French marigolds, derived from Tagetes patula, include most of the dwarf cultivars, while the generally taller African cultivars arose from T. erecta. Hybridizing has also produced many cultivars with intermediate characteristics.
As a group, marigolds grow 8 to 42 inches tall, as low mounds or erect bushes. The 1-to 4-inch flowers may be rounded, tufted, or shaggy puffs in shades of white, yellow, orange, mahogany, maroon, and rust. Dark green leaves are dense, ferny, and often strongly scented.
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Other worthy marigolds include the signet group from T. tenuifolia, which has 8-inch mounds of lacy, lemon-scented leaves and ½-inch red, orange, or yellow single flowers. T. filifolia, Irish lace marigold, is grown for its dense 1-foot mounds of delicate foliage.