Survey of the vascular plants of Alert (Ellesmere Island, Canada), a polar desert at the northern tip of the Americas Author Desjardins, Émilie Author Lai, Sandra Author Payette, Serge Author Dubé, Martin Author Sokoloff, Paul C. Author St-Louis, Annie Author Poulin, Marie-Pier Author Legros, Jade Author Sirois, Luc Author Vézina, François Author Tam, Andrew Author Berteaux, Dominique text Check List 2021 2021-02-09 17 1 181 225 http://dx.doi.org/10.15560/17.1.181 journal article 10.15560/17.1.181 1809-127X Eriophorum scheuchzeri Hoppe subsp. arcticum Novoselova Figure 7B Materials examined. CANADA – Nunavut • Ellesmere Island, CFS Alert; 82°27′37″N , 062°51′53″W ; 16 m a.s.l.; 20 Jul. 2019 ; habitat: wetland on the margins of a lake, with peat and till as substrates, dominated by moss, Eriophorum scheuchzeri , and Eriophorum triste ; QFA 0635564. Identification. Plants 8–13 cm high; herbaceous; not caespitose. Fibrous roots and rhizomes present. Stems 6.5–11.0 cm long; erect; glabrous. Leaves basal and cauline; alternate. Sheath margins glabrous. Ligules 0.5– 3.1 mm long. Basal leaf blades 20–65 mm long, 0.5–2.0 mm wide; linear; folded; straight; abaxial and adaxial surfaces both glabrous; margins glabrous. Cauline bladeless leaves with sheaths brown apically and hyaline margins. Inflorescence a spike; 15–30 mm long. Bract absent. Spikelet spherical; bisexual, with both sexes in each floret; sessile. Proximal scales (4–6 empty scales proximally); 3.0– 6.3 mm long, 1–4 mm wide; ovate or lanceolate; grey or black, with hyaline margins; apices acute. Perianth represented by bristles; bright white. Androecium with 3 stamens and 0.5–1.5 mm long anthers. Gynoecium with 1 style and 3 stigmas. Fruit an achene; 1.5–2.2 mm long, 0.6–0.9 mm wide; obovoid or lanceoloid; glabrous. Four Eriophorum Linnaeus species are present on Ellesmere Island ( GBIF 2020). Only E. triste and E. angustifolium Honckeny subsp. angustifolium have more than two spikelets, whereas E. scheuchzeri and E. callitrix Chamisso have a solitary spikelet ( Saarela et al. 2020 ). E. scheuchzeri differs by having rhizomes and ≤7 empty proximal scales, whereas E. callitrix is caespitose (i.e., without rhizomes) and has usually ≥10 empty proximal scales ( Saarela et al. 2020 ). In addition, two subspecies of E. scheuchzeri are found on Ellesmere Island ( GBIF 2020) and can be differentiated according to the following characters: subsp. arcticum has spherical spikelets, whereas subsp. scheuchzeri has hemispherical spikelets; proximal fertile scales of subsp. arcticum are darker and gradually passing to paler grey tones with conspicuous hyaline margins, whereas proximal fertile scales of subsp. scheuchzeri are completely dark with dark margins or reduced, sharply differentiated hyaline margins ( Saarela et al. 2020 ).