Jones: Flora of Illinois, 152. Compositae 259 



Tribe 7. Heliantheae 

 20. PoLYMNiA L. — Leafcup 



I.Rays white, inconspicuous, 2-5 mm. long; leaves pinnately lobed; achenes 

 3-5 mm. long, angular; woods, common. June-Nov P. canadensis L. 



I.Rays yellow, 1.5-2 cm. long; leaves palmately lobed; achenes 6-8 mm. long, 

 black, flattened; woods and thickets, s. 111. July-Sept P. uvedalia L. 



21. SiLPHIUM L. 

 1. Stem 1-3 m. tall, leafless or nearly so; leaves large, cordate, dentate, long- 



petioled; prairie soil, common. July-Sept. Prairie-dock 



S. terebinthinaceum Jacq. 



1. Stem leafy throughout. 



2. Leaves pinnately parted, large, alternate; prairie soil, common. July-Aug. 



Compass-plant S. laciniatum L. 



2. Leaves toothed or entire, chiefly opposite. 



3. Leaves merely sessile, 7-10 cm. long; stem nearly terete; prairie soil, often 

 along railroads, common. July-Aug. [^. integrijolium var. deamii 

 Perry]. Occasional plants with some of the leaves whorled have been 

 mistaken for S. trifoliatum L., which is not known to occur in III. 



Rosin-weed S. integrifoliion Michx. 



3. Leaves connate-clasping, perfoliate, 20-60 cm. long; stem sharply 4- 



angled; alluvial soil, common. July-Aug. Cup-plant 



S. perfoliatum L. 



22. Parthenium L. 



P. integrijolium L. American Feverfew. Prairie soil, common. July-Sept. 



23. Heliopsis Pers. 



H. helianthoides (L.) Sweet. Open woods, and along roads, common. 

 July-Aug. [H. scabra Dunal] 



24. Eclipta L. 

 E. alba (L.) Hassk. Shores, sloughs, and fields, throughout III., except the 

 n. counties. July-Sept. 



25. RuDBECKiA L. — Coneflower 



1. Peduncles glabrous; disk greenish yellow; rays 2.5-5 cm. long, soon droop- 

 ing; lower leaves pinnately parted, the upper 3-lobed or entire; stem 1.5- 



3 cm. tall, glabrous; alluvial soil, common. July-Sept. Goldenglow 



R. laciniata L. 



1. Peduncles more or less pubescent; disk brown or purple; stem 30-150 cm. 



tall. 



2. Chaff of the receptacle acuminate, glabrous; lower leaves, or some of 



them, 3-lobed or 3-parted, the upper lanceolate, entire or serrate; rays 



8-12, orange-yellow, 1.5-2.5 cm. long; woods, locally throughout III. 



Aug.-Oct. Brown-eyed Susan R. triloba L. 



2. Chaff obtuse or acutish, puberulent toward the tip. 



