Very aromatic perennial herb, glabrous, erect from 30 to 95 cm; very resinous when dried. Opposite sessile, linear or oblong lanceolate leaves, 5 to 10 mm long, obtuse or sharp at the apex, finely dentate. Yellow flowers in small terminal heads, 9 to 10 mm in diameter, cylindrical involucre, commonly 3 bracts. Achenes of 6 to 7 mm, striate.

Tree of up to 10 m. Lanceolate or oblong-lanceolate leaves, 10 to 25 cm, acuminate. Pale-purple flowers, few in number and in terminal corymbs; 1 cm turbinate calyx tube, long, rounded lobes; glandular petals from 1 to 1.5 cm. Round or oval fruit 3 to 6 cm long, pale yellow.