Carex aquatilis Wahlenb. var. stans (Drej.) Boott
Illustr. IV, p. 544. 1867.
Nomenclatural section used by Flora of North America project subgenus Carex, sect. Phacocystis Dumortier
Carex aquatilis subsp. stans (Drej.) Hultén.
Carex stans Drej.
Plants with unbranched stems in loose clusters, or with erect unbranched stems arising close together; more than 15 cm high (rarely less than 15 cm high); (5–)15–30(–40) cm high. Roots pallid-brown. Ground level or underground stems horizontal; rhizomatous, or stoloniferous; elongate. Scales present (light brown and striate). Aerial stems erect, or decumbent (new growth); not filiform; triangular in cross section (hollow in the centre); glabrous, or sparsely hairy (slightly). Leaves mostly basal. Sheaths brown, or reddish (sometimes pale purplish). Ligules present. Blades straight; linear; flat, or revolute, or folded (loosely); septate nodulose (seen on the adaxial surface at 10X); glabrous. Blades adaxial surface glabrous.
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; exceeding the inflorescence; 3–12 cm long; sheathless (the base of the blade may enclose the stem at the node but there is no sheath covering any part of the internode). Inflorescence spicate; (2–)4–10(–12) cm long; 5–15 mm wide. Pedicels smooth. Inflorescence multispicate; 2–5 spikes; 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 conspicuous. Floral scales as long as the perigynium in fruit (green sides of the perigynia visible around the edges of the darker scales); black (purplish); with margins the same colour as the body of the scale; obtuse; 1.5–2 mm long; 0.7–0.9 mm wide; glabrous. Perianth absent. Anthers 2.8–3.2 mm long. Styles slender, not extending beyond the beak. Stigmas per style 2. Fruit surrounded by a perigynium. Perigynia fused to the apex except for a small aperture through which the style protrudes; broadly ovate; 2.2–2.8(–3.2) mm long; 1.2–1.6 mm wide; sessile; erect or ascending; golden brown, or green (blotched); surface glossy; glabrous; papillose; appearing nerveless; with 2 keels; apices beaked with a short beak. Achenes filling the perigynia; lenticular.
Chromosome information. 2n = 76.
Distribution. North American. Arctic. Range in the Canadian Arctic Archipelago wide-spread. Common. Arctic Islands: Baffin, Devon, Ellesmere, Axel Heiberg, Parry Islands, Cornwallis, Banks, Victoria, Prince of Wales, King William, Southampton, and Coats (as well as Prince Charles).
Ecology and habitat. Substrate wet meadows (sometimes below snow banks), hummocks (frost boils), around the margins of ponds, depressions of low centre polygons, marshes (often extensive), along streams (on poorly drained sandy berms; also on the sides of steep gullies), river terraces, lake shores (plants emergent, or in moist areas), tundra, sea shore (in coastal flats, beach ridges and swales, and by the mouths of streams); aquatic, or imperfectly drained, or on seepage slopes; calcareous, or halophytic; rock (carbonate plates, cobble, or bare bedrock), gravel, sand, silt, clay, till (or various combinations of the above); peat (with Sphagnum), or with low organic content (e.g., on bare wet sand), or with high organic content. Often locally dominant in mixed Carex and Eriophorum meadows, often grazed by musk oxen; also found with low Salix shrubs, Arctophila fulva, Dupontia fisherii, and occasionally Sphagnum. These meadows are often grazed by musk oxen. When it grows near the coast, it is usually found in freshwater wetlands (Gadallah and Jefferies, 1995). Although most often a plant of moist places, C. aquatilis var. stans can occasionally be found in dry slopes and plains.
From a broader geologic perspective, this species is found on silty till plains, and alluvial outwash. It has been reported on the sides of drumlins and on colluvium slopes at the bases of cliffs.
Notes. The role of C. aquatilis var. stans in methane efflux from boreal peatlands was studied by Pullman et al. (1995).
In a study of scale-dependent correlations of Arctic vegetation and snow cover in southeastern Victoria Island, Schaefer and Messier (1995) found that C. aquatilis var. stans exhibited positive associations with various measures of snow cover. It is thought that snow cover may reduce the rate of desiccation, protect plants from abrasion, and insulate from low temperatures.
C. aquatilis is a forage species for lesser snow geese (Anser caerulescens). In their study of the nutrient contents of principal forage plants utilized by the geese at La Perouse Bay, Manitoba, Gadallah and Jefferies (1995) show that nutrient content in C. aquatilis is lower than that of C. subspathacea which inhabits salt marshes nearer to the coast. Although the lesser snow goose prefers to forage on C. subspathacea, it will feed on the leaf tips of C. aquatilis during the summer and on the shoot bases and rhizomes in spring and autumn.
Illustrations. • Plants
in habitat. Plants dominant over a small area of a calcareous gravel and
silt, seasonally wet meadow. Nunavut, Ellesmere Island, Scoresby Bay. S.G. Aiken
98–010, CAN. Photograph by Mollie MacCormac. • Close-up of plant. Plants about ten cm. high
with flowering spikes at anthesis. Nunavut, Ellesmere Island, Scoresby Bay. S.G.
Aiken 98–010, CAN. Photograph by Mollie MacCormac. • Close-up of plants. Plants growing on silt
near a pond. Leaf associated with the inflorescence extending beyond it.
Terminal spike male, at anthesis. Lower spikes female. Sachs Harbour, Banks
Island, N.W.T., July 24, 1981, J.M. Gillett 18792, CAN. • Close-up of inflorescence. Terminal spike
with prominent anthers. Base of the spike showing perigynia each with two
stigmas. Nunavut, Ellesmere Island, Scoresby Bay. S.G. Aiken 98–010, CAN.
Photograph by Mollie MacCormac. • Developing inflorescence. Small plant less
than 10 cm high, growing on the edge of an Eriophorum angustifolium meadow.
Developing inflorescences with the stigmas appearing fully extended and
pre-anthesis anthers. N.W.T., Banks Island, Aulavik National Park, 11 July,
1999. Susan Aiken 99–046, CAN. • Close-up of developing inflorescence. Small
plant growing on the edge of an Eriophorum angustifolium meadow. Developing
inflorescences with the stigmas appearing fully extended and pre-anthesis
anthers. N.W.T., Banks Island, Aulavik National Park, 11 July, 1999. Susan Aiken
99–046, CAN. • Close-up of
inflorescence. Terminal spike with prominent anthers. Nunavut, Ellesmere
Island, Scoresby Bay. S.G. Aiken 98–010, CAN. Photograph by Mollie
MacCormac. • Arctic Island
distribution. • Type specimen
of hybrid. Holotype of hybrid Carex x stansalina E. Lepage, C. aquatilis x
C. subspathacea. Nat. Can. 83:150.1956. Nunavut, Southampton Island. H.B.Co.
Post, South Bay, Aug. 25, 1934, Nicholas Polunin s.n. CAN 25083. 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).
