Arctagrostis latifolia (R. Br.) Griseb. subsp. latifolia
Polar grass.
Poaceae, grass family.
Ledeb., Fl. Ross. 4: 434. 1852.
Colpodium latifolium R. Br., Chlor. Melvill. 28. 1823.
Type: Canada. Melville Island, W.E. Parry, 1819–1820. (Holotype: BM! two fragments at LE, Tzvelev 1976).
Arctagrostis latifolia var. longiglumis Polunin, Bull. Natl.
Mus. Canada 92 (Biol. Ser. 24): 48. 1940. Type: Canada. Nunavut: Baffin Island,
Foxe Island, Nettilling Lake, 24 Aug. 1925. J.D. Soper 125636. (Holotype:
CAN! Cotype: BM!).
Arctagrosits latifolia subsp. nahanniensis
A.E. Porsild, Bull. Natl. Mus. Canada 171 (Biol. Ser. 64): 120. 1961. Type:
Canada. N.W.T.: Mackenzie Mountains, Hole-in-wall Lake, lake shore, in sand,
elev. 3800 ft., July 18, 1960. E.W. Arnold 121 (Holotypeastern Canada!).
Colpodium latifolium R. Br.
Vegetative morphology. Plants perennial herbs; 10–95 cm high; not caespitose; stems arising close together or singly (usually producing only a single culm per year in the High Arctic). Ground-level or under-ground stems horizontal; rhizomatous; elongate, or compact; 2–3 mm wide. Scales present; smooth; 8–30 mm long; glabrous. Aerial stems erect; circular or oval in cross-section; glabrous (uppermost culm node condensed in lowest 3rd of plant). Leaves distributed along the stems; alternate; marcescent. Petioles absent. Sheaths with the margins fused only in the lower part; with trichomes; scabrous (seen at magnification 40× on flag leaf sheath; uppermost culm sheath longer than the blade); collars present. Ligules present; 2.5–5 mm long; membranous; glabrous; transversely oblong; apices obtuse (broadly); erose, or lacerate. Blades 6–80 mm long; 2–4 mm wide (when flat). Blades appressed to the stem, or spreading; rolled in bud; linear; flat; veins parallel; midvein similar in size to other veins in the leaf (mid leaf). Blades adaxial surface scabrous. Blades abaxial surface scabrous.
Reproductive morphology. Flowering stems present. Flowering culm nodes becoming exposed (lower sheaths); number visible 0–3. Inflorescence paniculate; dense (in plants growing in cold habitats), or diffuse (branches spreading and inflorescence becoming stiffly pyramidal, when plants grow at warmer sites); linear, or oblong, or lanceolate; 2.5–10(–17) cm long; 8–26 mm wide; main axis glabrous. Number of inflorescence branches at lowest node 5 (or more). Inflorescence primary branches 5–40(–65) mm long; scabrous; with appressed secondary branches (usually), or with spreading secondary branches (in warmer habitats). Spikelets pedicellate (3–15(-40) spikelets per branch); disarticulating above the glumes; laterally compressed; oblong; (3–)4–6 mm long; 1.3–2.4 mm wide. Florets per spikelet 1 (rarely 2). Glumes sub-equal. First glume 0.8–0.9 × the length of the second glume; 0.65–0.85 × spikelet length; 1.8–4.3 mm long; lanceolate; glabrous; margins glabrous; veins 1(–3); apex acute. Second glume 0.4–0.9 × as long as the spikelet; shorter than the lowest floret (usually 1 mm or more shorter than the lemma); lanceolate; 2.3–5 mm long; glabrous; veins (1–)3. Rachilla extending beyond the uppermost floret (usually, rarely terminating in a well-formed or a vestigial floret). Callus differentiated; hairs shorter than the floret. Lemma 3–6 mm long; lanceolate; keeled (thinner in texture towards the apex); surface dull; surface sparsely scabrous (similar to lemma surface); surface with trichomes on and between the veins; veins 3–5 (lateral veins obscure, not reaching to the apex). Lemma apex acute; entire; glabrous; awnless. Palea well developed; 3.7–5.5 mm long; with scabrous veins (similar to the lemma in length, with a single keel at one prominent vein and the second vein faint). Perianth reduced to lodicules. Stamens 3. Anthers 1.8–4 mm long. Gynoecia superior. Carpels syncarpous; 3. Styles 2. Ovules 1. Fruit sessile. Fruit dry; a caryopsis; indehiscent. Fruit 1.7–3 mm long. Seeds 1.
