Carex holostoma Drej.
In Nat. Tidsskr. Kjobenjhavn 3: 447. 1841.
Nomenclatural section used by Flora of North America project subgenus Carex, sect. Atratae Christ
Plants with single unbranched stems, or with erect stems arising close together (loosely); more than 15 cm high (usually); (10–)15–20(–30) cm high. Roots pallid-brown. Ground level or underground stems horizontal; rhizomatous, or stoloniferous; elongate. Scales present (on stolons). Aerial stems erect; not filiform (0.8–1.5 mm in diameter, ‘rather stout’. Porsild, 1957); triangular in cross section; glabrous (mostly, but minutely scaberulous on ridges). Leaves mostly basal. Sheaths brown, or reddish (sometimes purplish basal sheaths). Ligules present. Blades straight; linear; flat, or revolute (slightly); glabrous (but minutely scaberulous on midvein and margins).
Flowering stems conspicuously taller than the leaves (usually). Leaf or reduced bract closely associated with the base of the inflorescence present; conspicuous and leaf-like, or reduced, or scale-like; exceeding the inflorescence (rarely), or similar in length to the inflorescence, or shorter than the apex of the inflorescence; 0.5–3.5 cm long; with sheath shorter than the blade. Inflorescence spicate; 1–2.5 cm long; 8–12 mm wide. Pedicels smooth (short, so that the inflorescence is head-like). Inflorescence multispicate (very compact); 2–3 spikes; lateral spikes sessile, or lateral spikes borne on pedicels. Individual spike(s) ascending. Terminal spike wholly staminate. Cladoprophyll present at the base of the peduncle of lateral spikes. Staminate flowers inconspicuous (small, the spike often concealed between the pistillate spikes). Floral scales shorter than the perigynium in fruit, or as long as the perigynium in fruit; brown, or black; with margins, and sometimes mid-vein paler in colour than the adjacent area of the scale (the transparent marginal zone very narrow); ovate; 1.5–2 mm long; 1–1.5 mm wide; glabrous. Perianth absent. Anthers 1.5–2 mm long. Styles thick and short. Stigmas per style 3. Fruit surrounded by a perigynium. Perigynia fused to the apex except for a small aperture through which the style protrudes; obovate; 1.8–2(–2.5) mm long; 1–1.2 mm wide; sessile; erect or ascending; brown, or green; surface dull; glabrous; papillose; appearing nerveless; apices merely conical or rounded. Achenes filling the perigynia; trigonous.
Chromosome information. 2n = 54–60.
Distribution. North American (also known from central W. Greenland, North Iceland and from isolated stations in northernmost Scandinavia and E. Asia. Absent in E. Greenland). Low arctic. Uncommon. Arctic Islands: Baffin (Beekman Peninsula, Kimmirut and Ogac Lake), Southampton (Coral Harbour), Victoria (Surrey Lake; a new collection (CAN 526808) since Porsild (1957) which extends the range considerably. The specimen was annotated as this name by T. Spribille, 1997).
Ecology and habitat. Substrate hummocks, around the margins of ponds, river terraces; imperfectly drained, or on seepage slopes; acidic (a ‘pronounced acidophyte’, (Porsild, 1957) although it has also been reported from a calcareous fen, CAN 259414).
Notes. Polunin (1940) noted that this taxon was frequently classified as a variety of C. norvegica but in the field is entirely distinct and he had seen no transitional forms.
Illustrations. • Herbarium specimen. Note horizontal stems and multispicate inflorescences. Nunavut, Baffin Island, Beekman Peninsula, I. A. McLaren, 64, 7 Aug, 1964. CAN 283973. • Close-up of inflorescence. Close-up of inflorescence showing two female spikes with a single male spike between them. CAN 274109. • Arctic Island distribution.
Cite this publication as: Aiken, S.G., Boles, R.L., and Dallwitz, M.J. 1999 onwards. ‘Cyperaceae of the Canadian Arctic Archipelago: Descriptions, Illustrations, Identification, and Information Retrieval.’ Version: 6th November 2000. http://http://www.mun.ca/biology/delta/arcticf/. Dallwitz (1980) and Dallwitz, Paine and Zurcher (1993, 1995, 2000) should also be cited (see References).
