A member of the Marigold family, Herb Mexican Tarragon grows to a small shrub in zones 8-11, and as an annual everywhere else. The plant is lovely, reaching about 2 feet tall and 12 to 15 inches wide. Tarragon Mexican blooms lightly in late spring, then heavily in early fall. Its super-bright, yellow blooms are half-inch wide and held in clusters atop bright green foliage.