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Published In: Flora Americae Septentrionalis; or, . . . 2: 575. 1814[1813]. (Fl. Amer. Sept.) Name publication detailView in BotanicusView in Biodiversity Heritage Library
 

Project Name Data (Last Modified On 8/11/2017)
Acceptance : Accepted
Project Data     (Last Modified On 7/9/2009)
Status: Native

 

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8. Rudbeckia subtomentosa Pursh (sweet coneflower)

Pl. 288 c, d; Map 1224

Plants perennial, with fibrous roots and stout rhizomes. Stems 50–200 cm long, moderately to densely pubescent with short, spreading hairs, at least above the midpoint, not glaucous. Leaves mostly (or occasionally only the lowermost leaves) deeply 3-lobed or deeply divided, mostly angled or tapered at the base, only slightly expanded at the base and inconspicuously wrapping around the stem, the margins otherwise sharply and finely to coarsely toothed, the surfaces (especially the undersurface) moderately to densely pubescent with short, spreading, minutely pustular-based hairs, often also minutely gland-dotted, moderately to strongly roughened to the touch, green to grayish green when fresh. Basal and lowermost stem leaves often absent at flowering, long-petiolate, the blade 15–30 cm long, 30–100 mm wide, ovate to broadly ovate or elliptic in outline, the lobes ovate to narrowly elliptic or lanceolate, tapered to a sharply pointed tip. Median and upper stem leaves short- to long-petiolate, the uppermost leaves occasionally sessile, the blade 2–20 cm long, 1–120 mm wide, the unlobed leaf blade or the lobes of a divided blade lanceolate to ovate to elliptic, tapered to a sharply pointed tip. Inflorescences mostly appearing as loose, open clusters or leafy panicles. Involucral bracts 15–25, 5–15 mm long, lanceolate to nearly linear, the outer surface and margins densely pubescent with short, usually minutely pustular-based hairs. Receptacle 10–17 mm long, 8–16 mm in diameter, usually hemispherical at the start of flowering, then elongating somewhat and becoming more or less conical. Chaffy bracts subtending only the disc florets, shorter than to nearly as long as the disc florets (including the corolla), angled to a short, usually sharply pointed tip, the outer surface and margins with dense, short, often somewhat matted hairs, dark purple toward the tip or rarely dull greenish yellow (see discussion below). Ray florets 12–20, the corolla 20–40 mm long, usually relatively slender, spreading or slightly drooping at flowering, yellow to orangish yellow, the outer surface sparsely short-hairy and moderately minutely gland-dotted. Disc florets numerous, the corolla 3.0–4.5 mm long, yellowish green toward the base (or rarely throughout), normally dark purple to purplish brown toward the tip, the lobes spreading to curled downward at flowering. Stigma lobes relatively short and usually sharply pointed at the tip. Pappus a minute rim or crown. Fruits 2.0–3.5 mm long. 2n=38. July–October.

Scattered nearly throughout the state (Kansas to Texas east to Michigan and Alabama, possibly also North Carolina; introduced in New England). Bottomland forests, edges of mesic upland forests, upland prairies, banks of streams and rivers, margins of ponds and lakes, and fens; also pastures, ditches, railroads, and roadsides.

Rare plants with the disc corollas and chaffy bracts dull yellow to yellowish green have been called R. subtomentosa f. craigii (Sherff) Fernald. This form originally was described based on plants collected in 1910 by Moses Craig in St. Louis County. It may still be known only from the original site, where plants historically grew with more typical plants having purple disc florets and chaffy bracts.

 


 

 
 
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