense cylinders of old sheaths, broad and chestnut brown with numerous, marked and slightly raised veins. Culms 1–several from each tussock, 3–10(12) cm, terete or obscurely triangular with 12–15 low ribs.
Leaves erect to spreading, 3–8 cm long, as long as or (in well developed plants) half as long as culms, 0.5–1(2) mm broad, folded (convolute) or rolled inwards (involute), tapering towards apex, sharply serrate in upper parts of their margins, with several indistinct veins, green or often slightly bluish green.
INFLORESCENCE AND FLOWER
Inflorescence a dense aggregation of 3–6(8) spikes (strictly morphologically, they are spike-like, dense panicles), the aggregation in total 8–17 × 4–6 mm. The lowermost spike has a bract 8–13 mm long with a broad, brown hyaline sheath at base, green mid vein and blade, and blade finely serrate in margins; upper bracts reduced to brown hyaline sheaths with green mid veins. Spikes oblong, 6–8 × 2–3 mm, sessile, each with 4–8 spikelets, the uppermost male, the lower ones female. Glumes ovate, subacute, more or less shiny, chestnut brown with broad greenish mid vein and narrow hyaline margins. Perianth absent. Male flowers with 3 stamens. Female flowers enclosed in a perigynium open on one side (a main difference from Carex). Gynoecium of 3 carpels with 3 long stigmas.
Fruit a nut (one-seeded), trigonous, 2–3 mm, pale brown.
Sexual reproduction by seeds; no vegetative reproduction. Adapted to wind pollination with protandry (male flowering predating female flowering). Seed production not surveyed, probably fairly rare.
No adaptation to seed dispersal; nuts (inside perigynia) are probably dispersed passively by water, wind or (occasionally) by birds.
Kobresia simpliciuscula looks like a Carex (and probably also is one, see Comments). The difference in the perigynia, whether they are closed (Carex) or open on one side (Kobresia), is not a useful field character. However, there are no Carex with such dense tussocks with brown sheaths combined with a condensed collection of spikes. The nearest parallel in Carex is C. lachenalii but this species never has such dense tussocks.
Only found in a few, shallow mires in the climatically most favourable parts of Svalbard, all of them on Spitsbergen. In addition, all sites are located in areas with calcareous bedrock.
Thermophilous. Kobresia simpliciuscula has been found in seven sites in Spitsbergen, all within the middle arctic tundra zone and in the clearly or weakly continental sections: in the lowermost part of Gipsdalen (Bünsow Land), at Wordiekammen and in the valley east of Pyramiden (Dickson Land) in the Isfjorden area, in several places on Ossian Sarsfjellet innermost in Kongsfjorden (Haakon VII Land), and at Austfjorden, in Reinsbukkdalen and in Flatøyrdalen on the east side of Wijdefjorden (Ny-Friesland).
The global range is mainly North American, reaching from E Siberia across Russian Far East, North America, Greenland, and to Svalbard (ssp. subholarctica), and W Europe (ssp. simpliciuscula). The affinity of the Svalbard plants is obviously to the west (Greenland).
We accept the Svalbard plants as belonging to ssp. subholarctica, based mainly on the opinions of T.V. Egorova. She assigned the mainland European plants (K. simpliciuscula s. str.) to ssp. simpliciuscula and all other plants to ssp. subholarctica due to assumedly significant differences in the construction of the inflorescence and flowers (see Egorova 1983, 1992). Her arguments for this solution is, regrettably, mainly in Russian (only partly in Latin) and not easily accessible for non-Russians.
Recent phylogenetic studies (Yen & Olmstead 2000 and several subsequent studies) support a merger of Kobresia within Carex or (alternatively, but not really proposed by anyone seriously) an extensive split of Carex into several genera. The open perigynia of Kobresia do not seem to be as evolutionary significant as assumed by pre-molecular scientists.
Egorova, T.V. 1983. Generis Kobresia Willd. (Cyperaceae) florae URSS et conspectus. – Novosti Sistematiki Vysshykh Rastenii 20: 67–85.