Plants 50-100(-200) cm. Leaves: basal blades ± elliptic, mostly 15-40 cm × 100-200+ mm (bases decurrent onto strongly ribbed petioles, margins callose-denticulate, otherwise entire, abaxial faces velvety-woolly, adaxial thinly hairy); cauline blades ovate or elliptic to lanceolate, 10-30 cm × 45-120 mm, bases cordate, clasping, margins serrate. Involucres (20-)30-40 mm diam. Outer phyllaries ovate, oblong, or ± deltate to lanceolate, 12-20(-25+) × 6-8(-20+) mm (abaxially velvety-hairy); inner phyllaries progressively narrower, less hairy, more scarious. Ray florets (15-)50-100+; corolla laminae (10-)20-30+ mm. Disc corollas 9-11 mm. Cypselae 3-4 mm, glabrous; pappi of (40-)50-60 basally connate, barbellate bristles or setiform scales 6-10 mm. 2n = 20.
Flowering mid-late summer. Roadsides, waste places, streamsides; 0-300(-600+) m; introduced; B.C., Man., N.B., N.S., Ont., P.E.I., Que.; Calif., Conn., Del., Ill., Ind., Iowa, Ky., Maine, Md., Mass., Mich., Minn., Mo., N.H., N.J., N.Y., N.C., Ohio, Oreg., Pa., R.I., Tenn., Utah, Vt., Va., Wash., Wis.; Europe; introduced, Asia and beyond.
Inula helenium is widespread in the Old World.
This plant has medicinal qualities and was commonly cultivated by the pioneers. It has escaped in all parts of the state to roadsides, pastures, and open woodland.
Coarse perennial herb to 2 m, the stem finely spreading-hairy; lvs irregularly and shallowly dentate, densely velvety-woolly beneath, sparsely spreading-hairy or subglabrous above, the lower long-petiolate and elliptic, with blade to 5 נ2 dm, the upper becoming ovate, sessile and cordate-clasping; heads few, pedunculate, large, the disk 3-5 cm wide, the invol 2-2.5 cm; outer bracts broad, herbaceous, densely short-hairy; inner bracts narrow, subscarious, glabrous; rays numerous, slender, 1.5-2.5 cm; achenes glabrous, columnar and ±distinctly quadrangular, multistriate; pappus-bristles united at base, often in groups; 2n=20. Intr. from Europe; cult., escaped, and sparingly naturalized in moist or wet disturbed sites. May-Aug.
Gleason, Henry A. & Cronquist, Arthur J. 1991. Manual of vascular plants of northeastern United States and adjacent Canada. lxxv + 910 pp.
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