Pleuropogon sabinei R. Br.
Semaphore grass.
Poaceae, grass family.
Chlor. Melvill. 31. 1823.
Type: Canada. Melville Island, Sabine et al. W. E. Parry's voyage, 1819–1820. (Isotype: GH!).
Pleuropogon sabinii f. aquaticus Simmons, Rep. 2nd Norwegian Arct. Exp. Fram, 2: 170. 1906. Type: Canada. Nunavut: Ellesmere Island, Fram Fjord, ("in lacubus, rivulis, etc." 26 Aug. 1899, H.G. Simmons 1600. (Holotype: O! Isotype: CAN!).
P. sabinii f. terrestris Simmons. Rep. 2nd Norwegeian Arct. Exp. Fram 2: 170. 1906. Type: Canada. Nunavut: "Ellesmerelandiae, In sinu Fram Fjord," 26 Aug. 1899. H.G. Simmons 1666. (Isotype GH!).
Plants less than 15 cm high, or more than 15 cm high; 4–30 cm high (emergent). Ground-level or under-ground stems horizontal; rhizomatous; elongate, or compact; 1–2 mm wide. Scales present; smooth; 10–40 mm long; glabrous. Aerial stems erect, or decumbent; circular or oval in cross-section; glabrous. Leaves distributed along the stems (submerged leaves lax and floating, emergent leaves erect); alternate; marcescent. Petioles absent. Sheaths with the margins fused to the apex; glabrous; collars collars present. Ligules present; 0.9–2.7(–3.5) mm long; membranous, or a fringed membrane (on the isotype); glabrous, or hairy; ovate-oblong; apices obtuse; entire. Blades 20–230 mm long; 1.5–3 mm wide (when flat); appressed to the stem, or spreading from the vertical; folded in bud; linear; flat, or folded; with parallel veins; midvein conspicuously larger than the lateral veins (sometimes with an associated thickened ridge of tissue below the abaxial surface); bulliform cells in distinct rows on either side of the midvein; adaxial surface glabrous. Blades abaxial surface glabrous.
Flowering culm nodes rooting at the lower nodes; not exposed (when culms emerge), or becoming exposed (when culms remain submerged); number visible 0–3. Inflorescences racemose (with long spikes arranged as though signalling semaphore); inflorescence diffuse; inflorescence linear; inflorescence 3–6.5(–8) cm long; inflorescence 2–7 mm wide; inflorescence main axis glabrous. Number of inflorescence branches at lowest node 1. Spikelets pedicellate; disarticulating above the glumes; laterally compressed; oblong; 8–18 mm long; 1.7–5 mm wide. Florets per spikelet 6–10. First glume 0.4–0.9 × the length of the second glume; 0.1–0.2 × spikelet length; 1.3–1.6 mm long; lanceolate, or ovate; glabrous; margins glabrous; veins 1 (faint); apex obtuse. Second glume 0.4 × as long as the spikelet or less; shorter than the lowest floret; 1.5–3(–4.3) mm long; ovate; glabrous; veins 3. Rachilla internode 0.8–1.3 mm long; glabrous. Rachilla not pronounced between the florets; extending beyond the uppermost floret. Lemma 3.5–4.7 mm long; oblanceolate; rounded on the back; surface dull; surface sparsely scabrous; surface with trichomes on and between the veins; veins (6–)7. Lemma apex rounded, or truncate; entire, or erose, or lacerate; not ciliate; awnless. Palea well developed; 3.4–4.5 mm long; with scabrous veins (a dark purple, scabrous, awn 1.5–2 mm long arises near the base of each palea keel and often protrudes from the edges of the spikelet). Perianth reduced to lodicules. Stamens 3. Anthers 1.6–2.6 mm long. Carpels syncarpous; 3. Gynoecia superior. Styles 2. Ovules 1. Fruit a caryopsis; indehiscent; 2–2.2 mm long; sessile; dry. Seeds 1.
Chromosome information. 2n = 42 (Bowden 1960a).
Distribution. Amphi-Atlantic. High arctic. Range in the Canadian Arctic Archipelago widespread. Arctic Islands: Baffin, Devon, Ellesmere, Axel Heiberg, Parry Islands, Conrwallis, Banks, Victoria, Prince of Wales, Somerset, King William, Southampton, Coats (Ellef Ringnes).
Ecology and habitat. Substrates, wet meadows, around the margins of ponds (emergent or at the edges), marshes, along streams, lake shores, tundra; aquatic, imperfectly drained moist areas; acidic (granite, gneiss, CAN 514341), or calcareous; silt, moss. Plants grow in the shallow waters of ponds, lakes, or sluggish streams, or on poorly drained soils around ephemeral ponds and terrain that is flooded earlier in the summer. On soft muddy shores of small sheltered ponds plants of this species may form pure stands. Pleuropogon sabinei has been found in the small pond used as a water reservoir by Parks Canada at Tanquary Fiord, Ellesmere Island, 81°N, 79°45'W, and is common in the ponds to the west of the Polar Continental Shelf Base, at Resolute, Cornwallis Island 71°41'N, 94°54'W.
Taxon as an environmental indicator. Indicative of low lying areas where water accumulates for much of the growing season and the substrate remains damp all season.
Notes. This species has the most northern distribution for an emergent grass. Data for Canadian samples suggests some specimens are larger plants than those that occur in Europe. The taxon was named for the Arctic explorer Edward Sabine. The spelling of "sabinii" appears to have been a deliberate latinizing of the name by Robert Brown and according to the International Code of Botanical Nomenclature, Articles 60,1 and 60,3 the spelling should be corrected (Greuter et al. 1994).
Illustrations. • Plant habitat. Plants growing in shallow pond on calcareous silt. Note aquatic leaves that tend to float on the surface of the water. Nunavut, Cornwallis Island, Resolute Bay. S.G. Aiken 98–057. Photograph by Mollie MacCormac. • Plant habitat. Plants growing in shallow pond on calcareous silt. Note "semaphore" positions of the spikelets on the aerial culms and the floating aquatic leaves. Nunavut, Cornwallis Island, Resolute Bay. S.G. Aiken 98–057. Photograph by Mollie MacCormac. • Close-up of plant. Aerial culms with developing inflorescences that have few many flowered spikelets. Plants growing in shallow pond on calcareous silt. Nunavut, Cornwallis Island, Resolute Bay. S.G. Aiken 98–057. Photograph by Mollie MacCormac. • Laboratory photograph. Nunavut, Cornwallis Island, Resolute Bay, plant brought in from wet area west of Polar Continental Shelf Project station. S.G. Aiken 93–079. (CAN). Photograph G. Steel, August 1993. • Possible isotype specimen. Canada, Melville Island, 1819–20, Sabine, Edwards, Ross et al. (Possible Isotype: GH). • Isotype, forma terrestris. Pleuropogon sabinei f. terrestris Nunavut, Ellesmere Island, Fram Fjord, 1899, Herman G. Simmons 1666. (Isotype: GH). This name has not been widely taken up. • Isotype, forma aquaticus. Pleuropogon sabinei f. aquaticus. Nunavut, Ellesmere Island, Fram Fjord, 1899, Herman G. Simmons 1600. (Isotype: CAN). Recognition of the forma as distinct has not been widely taken up. • Distribution map.
Cite this publication as: ‘S.G. Aiken, M.J. Dallwitz, L.L.Consaul, R.L. Boles, R. Elven and M.E. LeBlanc. 2001 onwards. Flora of the Canadian Arctic Archipelago. Volume 1. Pteridophytes and Monocotyledons: Descriptions, Illustrations, Identification, and Information Retrieval. Version: 16th March 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).
