Aquatic and Wetland Vascular Plants of the Northern Great Plains
49. Asteraceae, the Aster Family
18. Vernonia Schreb. -- Ironweed1. Vernonia fasciculata Michx.
Stout, erect perennial 4-12 dm tall, from a thick rootstock; stems single or clumped, often reddish or purplish, glabrous below to puberulent above, especially in branches of the inflorescence. Leaves simple, alternate, short-petioled, lanceolate to ovate-lanceolate, 4-15 cm long, 0.8-4.5 cm wide, smooth to scabrous above, dark-pitted beneath, acute to acuminate, denticulate to serrate, cuneate at the base. Inflorescence corymbiform, the heads usually numerous and crowded in flat-topped clusters; heads discoid; involucres campanulate, 6-9 mm high, the bracts imbricate, green with purple tips, obtuse to subacute, finely villous on the margins; receptacle flat, naked; disk florets all perfect, the corollas purple; style branches slender and tapered, puberulent. Achenes 3-4 mm long, strongly ribbed; pappus of numerous purplish to coppery capillary bristles. Mid Jul--Oct. Wet meadows, stream banks, ditches, flood plains and prairie swales; frequent in the e and c parts, rare in the w; (OH to Man. and Sask., s to MO and n TX).
Northern Great Plains plants are mostly subsp. corymbosa (Schwein. ex Keating) S. B. Jones, which has middle cauline leaves less than 10 cm long and scabrous above, and inner involucral bracts 2-3 mm wide. Entering our range in se SD, c and e NE is subsp. fasciculata, with middle cauline leaves 8-15 cm long, glabrous above or nearly so, and with inner involucral bracts up to 2 mm wide.
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