BOTANY OF LA SALLE COUNTY. 93 



shining', dry; florets Y. Pastures and woods. 

 POLYMNIA. P. Leaf Cup. Tall branching- 



sticky-hairy, strong- scented herbs. 

 P. Canadensis. Leaves thin, lower pinnate lobed, 

 upper triang-ular-ovate; heads small, W. Y. 2 to 

 5 ft. Woods, becoming- more common. 

 Jh. P, Uvoedalia. Lower leaves palmately lobed on 



wing-ed petiole, outer scales larg-e 4 to 10 ft. 

 SILPHIUM. P. Rosin Weed. Tall, roug-h resen- 

 ous-juiced plants with larg-e heads and palish 

 Y., flowers. J. Aug-. Seeds flat, wing-ed. 

 S. laciniatum. Compass Plant. Hairy leaves larg-e, 

 pinnately parted, the segments lobed. 3 to 10 ft. 

 S. terebinthinaceum. Prairie Dock. Leaves large, 

 cordate, rough; stem slender, smooth, nearly 

 . leafless. 4 to 12 ft. 

 S. trifoliatum. Stem smooth; leaves in whorls of 



3 to 4 upper opposite. 3 to 4 ft. 

 S. integrifolium. Stem rigid 4 ang-ular, grooved; 



leaves, opposite, rigid. 



S. perfoliatum. Cup Plant. Leafy, leaves united 

 at base so as to form a cup, larg-e, ovate, 

 coarse toothed . 

 PARTHEN IUM. Heads small, woolly, W. Rays 5, 



very small, W. 



P. integrifo Hum. Leaves large ovate, crenate; 



lower lobed; dark G. Heads in small corymbs. 



IVA. A. Marsh Elder. Heads small in long-, slen- 



der spikes. 



I. xanthifolia. Leaves mostly opposite, hoary, 

 roug-h, broad-ovate, toothed. 3 to 5 feet. Otta- 

 wa. Has recently appeared here. 



AMBROSIA. A. Ragweed. Horse Weed. Coarse 

 weeds. 



