Kobresia Willd.
Cyperaceae, sedge family.
Sp. Pl. 4, 1: 205. 1805.
Vegetative morphology. Plants herbs; perennial herbs; 3–40 cm high; caespitose (densely); often with a build up of dead sheaths at the base. Roots pallid-brown, or black. Ground-level or under-ground stems not developed horizontally or vertically. Scales absent. Aerial stems erect; filiform, or not filiform; circular or oval in cross-section; glabrous. Leaves in a basal tuft; alternate; existing for a single season or less, or marcescent. Petioles absent. Sheaths persisting; forming a conspicuous build up at the base of the plant; greyish brown, or reddish; collars absent. Ligules present; 0.1–0.4 mm long. Blades 20–200 mm long; 0.2–2 mm wide. Blades straight; linear; circular in cross section, or folded, or caniculate; veins parallel. Blades adaxial surface glabrous. Blades abaxial surface glabrous. Blade margins entire; glabrous.
Reproductive morphology. Plants monoecious. Flowering stems present. Flowering stems about as high as the leaves, or conspicuously taller than the leaves; with leaves, or without leaves. Leaf or reduced bract closely associated with the base of the inflorescence absent. Inflorescence spicate; linear, or oblong, or ovate; 0.8–3 cm long; 2–10 mm wide; a single spike, or multispicate; 2–7 spikes (distinct lateral spikes; each spike made up of 10–20 tiny spike-like panicles "spikelets"); lateral spikes sessile. Individual spike(s) erect, or ascending. Terminal spike staminate at the apex (lateral "spikelets" have male flowers above and female flowers below). Staminate flowers inconspicuous. Floral scales orange brown; with margins the same colour as the body of the scale, or with margins, and sometimes midvein paler in colour than the adjacent area of the scale, or with margins paler than body of scale; acute; ovate, or obovate; 2–6.5 mm long; 1–3 mm wide; glabrous. Perianth absent. Stamens 3. Anthers 1–3 mm long. Carpels syncarpous. Stipes 3 mm long. Styles 1; long and thick. Placentation basal. Fruit surrounded by a perigynium. Perigynia open on one side (a sterile scale enclosing sterile scales, a pistillate and one or more staminate flowers); lanceolate, or broadly ovate; 1.9–5.5 mm long; 0.8–1.8 mm wide; sessile; erect or ascending; brown; membranous; surface dull; glabrous; faintly nerved, or appearing nerveless. Fruit an achene. Fruit 0.6–3.2 mm long; yellowish, or golden brown, or straw coloured; glabrous. Achenes not filling the upper part of the perigynia; lenticular, or trigonous.
Chromosome information. 2n = 52, 56–57, 58, 60, 70–75.
Distribution. Northern hemisphere distribution: circumpolar, or North American. Arctic, or low arctic, or alpine. Range in the Canadian Arctic Archipelago widespread, or limited. Common, or rare.
Notes. The inflorescences of Kobresia cannot be clearly divided
into primary and secondary inflorescences as in most other genera of Cyperaceae.
The proximal part of hte inflorescen usually is composed of bisexual spikelets
arranged on a a simple axis or on a compact panicle. Distally there is a
transition first to spikelets consisting only of a pistiallate flower, then to
staminate flowers subtended by the scale. In species with compound
inflorescences this transition may also occur on the branches. For convenience,
the structures subtended by a scale are all considered to be spikelets even
though stmainate flowers are considered to be simple flower and notto reduced
staminate inflorescence.
1. Perigynia 3.5–5.5 mm; scales 3.5–5 mm,
midvein fading towaqrds the tip...Kobresia sibirica
1. Perigynia
2–3.5 mm; scales 2–3.5 mm, midvien distinct almost to the tip
2.
Inflorescences usually compound (2-)3–8 mm wide; basal sheaths persistent,
dull, usually with remains of blades attached... Kobresia
simplicsiuscula
2. Inflorescenc simple, 2–3 mm wide; basal sheaths
persistent, somewhat glossy, bladeless..Kobresia myosuroides.
Cite this publication as: ‘S.G. Aiken, M.J. Dallwitz, L.L. Consaul, C.L. McJannet, L.J. Gillespie, R.L. Boles, G.W. Argus, J.M. Gillett, P.J. Scott, R. Elven, M.C. LeBlanc, A.K. Brysting and H. Solstad. 1999 onwards. Flora of the Canadian Arctic Archipelago: Descriptions, Illustrations, Identification, and Information Retrieval. Version: 29th April 2003. http://www.mun.ca/biology/delta/arcticf/’. Dallwitz (1980) and Dallwitz, Paine and Zurcher (1993, 1995, 2000) should also be cited (see References).