- To 3m tall, from fibrous and fleshy roots, erect, branching, single or multiple from the base, slightly fragrant, glabrous, glaucous, herbaceous.
- Alternate, petiolate, reduced to bracts in inflorescence and often unlobed near the apex of the plant. Petioles to +10cm long, with a shallow adaxial groove. Blades deeply lobed (the lobes often divided again), to +/-25cm broad, +/-40cm long. Lobes serrate, deep green above, light green below, glabrous but the margins of the serrations often antrorse strigillose. The lateral venation splitting at the base of the sinuses.
- Loose cymose arrangement of terminal flowerheads, bracteate. Peduncles to 15cm long.
- Flat, to -3cm broad. Phyllaries unequal, some or all reflexed, linear oblong, in one or two series, to 1.5cm long, -6mm broad, acute, green, glabrous.
- +/-9 per flowerhead, sterile. Ligule yellow, antrorse appressed pubescent externally, glabrous internally, with a single notch at apex, oblong-elliptic, 1.3cm broad, +/-4cm long. Achenes 3mm long in flower, glabrous, angled.
- Disk to 2cm in diameter, conic to globose. Corolla yellow, glabrous, 5-lobed, -4mm long. Lobes erect, .6mm long, triangular. Stamens 5, adnate at the base of the corolla tube. Filaments yellow, compressed, glabrous, 2mm long. Anthers deep purple, connate around the style, -2mm long, mostly exserted. Style exserted, bifurcate, the apices spreading, glabrous, pale yellow. Achenes in flower pinkish, 4-angled, 4mm long, glabrous, becoming deep purple to black and 5mm long in fruit. Receptacle cylindric. Chaff slightly enclosing the achenes, pubescent at the apex, whitish to whitish-green, 5mm long.
Disk flowers close-up.
- July - September.
- Rich low woods, streambanks, woodlands along lakes and sloughs, wet thickets.
- Native to U.S.
- This species is common throughout Missouri. The plant gets quite large and produces many flowers. Some varieties of this species are cultivated frequently.
Traditionally the plant was used to treat indigestion, burns, and other ailments. The plant may be toxic if eaten in large quantities.
The species epithet "
" means "torn" because of the divided nature of the leaves.
Photographs taken in the Ozark National Scenic Riverways, Shannon County, MO., 8-2-03.