Trisetum spicatum (L.) K. Richter
Pl. Eur. 1: 59. 1890
Aira spicata L. Sp. Pl. 64. 1753. Trisetum alaskanum Nash, Bull. New York Bot. Gard. 2: 155. 1901. Trisetum spicatum var. alaskanum Malte ex Louis-Marie, Rhodora 30: 239. 1928. Trisetum spicatum subsp. alaskanum Hultén, Svensk Bot. Tidskr. 53: 210. 1959.
Type: Described from Northern Sweden, Lapland (Tzvelev 1976).
Avena mollis Michx., Fl. Bor. Amer. 1: 72. 1803. Trisetum spicatum var. molle (Michx.) Beal, Grasses N. Amer. 2: 377. 1896. Trisetum spicatum var. pilosiglume Fern. Rhodora 18: 195. 1916. Type: Canada. Newfoundland: Notre Dame Bay, 1911, M.L. Fernald, K.M. Wiegand and E.B. Bartram 4593. (Isotype: CAN!)
Plants caespitose; less than 15 cm high, or more than 15 cm high; 10–40 cm high. Ground-level or under-ground stems not developed horizontally or vertically at, on, or below, the ground. Aerial stems erect; densely hairy. Leaves mostly in a basal tuft. Sheaths with the margins fused only in the lower part; with trichomes; hirsute. Ligules 0.8–3 mm long; a fringed membrane; hairy; transversely oblong; apices acute to truncate; erose, or lacerate. Blades 17–85 mm long; 1.2–2.2 mm wide (when flat); appressed to the stem, or spreading; rolled in bud (very prominent ribs may lead to margins touching, as with blades folded in bud); flat, or involute; midvein similar in size to other veins in the leaf. Blades adaxial surface hairy. Blades abaxial surface hairy (softly villous, or puberulent).
Flowering culm nodes not exposed. Inflorescence paniculate (dense, cylindrical or ovoid, often deep purple brown, with prominent twisted, geniculate awns); dense; linear; 2–5 cm long; 5–13 mm wide. Inflorescence. Inflorescence main axis hairy (strongly pubescent with long, soft hairs). Number of inflorescence branches at lowest node 3–4. Inflorescence primary branches 0.2–0.8 mm long; scabrous (hairy); with appressed secondary branches, or with spreading secondary branches. Spikelets. Spikelets pedicellate (pedicels are very short); disarticulating above the glumes; laterally compressed; lanceolate, or ovate; 3.9–6.6(–7.5) mm long; 1.5–3 mm wide. Florets per spikelet 2–3. Glumes. First glume 0.74–0.85 × the length of the second glume; 0.6–0.7 × spikelet length; 2.5–4.5 mm long; lanceolate; glabrous; margins ciliate (very few and short hairs); veins 1; apex acuminate. Second glume 0.4–0.9 × as long as the spikelet; almost as long as, or longer than, the lowest floret; lanceolate; 3.4–5.5 mm long; glabrous, or with trichomes (scaberulous on keel); veins 3. Rachilla internode 0.8–1.2 mm long; hairy. Rachilla not pronounced between the florets; extending beyond the uppermost floret. Callus differentiated; hairs 0.1–0.3 mm long; hairs shorter than the floret. Lemmas. Lemma (3.5–)4.5–5.3 mm long; lanceolate; keeled (slightly); surface dull; surface sparsely scabrous; veins 3. Lemma apex acute; entire; glabrous; awned. Awn arising from below the apex but above the middle (affixed at the upper third or fourth of the lemma, bent and twisted). Palea well developed; 3.7–4.2 mm long; with scabrous veins. Perianth reduced to lodicules. Anthers (0.6–)1–1.2 mm long. Styles 2. Fruit sessile. Fruit dry; indehiscent. Fruit 2.3–2.7 mm long. Seeds 1.
Chromosome information. 2n = 28 (Löve and Löve 1975, 35 records).
Distribution. Circumpolar. Arctic, or alpine. Range in the Canadian Arctic Archipelago widespread. Arctic Islands: Baffin, Devon, Ellesmere, Axel Heiberg, Parry Islands, Banks, Victoria, Prince of Wales, Somerset, Southampton, Coats.
Ecology and habitat. Substrates: river terraces, lake shores, tundra, slopes, ridges, cliffs, seashore (but above tidal influence); on seepage slopes, on solifluction slopes, dry, moderately well drained; acidic, or calcareous, or nitrophilous; rocks (granite, gneiss, or sandstone scree), gravel, sand, silt, clay, till. Habitats: Commonly found in well-drained, silty, sandy, or gravely soils, often at the edge of disturbed terrain, such as the edge of solifluction lobes, thaw-flow slides, and around disturbed construction sites in settlements.
Taxon as an environmental indicator. This species is an early coloniser of disturbed sandy and silty ground. The plants are relatively short and are eventually crowded out of a habitat by taller grass species such as Poa glauca.
Notes. Hultén (1959) reported on the T. spicatum complex and recognised several varieties, stating that plants in the High Arctic conform closely to subsp. spicatum in having dense spike-like inflorescences and a violet colour zone on the glumes and lemmas, while their margins are brown. The culm is strongly pubescent with long, soft, and (except at the top) downward pointing hairs. The panicle branches are pubescent as well as the sheaths and the awn is affixed at the upper third or forth of the lemma and bent and twisted. The flowers considerably overtop the glumes. Randall and Hilu (1986) studied T. spicatum throughout its North American distribution and concluded that the data for 33 morphological characters revealed extreme variation within the species and did not support the recognition of infraspecific taxa or the elevation of the hexaploids to specific rank.
Illustrations. • Laboratory photograph. Nunavut, Baffin Island, Iqaluit, Aiken, 94–023. (CAN). Photograph taken August 1994, by K. Clarkin. • Close-up of inflorescence. Nunavut, Baffin Island, Iqaluit, Aiken 94–023. (CAN). Laboratory photograph showing close-up of inflorescence with curved awns extending beyond the compact spikelets. Photograph taken August 1994, by K. Clarkin. • Isotype, var. pilosiglume. Trisetum spicatum var. pilosiglume. Canada. Newfoundland, Notre Dame Bay, 1911, M.L. Fernald, K.M. Wiegand and E.B. Bartram 4593. (Isotype: CAN). • Distribution map.
Cite this publication as: ‘S.G. Aiken, L.L. Consaul, and M.J. Dallwitz. 1995 onwards. Poaceae of the Canadian Arctic Archipelago: Descriptions, Illustrations, Identification, and Information Retrieval. Version: 10th December 2001. http://www.mun.ca/biology/delta/arcticf/’. Dallwitz (1980), Dallwitz, Paine and Zurcher (1993, 1995, 2000) , and Aiken, Dallwitz et al. (1999) should also be cited (see References).
