Plants annual, 10-20 cm tall, glabrous. Stem erect, basally pink, slender, simple, with few fibrous roots. Leaves opposite in lower part of stem, alternate in upper part of stem; petiole 0.5-1 cm; leaf blade ovate-lanceolate, 1-4 × 0.7-2 cm, membranous, without glands, lateral veins 3-5 pairs, base cuneate, margin crenate serrate, apex acuminate. Inflorescences solitary, in upper leaf axils, ca. 1.5 cm, 1-flowered. Pedicels bracteate above middle; bracts persistent, elliptic, 2-3.5 mm. Flowers pink, ca. 2.5 cm deep. Lateral sepals 2, ovate, ca. 3.5 × 2.5 mm, 3-veined, margin entire, apex conspicuously mucronulate. Lower sepal narrowly funnelform, ca. 1.8 cm deep, gradually narrowed into an incurved spur ca. 1.2 cm; mouth vertical, 5-6 mm wide, tip mucronulate. Upper petal suborbicular, ca. 4.5 × 5 mm, apex obtuse, abaxial midvein narrowly carinate; lateral united petals ca. 8 mm, 2-lobed; basal lobes ovate-oblong; distal lobes dolabriform, apex rounded. Filaments linear, ca. 2 mm; anthers ovoid, apex obtuse. Ovary fusiform, ca. 2 mm. Capsule (immature) fusiform. Fl. Apr.
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