1. Tagetes erecta L. (common marigold, African marigold)

Pl. 290 e, f; Map 1233

Stems 10–50(–120) cm long. Heads mostly 6–10 cm in diameter (including the spreading ray corollas), the stalk relatively strongly inflated or swollen toward the tip, often hollow. Involucre 17–22 mm long. Ray florets with the corolla 15–25 mm long, yellow or orange. Disc florets with the corolla 10–16 mm long. Pappus scales variously 5–12 mm long. Fruits 7–11 mm long. 2n=24. July–October.

Introduced, uncommon and sporadic (native of Mexico, widely introduced in tropical and temperate regions nearly worldwide). Railroads and open, disturbed areas.

The common marigold is cultivated widely as a bedding plant and as a cut flower. It has a number of ceremonial and religious uses in Mexico and has also been used medicinally for a number of ailments and as an insect and tick repellant. A yellow dye can be extracted from the flowers. Tagetes erecta is one of four closely related taxa that have been bred and selected intensively in cultivation. Because it is so widely cultivated in Latin America, its native range is poorly understood. This taxon is a diploid (2n=24) that may have been crossed with another diploid cultivated species, T. tenuifolia Cav., long ago to produce the fertile tetraploid (2n=48) taxon T. patula (Neher, 1966).