(93) 



23, Franseria Cav. 



Monoecious. $ head co-flowered. Scales of 

 the involucre united into a cup. Palese of the 

 flat receptacle filiform. ? head 1-, sometimes 

 2-4-flowered. Scales, of the involucre united 

 into a cup; if the cup be more than 1-flowered, 

 forming as many cells as there are flowers. 

 Involucre armed with cc rows of spines. Akenes 

 enclosed in the persistent involucre. It. 



1. F. BIPINNATIFIDA Less. Leaves 2-3-pin- 

 nately divided. Sand dunes, San Francisco. 

 Summer. 



2. F. CHAMISSONIS Less. Leaves cuneate to 

 ovate, obtusely serrate, the lower sometimes 

 laciniate. Sand dunes, San Francisco. Sum- 

 mer. 



24, Xanthium Tourn. COCKLEBUR. 



Monoecious. 3 head co-flowered. Scales of 

 the involucre 1-seriate, distinct. Keceptacle 

 cylindrical, paleaceous. ? head 2-flowered. 

 Scales of the involucre united into a cup, armed 

 with hooked spines. Corolla filiform. Akenes 

 enclosed in the persistent involucre. 0. 



1. X. STRUMARIUM L. Leaves green on both 

 sides, scabrous, irregularly serrate. Road- 

 sides. Common. Summer. 



2. X. SPINOSUM L. Leaves whitish beneath, 

 most of them deeply lobed. Waste grounds. 

 Common. Summer. 



