Juncus biglumis Linnaeus

Desjardins, Émilie, Lai, Sandra, Payette, Serge, Dubé, Martin, Sokoloff, Paul C., St-Louis, Annie, Poulin, Marie-Pier, Legros, Jade, Sirois, Luc, Vézina, François, Tam, Andrew & Berteaux, Dominique, 2021, Survey of the vascular plants of Alert (Ellesmere Island, Canada), a polar desert at the northern tip of the Americas, Check List 17 (1), pp. 181-225 : 200

Juncus biglumis Linnaeus

Materials examined. CANADA – Nunavut • Ellesmere Island, CFS Alert ; 82°27′17″N, 062°35′55″W; 166 m a.s.l.; 11 Jul. 2019; habitat: mesic in a slope; QFA0635561 • same locality; 82°29′09″N, 062°00′03″W; 36 m a.s.l.; 30 Jul. 2019; habitat: mesic in a slope, with hummocks made of till and rocks, dominated by Stellaria longipes and moss; QFA0635562 .

Identification. Plants 2–8 cm high; herbaceous; caespitose or not caespitose. Fibrous roots and short rhizomes present. Stems 1.0– 7.5 cm long; erect; glabrous. Leaves basal. Sheaths hyaline or pale reddish-brown; margins glabrous. Basal leaf blades 16–40 mm long, 0.6–1.2 mm wide; linear; canaliculate or folded; green or purple; abaxial and adaxial surfaces both glabrous; margins glabrous; apices acuminate, sometime calloused, and black or dark purple. Inflorescence an anthela, with 1 or 2 flow- ers inserted on top of the other; 5.7–8.0 mm long. Bracts 5.0– 8.7 mm long; exceeding the inflorescence; spathi- form; green or reddish-purple; margins glabrous; apices acute and calloused. Bracteoles absent. Tepals 6; 2.1–3.9 mm long; 0.6–0.8 mm wide; lanceolate, oblong, or oblanceolate; purple; margins hyaline; apices obtuse. Androecium with 6 stamens and 0.5–0.8 mm long anthers. Gynoecium with 3 styles and 1 stigma per style. Fruit a capsule; 2.9–4.0 mm long, 1.3–1.9 mm wide; obvoid; trilocular; purple or reddish-brown, with dark purplish valve margins; glabrous.

Juncus biglumis can be separated from the three other Juncus Linnaeus species present on Ellesmere Island ( Aiken et al. 2007; GBIF 2020) by the following characters: flowers of J. biglumis are side by side in a vertical plane, in contrast to J. arcticus Willdenow , J. castaneus Smith subsp. leucochlamys (W.J. Zinger ex V.I. Kreczetowicz) Hultén , and J. triglumis Linnaeus subsp. albescens (Lange) Hultén , which have flowers ordered side by side in a horizontal plane; and anthers of J. biglumis (0.4–0.7 mm long) are smaller than the other species (≥ 0.7 mm long in J. arcticus , J. castaneus , and J. triglumis ; Aiken et al. 2007).