Home Flora of Missouri
Home
Name Search
Families
Volumes
Silphium integrifolium Michx. Search in The Plant ListSearch in IPNISearch in Australian Plant Name IndexSearch in NYBG Virtual HerbariumSearch in Muséum national d'Histoire naturelleSearch in Type Specimen Register of the U.S. National HerbariumSearch in Virtual Herbaria AustriaSearch in JSTOR Plant ScienceSearch in SEINetSearch in African Plants Database at Geneva Botanical GardenAfrican Plants, Senckenberg Photo GallerySearch in Flora do Brasil 2020Search in Reflora - Virtual HerbariumSearch in Living Collections Decrease font Increase font Restore font
 

Published In: Flora Boreali-Americana (Michaux) 2: 146. 1803. (Fl. Bor.-Amer.) 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

 

Export To PDF Export To Word

2. Silphium integrifolium Michx. (rosinweed)

Pl. 289 d; Map 1227

Plants with short, stout rhizomes. Stems 40–200 cm long, solitary or more commonly appearing clustered, more or less circular in cross-section (often finely many-angled), glabrous or moderately to densely pubescent (variously velvety to roughened) with relatively short (mostly 0.1–0.5 mm), slender to stout hairs, if glabrous then sometimes strongly glaucous. Leaves usually relatively thick and sometimes somewhat leathery, the upper surface glabrous or sparsely to strongly roughened, the undersurface glabrous or moderately to densely roughened or hairy with short, sometimes pustular-based hairs, when glabrous both surfaces sometimes moderately to strongly glaucous. Basal and lowermost stem leaves absent or withered at flowering, with a winged, more or less petiolar base, the bases slightly expanded and somewhat clasping or wrapped around the stem, the blade 7–15 cm long, ovate to elliptic-ovate or narrowly ovate, unlobed, tapered to a usually sharply pointed tip, tapered at the base, the margins entire or finely to occasionally coarsely toothed and usually with minute, more or less appressed hairs. Stem leaves somewhat reduced toward the tip of the stem, opposite (rarely alternate or in whorls of 3), 3–17 cm long, sessile, lanceolate to ovate, broadly ovate, or somewhat heart-shaped, angled to tapered or more commonly rounded to shallowly cordate at the base, sometimes clasping the stem (but not perfoliate), angled or tapered to a sharply pointed tip. Inflorescences loose, open clusters or panicles, rarely of solitary heads, the heads long-stalked to short-stalked or nearly sessile. Involucral bracts 25–38, 10–22 mm long, elliptic to ovate, spreading at the sharply pointed tip, the surfaces glabrous or moderately to densely short-hairy, sometimes also with stalked and/or sessile glands, the margins glabrous or more commonly with short, ascending to spreading hairs. Receptacle 1.5–2.5 cm in diameter. Ray florets (17–)20–35, the corolla 20–50 mm long. Disc florets numerous, the corolla 4.5–5.5 mm long, slightly shorter than or extending slightly beyond the tips of the chaffy bracts. Fruits 8–12 mm long, the surfaces glabrous or inconspicuously but densely hairy, the angles with relatively broad, lighter wings, each wing rounded to somewhat angled at the tip, the fruit usually with a narrowly U-shaped apical notch. 2n=14. July–September.

Scattered nearly throughout the state (Wyoming to New Mexico east to Michigan and Alabama; Canada). Upland prairies, loess hill prairies, openings of mesic to dry upland forests, savannas, tops of bluffs, glades, banks of streams and rivers, and rarely margins of ponds and lakes; also pastures, edges of crop fields, ditches, railroads, and roadsides.

Apparent hybrids between S. integrifolium and S. perfoliatum have been collected in Bates and Warren Counties and are to be expected sporadically at other sites where the two putative parents grow in proximity.

 

Export To PDF Export To Word Export To SDD
Switch to indented key format
1 1. Stems and leaves not glaucous; leaf blades with the undersurface roughened, hairy, or rarely glabrous; involucral bracts with the outer surface and margins hairy ... 2A. VAR. INTEGRIFOLIUM

Silphium integrifolium Michx. var. integrifolium
2 1. Stems and often also the leaves glaucous; leaf blades with the undersurface glabrous or sparsely to moderately hairy only along the midvein; involucral bracts with the outer surface glabrous, the margins sometimes minutely hairy ... 2B. VAR. LAEVE Silphium integrifolium var. laeve
 


 

 
 
© 2024 Missouri Botanical Garden - 4344 Shaw Boulevard - Saint Louis, Missouri 63110