Ranunculus sulphureus Solander, 1774

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 : 213-214

Ranunculus sulphureus Solander

Figure 14B

Materials examined. CANADA – Nunavut • Ellesmere Island, CFS Alert ; 82°25′52″N, 062°07′49″W; 296 m a.s.l.; 16 Jul. 2019; habitat: wetland in a mountain pass, with peat and rocks as substrates, dominated by moss

and Saxifraga cernua ; QFA 0634989.

Identification. Plants 4.0– 13.5 cm high; herbaceous; caespitose or not caespitose. Fibrous roots present. Stems 3.2–11.0 cm long; erect or ascending; glabrous proximally and hairy apically, with brown hairs. Leaves basal and cauline; heterophyllous; alternate; petiolate (basal leaves) or sessile (cauline leaves). Petioles 8–25 mm long; hairy. Basal leaf blades 5–15 mm long, 8–16 mm wide; widely depressed ovate or suborbicular; bases cuneate or truncate; lobed, with 3–5 main palmate, obtuse lobes; abaxial and adaxial surfaces both either glabrous or sparsely hairy, with brown hairs; margins ciliate. Cauline leaf blades 5–15 mm long, 6–18 mm wide; palmatisect, with 3–5 linear, obtuse lobes; abaxial and adaxial surfaces both either glabrous or sparsely hairy, with brown hairs; margins ciliate. Inflorescence a soli- tary flower. Sepals 5; 3–6 mm long, 3–4 mm wide; ovate or obovate; yellowish-brown; surface hairy, with brown hairs; margins ciliate; apices rounded. Petals 5; 4–9 mm long, 3–7 mm wide; obovate; unlobed; yellow. Androecium with 20–30, 1.2–2.0 mm long stamens. Receptacle 3.5–7.0 mm high; surface hairy, with brown hairs. Fruit an achene; 1.5–3.0 mm long, 1.0– 1.7 mm wide; ovoid; yellowish-green; with straight or curved beak; glabrous.

Ranunculus sulphureus and R. nivalis have brown hairs on sepals in contrast to pubescent with white hairs or glabrous sepals found in the six other Ranunculus species present on Ellesmere Island ( R. arcticus , R. aquatilis , R. hyperboreus , R. pygmaeus , R. sabinei , and R. subrigidus ; Aiken et al. 2007; GBIF 2020). The two species can be differentiated by the following: the basal leaf blades are shallowly lobed in R. sulphureus , whereas they are 3-parted in R. nivalis ; and the receptacles are hairy in R. sulphureus and glabrous in R. nivalis ( Saarela et al. 2020) .

Rosaceae – Rose family