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 Draba corymbosa R. Brown ex de Candolle Figure 5D, E Materials examined. CANADA – Nunavut • Ellesmere Island, CFS Alert; 82°26′22″N , 062°50′39″W ; 201 m a.s.l.; 7 Aug. 2019 ; habitat: barren ground in a slope, with till and rocks as substrates; QFA 0635552, CAN • same locality; 82°31′03″N , 062°26′21″W ; 57 m a.s.l.; 26 Jun. 2019 ; habitat: barren ground, with polygonal patterned ground made of till and rocks, and sparse dominance of Saxifraga oppositifolia and Poa abbreviata R. Brown ; QFA 0635553, CAN • same locality; 82°31′35″N , 062°18′19″W ; 5 m a.s.l.; 3 Aug. 2019 ; habitat: wetland, with peat as substrate, dominated by Salix arctica , Saxifraga oppositifolia , and moss; QFA 0635584. Identification. Plants 2–4 cm high; herbaceous; caespitose. Taproots and rhizomes present. Stems 1.0– 3.5 cm long; erect or ascending; hairy, with simple and branched hairs (2–5 rays: T , V , Y , cruciform, ternate, and dendritic). Leaves basal; alternate or whorled; petiolate or subsessile. Petioles 2–5 mm long; winged; margins ciliate, with simple hairs. Leaf blades 3–12 mm long, 1.4–3.8 mm wide; obtrullate or oblanceolate; bases attenuate; abaxial and adaxial surfaces both moderately to densely hairy, with simple and branched hairs (2–5 rays: Y , V , ternate, and dendritic); margins ciliate, with simple hairs; apices obtuse. Inflorescence a corymbose raceme, with 2–4 flowers; not elongating as the fruit matures or slightly elongating as the fruit matures. Pedicels 1.5–6.0 mm long; hairy. Sepals 4; 2.4–3.5 mm long, 1.1–2.1 mm wide; ovate; green or yellow, with yellow margins; surface hairy, with simple and few branched hairs (2 rays: Y and V ); margins glabrous; apices obtuse or acute. Petals 4; 3.8–5.3 mm long; 2.0– 2.9 mm wide; obovate; slightly lobed or undulating; yellow. Androecium with 6 stamens and 0.4–0.6 mm long anthers. Gynoecium with 1 style and 1 stigma. Fruit a silique; 4–11 mm long, 2.3–4.4 mm wide; ovate or lanceolate; flattened; green or purple; hairy, with simple and branched hairs (2 rays: Y , V , and T ). Styles persisting in fruits 0.4–0.7 mm long, 0.2–0.4 mm wide. Stigmas 0.5–0.9 mm wide; distinctly larger than the styles. Among the yellow-flowered Draba species present on Ellesmere Island ( D. alpina Linnaeus, D. arcto- gena ( E . Ekman) E . Ekman, D. micropetala Hooker , D. oblongata R. Brown ex de Candolle , and D. pauciflora ; Aiken et al. 2007 ; GBIF 2020), D. corymbosa and D. simmonsii Elven & Al-Shebaz are characterized by larger petals ( 2–4 mm wide; Aiken et al. 2007 ; Elven and Al- Shehbaz 2008; Garneau and Sabourin 2018). D. corym- bosa also has wider fruits ( 3.1–5.5 mm wide) and longer styles persisting in fruits (0.4–1.0 mm long) compared to D. alpina , D. micropetala , and D. simmonsii , which have 1.9–3.8 mm wide fruits and 0.05–0.30 mm long styles (Elven and Al-Shehbaz 2008; Al-Shehbaz et al. 2010b ; Garneau and Sabourin 2018). D. corymbosa has mainly branched hairs on the abaxial leaf surface, whereas the other yellow-flowered Draba species have simple or simple and branched hairs (Al-Shehbaz and Mulligan 2013; Saarela et al. 2020 ).