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 1 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 1 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 1 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. Philadelphici. 
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. 
