Carex membranacea Hook.
Hooker in Lyon, An attempt to reach Repulse Bay. 195. 1825.
Nomenclatural section used by Flora of North America project subgenus Carex, sect. Vesicariae Carey
Type: Canada, N.W.T., Southampton Island, 1821–1823, W.E. Parry. Holotype: K.
Carex membranopacta L. Bailey
Carex compacta R.Br.
Carex physochlaena Holm
For more detailed and complete synonymy see Ford and Ball (1992).
Plants not caespitose (although sometimes loosely clustered). Plants more than 15 cm high (usually); (10–)15–40(–55) cm high. Roots yellow, or pallid-brown. Ground level or underground stems horizontal; rhizomatous (stout and scaly); elongate. Scales present. Aerial stems erect; not filiform (robust 0.5–1.2(-2.1) mm in diameter, above the uppermost leaf); triangular in cross section (obtusely); scabrous (below the inflorescence). Leaves mostly basal (6–12 per stem). Sheaths collar absent (tightly enveloping the stem; hyaline ventrally; mouth truncate or concave); persisting; brown, or reddish. Ligules present (0.4–3.1(-4.2) mm long, shorter than wide, obtuse at the apex). Blades somewhat curled; linear; flat, or revolute (at the margins), or folded (loosely); glabrous, or scabrous (minutely scaberulous on margins and midvein).
Flowering stems about as high as the leaves, or conspicuously taller than the leaves (usually). Leaf or reduced bract closely associated with the base of the inflorescence present; conspicuous and leaf-like (very variable); exceeding the inflorescence, or similar in length to the inflorescence, or shorter than the apex of the inflorescence; (0.5–)1.5–16(–19) cm long (0.2–3.6(-4.8) mm wide); sheathless. Inflorescence spicate; oblong (each 1–4.5 cm long); 2.5–10(–13) cm long; 15–30 mm wide. Pedicels smooth (or minutely scaberulous, 1–20(-42) mm long). Inflorescence multispicate; 3–5(–6) spikes; lateral spikes borne on pedicels. Individual spike(s) ascending. Terminal spike wholly staminate (9–29 mm long, 1.8–5.2 mm wide; sometimes 1–3 staminate spikes present). Cladoprophyll present at the base of the peduncle of lateral spikes. Staminate flowers conspicuous. Floral scales shorter than the perigynium in fruit, or as long as the perigynium in fruit; black (purplish), or brown; with margins, and sometimes mid-vein paler in colour than the adjacent area of the scale; ovate; 2.2–4.5(–5.5) mm long; 1–1.7(–3) mm wide; glabrous. Perianth absent. Anthers 2.1–3.2 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; elliptic (abruptly contracted into a beak at the apex); (2.2–)2.5–3(–4.1) mm long; 1.3–2.2 mm wide; contracted at the base into a stipe-like structure (0.2–0.9 mm long); reflexed, or spreading at maturity (crowded, forming angles 80–110° with the spike axis); black, or brown; surface glossy; glabrous; tuberculate (slightly); faintly nerved; inflated (slightly); apices beaked with a short beak (0.2–0.8 mm long); apex deeply bidentate (with teeth to 0.3 mm long). Achenes not filling the upper part of the perigynia; trigonous.
Chromosome information. 2n = 74 (76–80).
Distribution. North American (and East Asia, but not Greenland). Arctic. Range in the Canadian Arctic Archipelago wide-spread. Common. Arctic Islands: Baffin, Devon, Ellesmere, and Parry Islands (Bathurst, Melville), Cornwallis, Banks, Victoria, Prince of Wales, Somerset, King William, Southampton, and Coats (and Prince Charles).
Ecology and habitat. Substrate wet meadows, hummocks, around the margins of ponds (and in swales), depressions of low centre polygons, marshes, along streams, river terraces (both lower and raised terraces, and on deltas), lake shores (in peat bogs), tundra, slopes (rocky), ridges, sea shore (on flats and on older beach ridges further inland); imperfectly drained, or on seepage slopes; calcareous; rock, gravel, sand, silt, clay (occasionally), till; with low organic content, or with high organic content, or peat. Occurs in a variety of moist habitats, particularly sedge meadows. It has been noted both around the margins of wet meadows and in the deeper, more saturated areas. Typical associates are Carex aquatilis var. stans, C. scirpoidea, C. atrofusca, or Eriophorum angustifolium. It has also been reported in substrates of widely ranging organic content, including bare wet sand, humic seepage slopes and fairly developed peaty areas.
Notes. Ford and Ball (1992) noted that this species is the most restricted of all the short-beaked taxa in section Vesicariae, being confined primarily to the North American Arctic. It is noticeably absent from Greenland and occurs in Eurasia only in the Chukot Peninsula and Koryakskiy Mountain region of extreme eastern Russia. It is one of the few truly northern species of sedge, being widespread in the Arctic Archipelago and south as far as northern British Columbia, the southern boundary of the Northwest Territories and northern Quebec. Although this species is said to occur in the Churchill, Manitoba region, (Porsild and Cody 1980), no specimen has been found to support this suggestion.
Ford and Ball (1992) noted that anatomically C. saxatilis is indistinguishable from C. membranacea and presented evidence to suggest that this similarity is the result of homoplasy or stasis in anatomical characters rather than an indication of a close evolutionary relationship.
Carex membranacea frequently occurs as a dominant in a wide variety of open, moist habitats that often have a well-developed peat layer. It does not appear to grow in standing water or in shoreline communities.
Illustrations. • Plants in habitat. Plants growing beside small pond, Nunavut, Baffin Island, Iqaluit. Susan Aiken 97–008. CAN. • Close-up of plants. Close-up of plant, apporoximately 20 cm high. Nunavut, Baffin Island, Iqaluit. Susan Aiken 97–008. • Plant in habitat. Isolated plants, about 10 cm high, growing in the water of a seepage slope of rock and silt. Nunavut, Ellesmere Island, Franklin Pierce Bay 79°26'N, 75°38'W. S.G. Aiken 98–032. Photograph by Mollie MacCormac. • Close-up of inflorescence. Multispicate inflorescence with terminal male spike and two pistillate spikes. Nunavut, Baffin Island, Iqaluit. Susan Aiken 97–008, CAN. • Close-up of inflorescence. Multispicate inflorescence with two staminate spikes and one mature pistillate spike with shiny purplish black perigynia. Nunavut, Baffin Island, Iqaluit. Susan Aiken 97–008, CAN. • 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).
