Herb 40-70 cm high, forming large colonies, stems thick and covered with withered leaves. Leaves alternate, sessile, densely imbricate, linear-lanceolate, 20-35 x 3-5 cm, dark green above, purple beneath and along the margins; inflorescence axillary,  umbelliform cyme enclosed by compressed spathe-like bracts, 3-4.5 cm broad and 2-3 high, petals white 5-8 mm long; capsule 3-angled 4.5 mm long.

Densely branching, aromatic, shrub, 20-30 cm high.  Leaves lanceolate, entire, 0.5-1 cm x 0.2-0.5 cm, grayish-green, aromatic with glandular-dotted; flowers born in rounded or ovoid cluster, corolla 2-lipped, lilac, pink or purple; fruits tiny producing 4 nutlets.

Shrub or small tree 3-7 m high, glabrous with milky sap. Leaves spirally arranged, linear, 10-15 x 0.6-1cm, shiny on the upper side; Inflorescence terminal cymes, few-flowered; corolla tubular-campanulate, flower 7-8.5 cm long, bright yellow or pinkish-orange; fruit sickle-shape, 2 x 3 cm, yellow when ripe with a single triangular seed 2 x3 cm.

Perennial and suffruticose herb, aromatic, up to 1 m high.  Leaves ovate to oblong-ovate, ca. 12 cm long, lower ones pinnate and pinnatisect, upper ones broadly pinnati-divided; segments 2 to 3 pairs, dentate, obtuse.  Small heads numerous, up to 2 cm in diameter; disc yellow; flowers radiate, white.

Annualherb, highly scented, glabrous, erect, 30-95 cm; very resinous when dried.  Leaves opposite, sessile, linear or oblong-lanceolate, 5-10 mm long, obtuse or acute at the apex, finely dentate.  Flowers yellow, in small terminal heads, 9-10 mm in diameter, involucre cylindrical, bracts usually 3 in number.  Achenes 6-7 mm long, striate.