Family - Asteraceae

Stems - To +2.5m tall, purple, glabrous, single from the base, branching in inflorescence, from a taproot, with pure-white milky sap, erect, herbaceous.

Leaves - Alternate, sessile. Basal leaves toothed(dentate), pinnately lobed, to +15cm long, +9cm broad, terminal lobe triangular. Cauline leaves toothed, lobed to unlobed, glabrous, with triangular, sagittate terminal lobe.

Inflorescence - Paniculate arrangement of flower heads at the apex of the main stem.

Involucre - Vase shaped to cylindric. Phyllaries imbricate, green with purple apices.

Involucre.

Ray flowers - 10-16 flowers per head. Corolla light blue, sometimes whitish. Ligules to 6mm long, apex toothed. Flower head +/-12mm broad, when fully opened. Achenes brown, to 5mm long, ribbed, typically with short beak. Pappus to +/-8mm long, of white capillary bristles in more than one series.

Flower close-up.

Fruits close-up.

Disc flowers - Absent.

Flowering - August - October.

Habitat - Open woods, thickets, disturbed sites, waste ground, streambanks, roadsides, railroads.

Origin - Native to U.S.

Other info. - Although the inflorescence can have over 100 flower heads at once, these open just a few at a time. The plant will secrete a pure-white milky juice if bruised. There are a few variations which are mostly differentiated on leaf shape and/or flower color. I won't go into those here.
Prior to flowering, this species greatly resembles another in the genus, L. canadensis L., but L. canadensis has sap with a salmon color to it.
The genus name may remind you of "lettuce" and indeed this genus is wild lettuce and is quite edible although slightly bitter. The next time you slice a head of store-bought lettuce, watch for the milky juice that comes from the leaves.

Photographs taken at the Kansas City Zoo, 10-25-99, and in Brown Summit, NC., 9-21-02.