Flora of the Canadian Arctic Archipelago
| Flora of the Canadian Arctic Archipelago | |
English: Arctic bluegrass,
French: Pâturin arctique,
Inuktitut: Iviit, ivisuka, ivitsuskaka.
Poaceae, Grass family.
Published in Chlor. Melvill. 30. 1823.
Type: Canada. Melville Island, Mr. J. Edwards on W.E. Parry's first voyage, 1819–1820. Holotype: BM! Isotype: LE.
Vegetative morphology. Plants (7.5–)10–30 cm high; perennial herbs; not caespitose (new branches arising extravaginally, occasionally intravaginally). Only fibrous roots present. Ground level or underground stems horizontal (very occasionally absent); rhizomatous; elongate, or compact; 1 mm wide. Ground level or underground stems scales present; surfaces striate. Aerial stems erect (usually, leafy for approximately half their length). Leaves present; mainly basal; alternate; marcescent. Prophylls 50–70 mm long (in extravaginal branches). Petioles absent. Sheaths present; with the margins fused only in the lower part; glabrous; sheath collars present. Ligules present; (1–)1.5–3.5(–4) mm long; membranous; glabrous; ovate-oblong to transversely oblong. Ligule apices obtuse, or truncate; entire, or erose, or lacerate. Leaves grass-like. Blades 20–60 mm long, 0.8–1.5 mm wide (to 2.5 mm when flat), spreading, folded in bud, linear, flat or folded, veins parallel, midvein conspicuously larger than the lateral veins, bulliform cells in distinct rows on either side of the midvein. Blade adaxial surface hairy. Blade abaxial surface glabrous.
Reproductive morphology. Flowering stems two or more per plant. Flowering stems circular or oval in cross section. Flowering stems with leaves; culm nodes not exposed, or becoming exposed; culm nodes number visible 0–1. Inflorescences paniculate; diffuse; pyramidal (rather open, with 1–3 spikelets characteristically congregated towards the ends of the branches, borne at right angles to the rachis, or drooping slighlty); 2–9.5 cm long; 10–40(–75) mm wide. Inflorescences main axis glabrous, or scabrous (sometimes, near apex). Number of inflorescence branches at lowest node 1–2(–3). Inflorescence primary branches (4–)6–20(–26) mm long; glabrous (usually), or scabrous (sparsely so); with spreading secondary branches. Spikelets disarticulating above the glumes; ovate; 4.4–6.6 mm long; 2.5–4 mm wide. Florets per spikelet (2–)3–4(–6). Two glumes present (glumes unequal, the second almost twice as wide as the first, weakly keeled.). First glume 0.7–0.9(–1) × the length of the second glume (sub-equal to equal in length, but unequal in width); 0.6–0.8 × spikelet length; 3–5 mm long; lanceolate; glabrous; margins glabrous; veins 1–3; apex acuminate (a contrast with P. pratensis subsp. alpigena). Second glume 0.4–0.9 × as long as the spikelet; almost as long as, or longer than, the lowest floret; 3.5–5 mm long. Second glume lanceolate (broadly), or ovate (similar in height to the first glume, but conspicuously wider). Second glume glabrous; veins 3. Rachilla not pronounced between the florets; extending beyond the uppermost floret; internode 1 mm long (approximately); internode glabrous. Callus differentiated (web either a small tuft of curly hairs or well developed); hairs shorter than the floret. Lemma ovate; (3.3–)3.8–5.2 mm long; keeled; surface dull (margins thinner in texture than the body of the lemma); surface hairy; surface with trichomes on and between the veins (longer hairs on the keel and marginal veins, appressed short hairs between the veins, base lanate); veins 5 (not reaching to the apex); apex acute; apex entire; awnless. Palea well developed; 3.5–4.5 mm long; veins hairy (the hairs particularly long towards the middle, and pilose between the veins especially in the lower 1/2, a key distinction between P. arctica and P. pratensis s.l.). Flowers bilaterally symmetrical (zygomorphic). Perianth represented by lodicules. Stamens 3. Anthers 1.2–2.5 mm long. Ovary superior; carpels 3; syncarpous. Ovaries glabrous. Styles 2. Placentation basal. Ovules per ovary 1. Fruit sessile; dry; a caryopsis; 2–2.5 mm long; indehiscent. Seeds 1.
