(92) 
6. G. purpurEUM L. bBristles of pappus 
united at the base into a ring.—2f. Near salt 
marshes. Common. Summer. 
Tribe III. Amprosiz. 
Anthers of 8 or ¢ flowers distinct, not syn- 
genetic. Style abortive, truncate. Corolla of 
2 flowers rudimentary or 0; pappus 0. 
21, Iva L. 
Necessaria. Superflua. Head o-flowered; ¥& 
or 6 flowers o, tubular, 5-lobed; ¢ flowers few, 
5-dentate. Scales of the involucre 8 to 4, ovate. 
Palex of the receptacle linear.—2,. 
1. I. axitiaris. Pursh.—Near the seacoast. 
Summer. 
22, Ambrosia DO. RaGweEep. 
Moncecious. ¢ head oo-flowered; scales of 
the involucre united into acup; receptacle flat, 
naked; ¢ head 1-flowered. Scales of the in- 
volucre united intoacup. Corolla0. Akenes 
enclosed in the persistent involucre. 
1, A. anremistmrotia L. Leaves all bipin- 
natifid.—©. Cultivated grounds. Summer. 
2. <A. psttostacnoya DC. Upper leaves pin- 
natifid, lower bipinnatifid.—2f. Cultivated 
grounds. Summer. 
