Plants annual, 40-60 cm tall, glabrous. Stem erect, usually purple-tinged, branched. Leaves alternate, petiolate; leaf blade broadly elliptic to ovate, 7-13 × 3-6 cm, with 1 or 2 pairs of stipitate basal glands, both surfaces nearly glabrous, setose between teeth, lateral veins 7 or 8 pairs, base cuneate, narrowed, margin crenate, apex acute. Inflorescences in upper leaf axils of stem and branches, racemose, 5-12-flowered; peduncles erect or ascending, 6-12 cm. Pedicels 1.5-2 cm, slender, glabrous, bracteate at base; bracts caducous, navicular-ovate, 0.8-1 cm, apex aristate. Flowers yellowish, small, 1.5-2 cm deep. Lateral sepals 2, falcate-elliptic, ca. 2 mm, apex aristate. Lower sepal navicular, narrowed into an erect or curved spur; spur ca. 3 cm, slender. Upper petal yellowish, slightly cucullate, obovate, ca. 8 × 6 mm, abaxial midvein carinate; lateral united petals not clawed, yellowish, reddish spotted, ca. 1.8 cm, 2-lobed; basal lobes obtriangular, ca. 9 × 3 mm, apex rounded; distal lobes narrowly curved-lanceolate, ca. 14 × 5 mm, apex slightly rounded; auricle absent or very narrow. Filaments linear; anthers obtuse. Ovary fusiform, glabrous. Capsule not seen. Fl. May. 2n = 18*.
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