376 Compositaceae 
CC. Pappus of scabrous capillary bristles; involucre often glandular but then 
not glabrous. 
D. Involucre-bracts in 2—6 vertical rows. CHRYSOTHAMNUS (p. 382) 
DD. Involucre-bracts not in vertical rows. s 
E. Leaves all entire. 
F. Heads only | on a stem. 
G. Involucre glandular; plant 15—-30 cm. high, white-tomentose. 
APLOPAPPUS (p. 379) 
GG. Involucre hairy, not glandular; plant 5—15 cm. high, white- 
puberulent to glabrous. ERIGERON (p. 388) 
FF. Heads more than | on a stem. 
H. Plant white-tomentose; involucre glandular. 
APLOPAPPUS (p. 379) 
HH. Plant not tomentose; involucre rarely glandular. 
I. Involucre-bracts recurved at tip. 
(Machaerantherae) ASTER (p. 383) 
II. Involucre-bracts appressed or erect, not recurved. 
J. Involucre-bracts in 1—3 whorls, herbaceous; annual or bien- 
nial. ERIGERON (p. 388) 
JJ. Involucre-bracts in 3 or more whorls, scarious, often with green 
tips, thin or firm; perennial. 
K. Leaves oblong; plant viscid-pubescent, 1.5—3 dm. high. 
CuHRYSOPSIS (p. 378) 
KK. Leaves ovate-lanceolate; plant glabrous or nearly so, not 
viscid, 6—9 dm. high. (Eucephalae) ASTER (p. 383) 
EE. Leaves or at least the lower ones not entire. 
L. ‘Teeth of the leaves spinulose-tipped. . APLOPAPPUS (p. 379) 
LL. ‘Teeth of the leaves not spinulose-tipped. 
(Machaerantherae) ASTER (p. 383) 
LLL. Leaves or nearly all of them entire. 
- M._ Involucre-bracts recurved at tip. ERIGERON (p. 388) 
MM. Involucre-bracts erect or appressed at tip, not recurved. 
ASTER (p. 383) 
BB. Shrubs, glabrous but sticky; staminate and pistillate heads on separate plants. 
BaccHarIs (p. 391) 
AA. Rays yellow. 
Pappus of scales or rigid awns. 
O. Heads large, 10—25 mm. high, many-flowered; pappus of 2—8 rigid awns; 
involucre-bracts often gummy, often recurved at tip. GRINDELIA (p. 378) 
OO. Heads small, 4—6 mm. high, 2—20-flowered: pappus of 4—14 scales; 
involucre-bracts often gummy, often recurved at tip. GRINDELIA (p. 377) 
NN.  Pappus or most of it of capillary bristles. 
P. Pappus of 2 distinctly different whorls, an inner of scabrous capillary bristles, 
an outer of small scales or bristles. 
Q. _Involucre-bracts in several indistinct whorls, the outer distinctly shorter. 
Curysopsis (p. 378) 
QQ. Involucre-bracts in |—2 indistinct whorls, all about equal. 
ERIGERON (p. 388) 
PP. Pappus of a single whorl of bristles or else the whorls alike when more than 1. 
R. Involucre-bracts not in vertical rows; rays rarely fewer than 5; leaves vari- 
ous; herbs or shrubs. 
S. Pappus-bristles equal or nearly so; heads 3—12 mm. wide. 
SOLIDAGO (p. 378) 
£. 
oid 
i 

