(92) 



6. G. PURPUEEUM L. Bristles of pappus 

 united at the base into a ring. — If. Near salt 

 marshes. Common. Summer. 



Tribe III. Ambrosia. 



Anthers of ^ or $ flowers distinct, not syn- 

 genetic. Style abortive, truncate. Corolla of 

 ? flowers rudimentary or 0; pappus 0. 



21. Iva L 



Necessaria. Superflua. Headoo-flowered; ^ 

 or 6 flowers ao, tubular, 5-lobed; $ flowers few, 

 5-dentate. Scales of the involucre 3 to 4, ovate. 

 Palene of the receptacle linear. — 71. 



1. I. AXILLARIS. Pursh. — Near the seacoast. 

 Summer. 



22. Ambrosia DO. Eagweed. 



Monoecious. S head oo-flowered; scales of 

 the involucre united into a cup; receptacle flat, 

 naked; ? head 1-flowered. Scales of the in- 

 volucre united into a cup. Corolla 0. Akenes 

 enclosed in the persistent involucre. 



1. A. ARTEMisi^FOLiA L. Lcaves all bipin- 

 natifid. — 0. Cultivated grounds. Summer. 



2. A. PSiLOSTACHYA DC. Upper leaves pin- 

 natifid, lower bipinnatifid. — U- Cultivated 

 grounds. Summer. 



