Annual herb, 0.1-0.5(-1.0) m tall; stems procumbent or ascending, fleshy, pilose with fine, often glandular hairs. Leaves 2-6 (-11) cm long, 1.5-5(-6.5) cm broad, very variable, usually pinnatisect and ovate, occasionally almost entire and then lanceolate and incised, serrate, basally truncate or attenuate, lateral lobes in 1-2(-3) pairs, usually lingulate, acute or obtuse, the margin doubly serrate, occasionally laciniate, above green, pilose, beneath pale, glabrous or pilose on the midrib; petioles 1-6 cm long, often slightly winged distally, connate by a swollen ridge across node. Inflorescence varying from axillary pairs of pedicels to terminal, repeatedly dichotomous 5-30-flowered cymes; primary peduncles 1.5-9 cm long; pedicels 1-3 cm long, pilose or villose, often with gland-tipped hairs; bracts petiolate, entire, lanceolate, acute, the margin serrate; subordinate bracts frequently present. Flowers with the sepals 3-7 mm long, 1.5-3 mm broad, green, lance ovate, acute or acuminate, glabrous or puberulous, the margin denticulate; corolla small, sulphur yellow, glabrous, the upper lip 1-2 mm long, 2-3 mm wide, hooded, concealing the anthers, the lower lip 5-11 mm long, 3-6 mm wide, projecting, saccate most of its length, the proximal part appressed against the upper lip and closing the mouth; anthers 2.0-3.5 mm long, both cells fertile, much shorter than the elongated, linear connective; style 0.5-1.5 mm long, slightly curved. Capsule 3-9 mm long, broadly ovoid, glandular-pilose.