Annual or perennial herb or undershrub, with spreading or ascending branches, glabrous or pubescent; leaves alternate, subsessile, linear-lanceolate, mucronate, crenate to serrate, lower leaves broader than upper ones, stipules subulate, gland tipped; peduncles articulate; flowers solitary, axillary, purple, small, bisexual, irregular, bracteolate; pedicels shorter than leaves; sepals-5, subequal, not produced at the base, triangular, acuminate; petals 4, pink unequal, lowermost petal largest with an elongated, spurred claw towards base and a broad orbicular limb above; stamens-5, filaments, free or coherent, anthers free or connate, usually 2 (rarely 4) of them spurred or gibbous at the base; style clavate, incurved, stigma oblique, ovary ovoid, sessile, 1-celled, 3-parietal, placenta; capsules sub-globose, few seeded, 3 valved, seeds conspicuously ribbed.