26 



VASCULAR PLANTS. 



the scales of the involucre. Involucre 2-seriate. 

 Eeceptacle narrow, naked. Akenes falling off 

 with the embracing scales of the involucre ; 



pappus 0. 



0. flowers inconspicuous. 



16. Psilocarphus, Nutt. 



Necessana. Superflua. Head co-flowered ; 

 $ flowers few, tubular, 5-dentate. 9 co-seriate, 

 filiform, each wrapped in a palea. Scales of 

 the involucre few, scarious ; receptacle convex, 

 externally paleaceous, naked in the centre; 

 akenes enveloped in the paleaa ; pappus 0. 

 0. flowers inconspicuous. 



17. Stylocline, Nutt. 



Necessaria. Superflua. Head co-flowered; 

 $ flowers tubular, few ; 9 flowers co-senate, 

 filiform, involucrate by pale* but not enwrap- 

 ped. Pappus a few caducous bristles. 

 0. flowers inconspicuous. 



18. Evax, Gaertn. 



Necessaria. Superflua. Head oo-flowered; 

 $ flowers tubular, few ; 9 flowers co-seriate, 

 filiform. Scales of the involucre few 1— 2-seriate, 

 scarious. Eeceptacle elongate (like the axis of 

 a spike), paleaceous externally, naked in the 

 centre with the $ flowers Pappus 0. 

 0. flowers inconspicuous. 



