(92) 



6. G. PUEPUEEUM L. Bristles of pappus 

 united at the base into a ring. It. Near salt 

 marshes. Common. Summer. 



Tribe III. AMBBOSLE. 



Anthers of or <3 flowers distinct, not syn- 

 genetic. Style abortive, truncate. Corolla of 

 ? flowers rudimentary or 0; pappus 0. 



21, IvaL, 



Necessaria. Superflua. Headoo-flowered; S 

 or flowers oo, tubular, 5-lobed; ? flowers few, 

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

 Paleae of the receptacle linear. It. 



1. I. AXILLAEIS. Pursh. Near the seacoast. 

 Summer. 



22, Ambrosia DC. RAGWEED. 



Monoecious. $ 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. AETEMISI^FOLIA L. Leaves all bipin- 

 natifid. 0. Cultivated grounds. Summer. 



2. A. PSILOSTACHYA DC. Upper leaves pin- 

 natifid, lower bipinnatifid. It- Cultivated 

 grounds. Summer. 