Chromosome information. 2n = 28, 42, 56, and 62. 28
(4x). - Vouchers in LE
42 (6x). - Sokolovskaya (1955,
'suppressed' by Löve and Löve 1975).
56 (8x). -
Holmen (1952 Greenland); Jørgensen et al. (1958 Greenland); Bowden (1960a
North America); Sokolovskaya and Strelkova (1960); Löve and Löve
(1964a); Löve & Ritchie (1966 northern Canada); Hedberg (1967 northern
Canada); Zhukova (1967a north eastern Asia); Johnson and Packer (1968
northwestern Alaska ); Sokolovskaya (1968 northe eastern Asia, Koryak); Packer
and McPherson (1974 northern Alaska); Krogulevich (1976 northern Siberia, 1978
southern and northern Siberia!); Zhukova and Petrovsky (1976 western Chukotka,
1987a north eastern Asia, 2n = 57); Zhukova et al. (1977a north eastern
Asia); Zhukova (1982 north eastern Asia).
62 (c.9x). - Flovik
(1938 Svalbard, a count 'suppressed' by Löve and Löve 1975).
Distribution. Northern hemisphere distribution: circumpolar, or circumboreal. Arctic. Range in the Canadian Arctic Archipelago widespread. Arctic Islands: Baffin, Devon, Ellesmere, Axel Heiberg, Parry Islands, Cornwallis, Banks, Victoria, Prince of Wales, Somerset, King William, Southampton, Coats.
Ecology and habitat. Substrates: wet meadows, hummocks, around the margins of ponds, marshes, along streams (and in old stream beds), river terraces (channels, floodplains or braided flats), tundra, slopes, ridges; imperfectly drained moist areas, or on seepage slopes, or on solifluction slopes, or dry, or moderately well drained areas; calcareous; rocks, gravel, sand, silt, clay (sometimes slumping on slopes), till, moss; with low organic content, or peat (rarely in peat bogs). Habitats: Occurring in a wide range of habitats and exhibiting considerable phenotypic plasticity that appears to reflect the warmth and nutrients available in an environment. This is a circumpolar species that in the eastern Canadian Arctic Islands is most commonly found in the warmer sectors where it is a regular, but generally not abundant, constituent of moderately to imperfectly drained tundra communities, but it is rarely a primary colonizer.
Taxon as an environmental indicator. Culm height in this species appears to be strongly correlated with environmental factors, particularly temperature. Plants growing on the sheltered or sunny side of a rocky outcrop may be conspicuously taller and have more open inflorescences than plants growing in a colder, north facing adjacent microhabitat. How open the inflorescence branching becomes also appears to be related to environmental factors. Plants with larger more spreading inflorescences occur in known thermal oases, for example, an oasis that has been documented by J. Jacobs, Dept. of Geography, Memorial University, at Burwash Bay, Nettilling Lake, Baffin Island.
Notes. The nematode Anguina agrostis Steinbuck infects
spikelets and causes the ovaries to enlarge and become dark purple (Mulvey
1963). Other parts of the infected spikelet become atypical. Specimens with this
infection are conspicuous and have been annotated as forma prolifera or
forma vivipara, but these names have no taxonomic validity.