Chromosome information. 2n = 42–88.
2n = 42–88. For the collective species.
2n = 42, 56, 62, 70, 70–74. Zhukova (1968, northeastern Asia);
2n = 56, 60. Zhukova (1969, northeastern Asia);
2n = 56. Sokolovskaya and Probatova (1968, northeastern Asia);
2n = 56. Krogulevich (1971, southern and northern Siberia);
2n = about 56, 70. Krogulevich (1976a, northern Siberia);
2n = 56, 63. Zhukova and Petrovsky (1987b, northeastern Asia);
2n = about 66, about 67, about 68. Hedberg (1967, northern Canada);
2n = about 68, 75. Nannfeldt (1940, Scandinavia);
2n = 68–88. Nygren (1950a, 1950b, Scandinavia);
2n = about 70. Packer and McPherson (1974, northern Alaska);
2n = 70. Armstrong (1937, Canada); Zhukova et al. (1977, northeastern Asia); Löve (1981b, northern Canada);
2n = more than 70. Zhukova and Tikhonova (1971, Chukotka);
2n = about 72. Sokolovskaya and Strelkova (1941, northern Russia);
2n = about 72, about 80. Mosquin and Hayley (1966, northern Canada);
2n = 76. Flovik (1938, Svalbard).
Ploidy levels recorded 6x-11x.
Ecology and habitat. Substrates: wet meadows (where they form raised clumps), hummocks (of Poa arctica plants), along streams, tundra, slopes, ridges, seashores (above tidal influences), dry meadows; imperfectly drained moist areas, solifluction slopes, dry, moderately well-drained areas; rocks, gravel, sand, silt, clay (Bathurst), moss (Melville Peninsula); acidic (granite outcrops), or calcareous (disintegrated limestone). Occurring on moderately to imperfectly drained gravel, on soils adjacent to wetlands, and on raised mossy hummocks in cold wet meadows where it often adopts a tufted form (Gillespie and Boles 2001). It is often an early coloniser of disturbed habitats.
North American distribution. Alaska, Yukon, Northwest Territories Islands, continental Northwest Territories, Nunavut Islands, continental Nunavut, northern Quebec, Labrador. Range in the Canadian Arctic Archipelago widespread. Common. High Arctic. Arctic islands: Baffin, Devon, Ellesmere, Axel Heiberg, Parry islands, Cornwallis, Banks, Victoria, Prince of Wales, Somerset, King William, Southampton (Ellef Ringnes, Resolution and Melville Peninsula).
Northern hemisphere distribution. Circumpolar, or circumboreal (arctic-alpine). Northern Fennoscandian, Kanin–Pechora, Svalbard – Franz Joseph Land, Polar Ural – Novaya Zemlya, Yamal–Gydan, Taimyr – Severnaya Zemlya, Anabar–Olenyok, Kharaulakh, Yana–Kolyma, West Chukotka, Wrangel Island, South Chukotka, East Chukotka, West Alaska, North Alaska – Yukon, Central Canada, Labrador – Hudson Bay, Ellesmere Land – Peary Land, West Greenland, East Greenland.
General notes. A widespread, relatively distinct species, Poa arctica is considered highly polymorphic (Tzvelev 1976; Edmondson 1980). Tzvelev (1976) claimed that it is probably represented in the former Soviet Union by several, still unidentified subspecies with different chromosome numbers. In Svalbard, proliferating and non-proliferating entities are about equally frequent and the non-proliferating ones seem to be highly agamospermic, often with shrivelled anthers and undeveloped pollen (see also Notes for P. arctica subsp. caespitans).
Tzvelev (1976) commented that the rarely found viviparous variety P. arctica var. vivipara Hooker is probably the hybrid between P. arctica × P. pratensis s.l., which is not always distinguishable from some forms of P. pratensis subsp. colpodea (Th. Fr.) Tzvelev. Porsild (1955) suggested that most viviparous High Arctic Poa is best placed in P. arctica as var. vivipara, but unfortunately without explanation. Porsild (1957, 1964) and Porsild and Cody (1980) mapped P. arctica var. vivipara in 18 different localities throughout the Eastern Arctic. We have not been able to verify any of these records. Upon examination of herbarium specimens at CAN and DAO, none were located at CAN, while the several specimens found at DAO were redetermined as P. pratensis subsp. colpodea. Gillespie and Boles (2001) concluded that P. arctica var. vivipara is not present on the Canadian Arctic Islands based on their present understanding of arctic Poa taxa.
