Stems 15-55 cm tall, somewhat angular above, simple or branched in upper part. Lvs 7.5-25 × 4-15 mm, ovate or oblong-ovate, glaucous; base of cauline lvs broad and cordate; apex acute. Cymes loose, few- to many-flowered. Pedicels slender, to c. 4 cm long, sometimes a few fls almost sessile. Calyx 8-12 mm long, lobed nearly to base; lobes acuminate. Corolla 10-15 mm long, bright yellow; lobes 6-9, lanceolate-oblong, patent, closing at night. Stamens as many as corolla lobes; anthers narrow-linear, = filaments. Stigmatic lobes erect at anthesis, later spreading. Capsule c. 1 cm long, ellipsoid. Seeds numerous, < 0.5 mm long, reticulate.