Annual or perennial herb, upright, up to 1.5 m, very aromatic. Lanceolate to elliptic, sinuate-dentate, acute, up to 13 cm, glandular leaves. Flowers in dense clusters or in spikes; 3 to 5 sepals, ovate; petals absent. Small fruit inside the calyx with black seeds.

Woody climbing plant. Leaves ovate to lanceolate, acuminate or acute, from 6 to 18 cm. Axillary or terminal inflorescences of up to 20 cm; flowers 3 to 4 mm; white or greenish sepals, oval to oblong. 4 to 5 mm long globular to ovoid utricle; black lenticular or reniform seeds.

Herbaceous annual, stems 30 cm high, tomentose and with abundant yellowish hairs. Opposite leaves with short petioles, ovate to lanceolate laminae, almost always rhombiform, 1 to 3 cm long, rounded base, acute apex, serrated margins, almost always with red or purple spots. Terminal and axillary inflorescences, pedunculate, with small purple glands. Capsules from 1 to 1.2 mm long, pubescent-strigose.

Herbaceous or subshrub of up to 80 cm, with milky white latex. Opposite obovate, elliptic or oblong leaves, 3 to 7 cm long. Sessile flowers, white or pink, with 5 petals joined by the base forming a tube with free lobes, solitary or in groups in the axils of the leaves. Trilobular fruit, pubescent, containing 2 to 3 black seeds, about 0.5 cm in diameter.

Tree up to 25 m tall. Simple elliptic-lanceolate leaves, up to 12 cm, acuminate. White flowers, with red lines, yellow inside, petals of 1 cm. Very narrow and long capsule, up to 60 cm, sometimes more and 3 mm wide; feathery-pubescent seeds.