Symphyotrichum praealtum (Poir.) G.L. Nesom
Family - Asteraceae
Stem - Stems to 150 cm, usually branched above the midpoint, sparsely to moderately pubescent toward the tip with hairs usually in longitudinal lines or bands, usually glabrous toward the base, often somewhat glaucous.
Stem and leaves.
Leaf - Basal and lower stem leaves usually absent at flowering. Stem leaves simple, oblong, lanceolate, or elliptic, tapered at base, entire or sparsely toothed, sessile but not clasping. Venation on abaxial surface conspicuous.
Inflorescence - Panicles with spreading or ascending branches.
Heads - 1.5-2.5 cm in diameter.
Involucres - 4-7 mm long, cup shaped. Bracts in 4-5 unequal, overlapping series, ascending, linear-lanceolate, sharply pointed at tip, lacking a bristle-like extension, pale with a darker green tip, glabrous or sparsely hairy toward tip.
Florets - Ray florets 20-35 in 1 or 2 series, pistillate, with lavender to purple ligules 5-12 mm long. Disk florets 20-35, yellow becoming red-brown after pollination, expanded portion of corolla exceeding narrow portion.
Flowering - August - October.
Habitat - Wet prairies, streambanks, pond margins, fens, mesic forests.
Origin - Native to the U.S.
Other info. - This common species is found in wet areas across most of the state. The shape of the leaves and the promient venation on their lower surfaces are good clues for identification.
Photographs taken at Robertsville State Park, Franklin County, MO, 10-25-2010, and at Weldon Spring Conservation Area, St. Charles County, MO, 10-12-2015 (SRTurner).