No. 14.] FLOWERING PLANTS AND FERNS. 391 



Rare. Waste ground: Southington (Weatherby & Bis- 

 sell), Fairfield (Eames). Aug. Introduced from the West, 

 The rhizome is medicinal. 



IVA L. Marsh Elder. Highwater-shrub. 

 Iva oraria Bartlett (of the coast). 



Iva frutescens of Gray's Manual ed. 6, not L. 

 Highwater-shrub. 



Common on salt marshes and seashores. July — Sept. 



Iva xanthifolia Nutt. (having leaves like Xanthium, the Clot- 

 bur). 



Rare. Waste places: Naugatuck (A. E. Blewitt), Bridge- 

 port (Eames), New Milford (E. H. Austin). July — Sept. 

 Introduced from the West. 



AMBROSIA L. Ragweed. 

 Ambrosi^ bidentata Michx. (two-toothed). 



Rare. Bridgeport, in waste ground (Eames). Sept. 

 Fugitive from the West. 



Ambrosia trifida L. (three-cleft). 

 Great Ragweed. 



Moist places and alluvial flats. Usually rare; but local, 

 frequent or common along the larger rivers and in south- 

 western Connecticut. Aug. — Sept. 



The var. integrifolia (Muhl.) Torr. & Gray (having 

 entire leaves) is occasional with the typical form. 



A coarse and unsightly weed. 



Ambrosia artemisiifolia L. (having leaves like Artemisia, the 



Wormwood). 

 Ragweed. Hog-weed. Bitter-weed. Roman Wormwood. 



Common. Open places, especially in waste and cultivated 

 ground. July — Sept. 



A troublesome andj)ernicious weed in all soils. Its pollen 

 is said to cause hay fever. The plant is medicinal. 



XANTHIUM L. Clotbur. Cocklebur. 

 Xanthium spinosum L. (spiny) . 

 Prickly or Spiny Clotbur. 



