Key to the System of 



324. Involucral bracts in about two rows of nearly equal 



length. 



Usually herbaceous plants; leaves scattered, some basal; 

 marginal flowers pluriseriate, their corollas narrowly 

 expanding and forming a bluish or whitish ray ; fruits 

 much compressed ; bristlets of pappus in one or two rows, 

 the outer often much shortened. Erigeron. 1351 



Involucral bracts in more than two rows, unequal in 

 length 325 



325. Marginal ligulate flowers mostly pluriseriate. 



Half-shrubs or small shrubs, flowering in an early and then 

 herbaceous state ; leaves scattered ; rows of involucral 

 bracts few or several ; corollas of the marginal flowers 

 forming a whitish or bluish ray ; fruits much compressed ; 

 bristlets of pappus usually in more than two rows. 



Vittadinia. 1353 



Marginal ligulate flowers mostly uniseriate. 



Herbs, shrubs or seldom trees ; leaves scattered, rarely 

 opposite or clustered ; rows of involucral bracts few or 

 several ; corollas of the marginal flowers forming a whitish 

 or bluish ray ; fruits cylindrical or variously compressed ; 

 bristlets of pappus in one or two rows, the outer much 

 shortened. Figure 81. Aster. 1354 



326. Fruits truncated. 



Herbs, never very tall ; involucral bracts of nearly equal 

 height (length) in about two rows; no bracts between the 

 flowers ; ligulate flowers uniseriate ; pappus very short 

 or obliterated. Bracliycome. 1383 



Fruits terminated by a cylindric prolongation. 



Herbs, never very tall ; leaves conspicuously indented ; 

 involucral bracts unequal, in few or several rows ; 

 ligulate flowers uniseriate ; fruits of the central flowers 

 remaining undeveloped. Lagenophora. 1406 



327. Flower-headlets distinct, without a general receptacle 328 



Flower-headlets crowded into a dense cluster on a 

 general receptacle ... 351 



328. Involucral bracts herbaceous ... 329 



Involucral bracts scarious ... ... .... ... 337 



