13. Physaria calderi (G. A. Mulligan & A. E. Porsild) O’Kane & Al-Shehbaz, Novon. 12: 322. 2002.
Lesquerella calderi G. A. Mulligan & A. E. Porsild, Canad. J. Bot. 47: 215, plate 1. 1969; L. arctica (Wormskjold ex Hornemann) S. Watson subsp. calderi (G. A. Mulligan & A. E. Porsild) Hultén
Perennials; caudex simple or branched; densely pubescent throughout, trichomes (sessile or subsessile), rays distinct or slightly fused at base, furcate or bifurcate, (strongly umbonate, tuberculate, tubercles often relatively larger, fewer over center). Stems simple or few to several from base, usually erect to spreading, sometimes prostrate, 0.5-2 dm. Basal leaves: blade oblanceolate, 2-3 cm, margins entire. Cauline leaves (sessile or proximal shortly petiolate); blade narrowly oblanceolate, 0.5-1.5 cm, margins entire. Racemes loose. Fruiting pedicels (erect to divaricate or ascending, sometimes curved), (5-)10-20(-40) mm, (stout). Flowers: sepals ovate to elliptic, (3-)4-5(-6) mm, (median pair often thickened apically, cucullate); petals obovate, (6-)7-10 mm (nearly as wide, abruptly narrowed to claw, ca. 1 mm wide). Fruits subglobose to ellipsoid, compressed (usually angustiseptate), to 8 mm; (valves not retaining seeds after dehiscence; replum as wide as or wider than fruit; ovules 10-14 per ovary; style 1-2 mm. Seeds plump. 2n = 20.
Flowering Jun-Aug. Dry rocky summits, limestone flats and slopes, alpine knolls; 600-1500 m; N.W.T., Yukon; Alaska.
Physaria calderi is known from the Ogilvie and Richardson mountains.