Thistle Family. 85 



stein: scales ovate, tapering' into long and spreading points;' achenes broadly 

 winged. Prairies; July; frequent throughout the state. 



S. terebinthiriaeeum Jacq. Stem 4-10 feet high, branched, scaly, gla- 

 brous or nearly so; leaves basal, large, ovate,* 'long-petioled, apex acute, base 

 cordate, 'both sides rough, sharply dentate; heads many; achenes obovate, 

 narrowly winged. Prairies anddry woods; reported fromlowa. 



*■* Stems square; leaves or their pet'mle-bases conitate-perfoliate. 



S. perfoliatum L. Cup-plant. Stem square; 4-7 feet high, often branched 

 above; leaves large, thin, ovate, rough, remotely-toothed, opposite or in 3's, 

 their bases connate, forming a cup around the stem; lower leaves wing- 

 petioled;- bases of ■ petioles dilated and connate; 'heads corymbose, on long 

 peduncle's; scales ovate, achenes winged. Moist soil; July-August; frequent 

 throughout the state. < ' • 



* * * Stem* terete or slightly 4-an'jlcd; leaves opposite or whorleil. 



S. integrifolium Mx. Stem 4-anglefl and grooved, 2-4 feet high, smooth 

 or scabrous; leaves opposite or uppermost alternate'.' ovate-lanceolate, roiigh- 

 pubescent or smooth, entire, rigid, sessile, - bases' cordate," partly' clasping; 

 heads short-pedilneled, in a' close corymb; achenes broadly winged. Prairies, 

 roadsides, and open woods. July- August: frequent throughout the state. 



S. trifoliatum ' L. Stem 4-7 'feet high, glabrous, sometimes glaucous; 

 leaves lanceolat'e'or'oblong-lah'ceolate, the 'middle ones in whorls' of 3 or 4, 

 the uppermost opposite. acuminate 1 , ' narrowed at' the "base, rough above, gla- 

 brate beneath, short-petioled. entire or somewhat' denticulate; heads several 

 or many; achenes rather broadly winged. Woods; reported from Winnebago 

 and Clinton counties.' " '• 



PARTHENIUM L. Perennials, 'with alternate leaves, and' corymbose 

 heads. Rays 5; ligules white, short, obcordate';' fertile; disk-flowers many, 

 sterile. Involucre hemi'spherical; scales in 2 series, ovate or roundish.' Re- 

 ceptacle conical, chaffy. Achenes compressed, crowned with 2 teeth and the 

 remains of the corolla.' ' 



P. integrifoMum L. Prairie Dock. Stem 1-4 feet high, rough-pubescent, 

 mostly simple;' radical 1 or lower leaves long-petioled; ample.' ovate, crenate- 

 toothed, coriaceous, upper sessile: 1 heads ttiany. Upland soil; June-Septem- 

 ber: frequent; more common in the eastern and southern counties; Winne- 

 shiek, Allamakee, Fayette,' Dubuque, Muscatine, Johnson, Henry, Appanoose? 

 Decatur, Ringgold, and'Fremont couuties. ' ' 



ECLIPTAL. 'A rough' annual, with opposite leaves.' and' small solitary 

 many-flowered heads. Ray's short, white, numerous, fertile; diskVflowers 

 perfect, 4-toothed, fertile. Involucral scales in 2 rows, ovate-lanceolate, 

 foliaceous. Receptacle flat, with bristle-like chaff Pappus wanting or of 

 2-4 teeth or short awns. Achenes thick, in the rays mostly 3-sided,' in the disk- 

 flowers compressed, more or less margined:" 



E. alba L. Hasskarl. Stem procumbent or ascending, 1-3 feet high.:'ap- 

 pressed-pubeseent; leaves mostly sessile, lanceolate or oblong, tapering both 

 ways, sparingly serrate; rays scarcely exceeding the disk. River banks; 

 July-August; infrequent; Johnsdn. Linn, Muscatine, and Lee counties. 



hjELIOPSIS Pers. Perennials, with opposite petioled 3-nerved leaves, and 

 yellow flowers. Involucre short, of 2 or 3 rows of imbricated subequal scales. 

 Rays 10 or more, fertile. Receptacle conical, with linear chaff. Pappus cor- 

 oniform,'of 2-3 teeth; or wanting. ' Achenes truncate, smooth, 4-sided. 



r]. scabra Dunal. Rowjh Ox-eye. Stem 2-4 feet high, somewhat pubescent '' 



