About Helianthus angustifolius L.
Helianthus angustifolius is a species of sunflower that has the common names narrowleaf sunflower and swamp sunflower. It is native to the south-central and eastern United States, occurring in every coastal state from Texas to Long Island, and extending inland as far as Missouri. It is most commonly found in Atlantic and Gulf coastal plain habitats, especially in wet areas. While this species generally prefers low, moist ground, it can tolerate a range of conditions from bogs and swamps near sea level to relatively dry, well-drained gravelly clay. It is not especially resistant to drought. Helianthus angustifolius is frequently cultivated for its bright, showy yellow flowers. It is a perennial herb that can grow up to 150 centimetres (59 in) tall. Its leaves are long and narrow, reaching up to 15 centimetres (5.9 in) in length. A single plant can produce 3 to 16 flower heads; each flower head holds 10 to 20 ray florets surrounding at least 75 disc florets.