Gillespie and Boles (2001) noted that P. arctica is a highly polymorphic species in the Canadian Arctic, and as this variation is far from being discrete morphologically or geographically, they questioned the validity and utility of recognising infraspecific taxa. They agreed with Polunin (1940) that there appears to be so much variation, and plants vary "in such a mixed and baffling manner that I have given up on sorting out the more obvious traits". One of these morphotypes (included here under P. arctica subsp. arctica) is a low cushion or clumped form found in cold wet seepages and meadows at higher elevations in the High Arctic (see image library).
Illustrations. • Habitat: Baffin Island. Foreground grassy sod, where the former whaling station was located, is dominated by a thick Poa arctica sod. Baffin Island, Cumberland Sound, Kekerten Historic Park. 10 August, 2006. Aiken. No Voucher. • Habitat: Baffin Island. Grassy sod of Poa arctica, where the former whaling station was located, is particularly lush in low lying areas. Baffin Island, Cumberland Sound, Kekerten Historic Park. 10 August, 2006. Aiken. No Voucher. • Habitat. Densely clumped plants forming low broad mounds in a hummocky wet meadow at the base of a glacier, about 450 m elevation. Nunavut, Axel Heiberg Island, 80�31.57'N, 92�21.83'W. L.J. Gillespie 6619, L.L. Consaul and R.J. Soreng. CAN. • Close-up of plant. Plants with short flowering culms growing in low mounds. Nunavut, Baffin Island, Nanisivik Airport, 73�02'N, 84�33'W. 9 August, 1999. L.J. Gillespie. 6690, L.L. Consaul and R.J. Soreng. CAN. • Close-up of inflorescence. Inflorescence with 2–3 branches at the lowermost nodes; branches with 1–3 spikelets borne towards the ends of the branches. Aiken and LeBlanc 04–094. CAN 586566. • Laboratory photograph of plant habit. Plant habit showing loose culms developing from rhizomes. Note the inflorescences with few spikelets per branch. Nunavut, Baffin Island. August, 1994. Photograph of plant in laboratory setting by K. Clarkin. • Close-up of inflorescences. Panicles with few slender, more or less pendulous, branches (1–2 per node), and a few small spikelets per branch. Norway, Finnmark, Nesseby, Reppen. July, 1981. Photograph by R. Elven. Voucher at TROM. • Close-up of small inflorescence. Note the delicate inflorescence with one or two spikelets per branch. Nunavut, Baffin Island. August, 1994. Photograph of plant in laboratory setting by K. Clarkin. • Holotype specimen. Melville Island, 1819–1820, Mr. J. Edwards on W.E. Parry's on his first voyage. (Holotype: BM). Other text on label: "Poa arctica R. Br. in Parry, Journ. Voy. Discov. NW Pass. Suppl. 288 (1924)". • Arctic Island Distribution.
This publication is available on the internet (posted May 2011) and on CD-ROM (published in 2007). These versions are identical in content, except that the errata page for CD-ROM is accessible on the main index page of the web version.
Recommended citation for the web-based version of this publication: Aiken, S.G., Dallwitz, M.J., Consaul, L.L., McJannet, C.L., Boles, R.L., Argus, G.W., Gillett, J.M., Scott, P.J., Elven, R., LeBlanc, M.C., Gillespie, L.J., Brysting, A.K., Solstad, H., and Harris, J.G. 2007. Flora of the Canadian Arctic Archipelago: Descriptions, Illustrations, Identification, and Information Retrieval. NRC Research Press, National Research Council of Canada, Ottawa. http://nature.ca/aaflora/data, accessed on DATE.
Recommended citation for the CD-ROM version of this publication: Aiken, S.G., Dallwitz, M.J., Consaul, L.L., McJannet, C.L., Boles, R.L., Argus, G.W., Gillett, J.M., Scott, P.J., Elven, R., LeBlanc, M.C., Gillespie, L.J., Brysting, A.K., Solstad, H., and Harris, J.G. 2007. Flora of the Canadian Arctic Archipelago: Descriptions, Illustrations, Identification, and Information Retrieval. [CD-ROM] NRC Research Press, National Research Council of Canada, Ottawa.
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