Family - Asteraceae

Stems - To +2m tall, winged,(wing to +/-3mm broad), erect, herbaceous, pubescent, from fibrous roots, typically simple, single or multiple from base.

Winged stem.

Leaves - Alternate, petiolate. Petioles winged(tissue decurrent on stem). Blade ovate to oblong-lanceolate, to +15cm long, +6cm broad, acute to acuminate, typically glabrous above, sometimes scabrous, appressed hairy to short hirsute below, typically entire.

Inflorescence - Terminal corymbiform cluster of many flower heads. Peduncles pubescent to subtomentose.

Involucre - To -1cm tall (long), 5-6mm broad. Phyllaries imbricate, linear-oblong, densely pubescent, appressed, acute.

Involucre.

Ray flowers - Fertile (pistillate), ~5 per flower head. Ligule white, glabrous, to 9mm long, 5mm broad, notched at apex, broadly oblong.

Disk flowers - Disk to +5mm broad. Flowers +/-7 per head. Corolla whitish, 5 lobed. Lobes acute, +1mm long, spreading. Stamens 5, slightly exserted. Anthers purplish-black, to 2mm ong, connate around style. Style whitish, bifurcate, exserted. Achenes compressed, typically winged. Pappus of two short awns.

Flowering - August - October.

Habitat - Open woods, streambanks, thickets.

Origin - Native to U.S.

Other info. - This plant is common in the southern half of Missouri and apparently absent in the northern half of the state. There are yellow flowered species of this genus in Missouri but this is the only white flowered species. The winged stems and dense corymbiform clusters of flower heads are good characteristics for identifying the plant in the field.

Photographs taken in the Ozark Scenic Riverways, Shannon County, MO., 8-20-03.