CARDUACEAE. 359 



31. ERIGERON L. FLEABANE. 



Bracts of the involucre in 1-2 series of almost equal length, not thickened on 



the back. 



Rays inconspicuous, erect or ascending, usually involute and incurved, numer- 

 ous ; often inside them a series of rayless pistillate flowers ; leaves entire. 



I. ACRES. 



Rays conspicuous, spreading, flat ; no rayless pistillate flowers inside. 

 Plant without runners. 

 Perennials. 



Leaves dissected or deeply cleft. II. MULTIFIDI. 



Leaves entire or merely toothed. 



Stems low, less than 2 dm. high, scapiform, usually bearing only one 



head ; stem-leaves usually reduced. 

 Involucres and peduncles villous with many-celled hairs ; bracts 



comparatively broad. III. UNIFLORI. 



Involucres and peduncles hirsute to glandular-puberulent or glabrate, 



not long-villous. IV. RADICATI. 



Stem leafy, 2-10 dm. high, if lower bearing several heads; stem- 

 leaves ample. 

 Stems densely cespitose from a thick tap-root ; heads small ; disk 



rarely over i cm. wide. 



Pappus double ; stem hirsute. V. PUMILI. 



Pappus simple ; stems strigose. VI. DECUMBENTES. 



Stems usually solitary from the ends of distinct (sometimes branched) 



rootstocks ; heads large ; disk over i cm. wide. 

 Bracts loose with reflexed tips ; rays broad ; pappus simple ; lower 



leaves broadly oblanceolate, the upper often reduced. 

 Bracts villous. VII. ELATIORES. 



Bracts glandular-puberulent or glabrous. 



VIII. SALSUGINOSI. 

 Bracts appressed, except the very tips ; rays narrow ; pappus 



double. 



Upper stem-leaves ample, ovate to lanceolate, not much smaller 

 than the lower, which are more or less distinctly 3-nerved ; 

 peduncles usually short, ascending. IX. MACRANTHI. 



Upper stem-leaves reduced, linear-lanceolate ; none of the 

 leaves 3-nerved ; peduncles long and erect. 



X. GLABELLI. 

 Annuals or biennials. 



Stem-leaves not cordate-clasping. 



Stems rather simple with a few large heads ; disks about i cm. or 



more broad. X. GLABELLI. 



Stems much branched, leafy, with numerous small heads ; disk 6-9 



mm. broad. 

 Stems strigose, except at the base ; pappus-bristles of the rays 



usually lacking. XI. RAMOSI. 



Stems and leaves densely short-pubescent with spreading hairs ; 



pappus-bristles of the rays present. 



Annuals ; pappus scant and simple. XIII. BELLIDIASTRA. 



Biennials (rarely perennials) ; pappus double, the outer of short 



subulate squamellae. XIV. DIVERGENTES. 



Stem-leaves broad, cordate-clasping. XII. PHILADEI.PHICI. 



Plants first with a scapiform, naked peduncle, later producing lateral runner- 

 like branches. XV. FLAGELLARES. 

 Bracts of the involucre in 3-4 series, more or less imbricated, thickened on the 



back ; the outer usually successively shorter. 



Achenes terete or nearly so, several-nerved. XVI. CANI. 



Achenes flattened or quadrangular, 2-4-nerved. XVII. CAESPITOSI. 



