460 



COMPOSITAE. 



VOL. ill. 



series, pistillate, fertile, the ligules numerous, linear. Disk-flowers perfect but sterile, their 

 corollas tubular, 5-toothed, the style undivided. Anthers minutely 2-toothed or entire at the 

 base. Achenes broad, dorsally flattened, 2-winged, notched at the apex. Pappus none, or of 

 2 awns confluent with the wings of the achene. [Greek, from the resinous juice.] 



About 12 species, natives of North America, known as Rosin-weed or Rosin-plant. Type species: 

 Silphium Asteriscus L. 



Stem leafy, the leaves opposite, alternate, or verticillate. 



Leaves, or their petiole-bases, connate-perfoliate ; stem square. 

 Leaves not connate-perfoliate, sessile or petioled. 



Leaves opposite, or the uppermost alternate ; cauline sessile. 



Leaves, or some of them, verticillate in 3's or 4's, petioled. 



Most or all of the leaves alternate, entire or dentate. 



Leaves all alternate, pinnatifid or bipinnatifid, large. 

 Stem leafless or nearly so, scaly above ; leaves basal, large. 

 Leaves sharply serrate to pinnatifid ; achenes obovate. 

 Leaves coars'ely dentate ; achenes suborbicular. 



1. S. perfoliatum. 



2. S. integrifolium. 



3. S. trifoliatum. 



4. .S". Asteriscus. 



5. 5". laciniatum. 



6. S. terebin'.hinaceum. 



7. S. reniforme. 



i. Silphium perfoliatum L. Cup- 

 plant. Indian-cup. Fig. 4421. 



S. perfoliatum L. Sp. PI. Ed. 2, 1301. 1763. 



Stem square, glabrous, or rarely some- 

 what hispid, branched above, or sometimes 

 simple, 4-8 high. Leaves ovate or deltoid- 

 ovate, opposite, the upper connate-perfol- 

 iate, the lower abruptly contracted into 

 margined petioles, all thin, usually scabrous 

 on both sides, or pubescent beneath, coarse- 

 ly angulate-dentate, or the upper entire, the 

 larger 6'-i2' long, 4'-8' wide ; heads com- 

 monly numerous, 2'-$' broad; rays 20-30, 

 about i' long and 2" wide; involucre de- 

 pressed-hemispheric, its outer bracts broad, 

 ovate, ciliolate, spreading or erect ; achenes 

 obovate, emarginate, sometimes 2-toothed. 



In moist soil, southern Ontario to Minne- 

 sota, South Dakota, New Jersey, Georgia, Ne- 

 braska and Louisiana. Naturalized near New 

 York City, and elsewhere escaped from culti- 

 vation. Called also ragged-cup. July-Sept. 



2. Silphium integrifolium Michx. Entire- 

 leaved Rosin-wood. Fig. 4422. 



5". integrifolium Michx. Fl. Bor. Am. 2: 146. 1803. 



5". speciosum Nutt. Trans. Am. Phil. Soc. (II) 7: 341. 

 1841. 



Stem glabrous, rough or sometimes hirsute, co- 

 rymbosely branched above, 2-5 high. Leaves ovate 

 to ovate-lanceolate, acute or acuminate, entire, den- 

 ticulate or remotely dentate, rough above, pubescent 

 or glabrous beneath, those of the stem all closely 

 sessile, often half-clasping but not connate-perfol- 

 iate at the rounded base, 3'-$' long, i'-2' wide; 

 heads usually numerous, i'-2' broad; involucre 

 nearly hemispheric, its outer bracts ovate or ovate- 

 lanceolate, acute, spreading, ciliolate or pubescent; 

 rays 15-25; achenes oval or obovate, 4"-5" long, 

 deeply emarginate. 



On prairies, Ohio to Minnesota, south to Louisiana, 

 Nebraska, Arkansas and Texas. Aug.-Sept. 



