mi COMrCSlTAE. 



frequent: Johnson, Muscatine, Story, Decatur, Ringgold, and Taylor counties. 



BIDENS L. Annual herbs, with opposite variously cut or divided leaves, 

 and yellow flowers. Involucre double, the outer usually foliaeeous. Re- 

 ceptacle flat, chaffy. Rays 4-s. neutral, or none. Pappus of 2-4 awns, 

 roughened backward. Achenes slender, quadrangular or flattened parallel 

 with the involucral scales. 



* Plants terrestrial; leaves lanceolate, xerrate, tnnliviiled. rarely lohed. 

 f Rays present, ronxpwuons, sometimes wantimj In IS. cernua. 



B. chrysanthemoides Mx. Stem < >— "3 4 inches high, erector reclining be- 

 low; leaves sessile, lanceolate, tapering both ways, serrate, connate; heads 

 erect; outer involucre shorter than the rays; achenes 2— l-awned. Wet, places; 

 August-September; common; Winneshiek. Johnson. Floyd, Story, Decatur, 

 Winnebago, and Emmet counties; reported from Fayette, Muscatine, and 

 Woodbury counties. (B. laevix (Ci,) 1». S. P.) 



B. cernua U Stem (i— 24 inches high, nearly smooth: leaves lanceolate, 

 sessile, sometimes slightly connate, coarsely serrate; heads nodding-, rays 

 few or none; outer involucral scales longer than the head; achenes usually 

 4-awned. Wet places; July-September; common; Johnson and Decatur 

 counties, reported from Fayette, Scott, Henry, Lee, Story, and Emmet coun- 

 ties. 



t t Rays rudimentary or none. 



B. comosa (Gray) Wiegand. Stem 1-3 feet high, straw-colored; leaves 

 short-petioled, lanceolate, coarsely serrate, petioles broadly margined;, outer 

 involucral scales foliaeeous, 2-4 tiroes as long as the heads; corollas pale 

 greenish yellow, mostly 4-lobed; pappus awns usually 3. Mcist soil; August- 

 September; probably common; Johnson and Decatur counties; reported from 

 Fayette county. {D. cimiuttii comosa Gray). Probably confused with the fol- 

 lowing. 



B. connati Muhl. Swamp Bejijar-ticlix. Stem !-."> feet high, purple: leaves 

 thicker and greener than in the preceding, lanceolate or oblong-lanceolate, 

 coarsely serrate, petioled: involucral bracts not foliaeeous: disk-flowers 

 orange; achenes with 2—1 awns. Wet places; August-September, common; 

 reported from Fayette, Johnson, Henry, and Story counties. 



* * Plants terrestrial leaves nnstly l-:J-parted or dissected. 

 t Rays slmrt, rudimentary, or none. 



B. frondosa h. Beoijar-tlcks Stem 2-4 feet high, branihing. smooth or 

 somewhat hairy; leaves petioled, 3-5-divided. divisions mostly stalked, lanceo- 

 late, serrate; outer involucral scales slender, much longer than the head, 

 ciliate below; rays wanting: achenes with 2 long retrosely barbed awns. 

 Moist ground; July-September; common. 



f f Rays large and amspinnnns. 



B. aristosa (Mx.) Hritton. Stem much branched, l-:3 feet high: leaves 

 thin, pubescent beneath, slender petioled. the lower pinnately :,-T-divided. 

 segments lanceolate, serrate, incised or pinnatifid, upper leaves less divided; 

 involucral bracts glabrous or ciliate, short, tlie outer linear or spatulate, 

 usually ciliate, not exceeding the inner; awns slender. 2, barbed, as long as 

 the achene. Low grounds; August-September; reported from Muscatine and 

 Renton counties, (i'oreopxix arlstosa Mx.) 



B. involucrata (Nutt.) Kritton. Stem l-.l feet high, much branched, 

 minutely pubescent; leaf-segments linear-lanceolate, long-acuminate, incised 

 or pinnatitid; outer involucral bracts linear-lanceolate, hispid and ciliate, 



