Fleischmannia incarnata (Walter) R.M. King & H. Rob.
Family - Asteraceae
Stem - Loosely ascending, to 1.2 m, branched, pubescent with short, curly hairs.
Leaves - Opposite at widely spaced nodes, sessile or petiolate, roughly triangular, usually cordate at base, margins scalloped, densely pubescent abaxially.
Inflorescence - Flat-topped panicles of heads at branch tips.
Involucres - Cylindrical or narrowly bell-shaped, 3-5 mm long, with 18-30 bracts in 2-3 subequal overlapping series.
Flowers - Disk florets 13-25 per head. Corollas pale pink or lavender to nearly white. Pappus of numerous capillary bristles. Rays absent.
Fruits - Achenes 1.8-2.5 mm, finely ribbed, tapered, glabrous, brown or black.
Flowering - August - October.
Habitat - Swamps, bottomland forests, streamsides, ditches.
Origin - Native to North America.
Other info. - This is an uncommon species in Missouri. In appearance it is reminiscent of a tall, gangly ageratum with pale pinkish florets and catnip-like leaves. The plant is indeed most closely related to ageratums such as Conoclinium coelestinum. It is found in the far southern regions of the state, primarily in the Mississippi Lowlands division.
Photographs taken at Holly Ridge Conservation Area, Stoddard County, MO, 10-5-2011, and at General Watkins Conservation Area, Scott County, MO, 10-4-2017 (SRTurner).