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Tomentose or glabrous, with peduncles 8–12´ long; leaves finely dissected, with short filiform segments; involucels gamophyllous, 5–7-cleft, with conspicuously hairy margins; flowers yellow; fruit broadly oblong, glabrous, with wings half as broad as the body, and prominent dorsal ribs; oil-tubes 1–3 in the intervals.—Minn. to Tex.

Fruit dry, twin, of 2 indehiscent 1-seeded carpels.—A slender procumbent herb, with square stems, lanceolate pungent leaves in whorls of 4–6, and small subsessile blue or pinkish flowers surrounded by a gamophyllous involucre.

Gamophyllous, formed of united leaves.