Porsild
(1964) did not mention var. longiglumis Polunin, that was described from
a thermal oasis on Baffin Island by Polunin (1940), who also described the
species as "an atrocious typus polymorphous". Aiken and Lefkovitch (1990)
studied the genus, documented considerable phenotypic plasticity within the
species, and found only subsp. latifolia on the Arctic Archipelago,
although subsp. arundinacea (Trin.) Tzvelev occurs nearby on the North
American continent. No reason for recognizing var. longiglumis was found.
Ovenden (1986) found Arctagrostis latifolia and Puccinellia
borealis were common on the lake bed of
Illisarvik, the site of a
thermokarst lake that was artificially drained in August 1978. By 1985, the lake
bed was dry in most areas and wind erosion was extensive. The surface material
was either sandy peat or organic lake mud, except along the eastern margin,
where it was sandy. Substrate type appeared to have had little influence on
distributional patterns of the colonizing vegetation. More important factors
were probably erosion, surface wetness, and proximity of the lake-bed margin.
Other widespread species included Senecio congestus, Carex
aquatilis, Descurainia sophioides, Tripleurospermum
maritimum (Matricaria ambigua), Artemisia tilesii,
Arctophila fulva, and Stellaria longipes. Senecio and
Arctophila formed dense stands around the two small residual ponds.
Eroded surfaces have a very scant cover of Descurainia seedlings and
Puccinellia tussocks. Many elements of Illisarvik's flora are common to
other recently disturbed sites near the Arctic coast of northwestern North
America.
Illustrations. • Plant habitat. Plants growing on small island in flood plane of stream on wet, calcareous silt. Nunavut, Ellesmere Island, Scoresby Bay 79°53'N, 71°33'W. Aiken 98–013. Photograph by Mollie MacCormac. • Close-up of inflorescence. Plant approximately 30 cm high, with compact, reddish inflorescensce that has branches with few spikelets and uppermost leaf witht he sheath longer than the blade. Aiken 98–013. CAN. • Close-up of preanthesis inflorescences. Spikelets appressed, inflorescence very narrow prior to anthesis. Nunavut, Ellesmere Island, Scoresby Bay 79°53'N, 71°33'W. Aiken 98–013. Photograph by Mollie MacCormac. • Laboratory photograph. Plants collected in Nunavut, Baffin Island, Iqaluit, Aiken 94–022. (CAN). and photograph by K. Clarkin in Ottawa. • Close-up of inflorescence. Inflorescence at anthesis photograph by K. Clarkin. S.G. Aiken 94–022. (CAN). • Close-up of inflorescence. Inflorescence at anthesis, with purple anthers, approximately 3 mm long, and white, feathery stigmas. Note that the spikelets have a single floret, the second glume is at least 1 mm shorter than the lemma, and that the palea is almost as long as the lemma and folded so that it look similar to the lemma. Photograph by K. Clarkin. Canada. Nunavut, Baffin Island, Iqaluit, Aiken 94–022. (CAN). • Inflorescences. Inflorescences of plants in mire at boreal/arctic transition. Norway: Finnmark, Vardoe, Langbunes. July 1981. Photographed by R.Elven. Voucher in HbTROM. • Inflorescence. Part of panicle. Norway: Finnmark, Vardoe, Langbunes. July 1981. Photographed by R.Elven. Voucher in HbTROM. • Holotype, ssp. nahanniensis. Holotype of taxon described as subspecies nahanniensis. Canada. N.W.T.: Nahanni Park, Hole-in-wall Lake, 1960, E.W. Arnold 121. (CAN). The locality is more than 20° latitude further south than loacility of the type for the genus, and this specimens is considered to be merely a more robust specimen of Arctagrostis latifolia that was growing in warmer conditions. (Aiken and Lefkovitch 1990). • Holotype. Holotype specimen of Arctagrostis latifolia. Canada. Nunavut, Melville Island, 1819–1820, W.E. Parry. (Holotype: BM). Photograph by L. Consaul. • Distribution map. Arctagrostis latifolia map from Aiken and Lefkovitch, Can. J. Bot. 68: 2427. Dark circles = ssp. latifolia (open squares = subsp. arundinacea, see excluded taxa).
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).
