Compositaceae 411 
N. Leaves with scattered fine white-resinous dots. EF. 
A. atomifera Pip. 
NN. Leaves not resinous dotted. EF. 
A. ludoviciana Nutt. 
FF. Leaves entire to cleft or lobed. 
O. Leaves glabrous or very nearly so on both sides. 
P. Herbage sweet-aromatic; 4—8 dm. high; branches not drooping; heads 
30—60-flowered. E. A. aromatica Nels. 
PP.  Herbage not sweet-aromatic; 8—16 dm. high; branches drooping; heads 
15—20-flowered. E. A. dracunculoides Pursh 
f OO. Leaves white-tomentose at least beneath. 
; Q. Involucre persistently white-tomentose. (See MM.) 
QQ. Involucre glabrous to pubescent but green, not tomentose. 
R.  Involucre cylindric; plant 9—1I5 dm. high. W: (A. subsdorfii.) 
. A. heterophylla Nutt. (Golden-rod Sage) 
RR. _ Involucre campanulate. 
S. Plant about 10 dm. high; involucre green. W. C. E. 
A. tilesii Ledeb. 
SS. Plant 3—6 dm. high; involucre gray-brown. E. 
A. lindleyana Bes. 

: 
‘ 
J 
: 
SENECEAE (ARNIcA TRIBE)—Herbs or shrubs. Heads rayless or radiate; 
involucre-bracts mostly in 1—2 series, usually equal, rarely scarious; receptacle naked 
(except sometimes hairy in Arnica). Anthers without tails at base tho often sagittate. 
Style-branches of perfect flowers usually truncate or obtuse, without appendages at tip 
or with short ones. Pappus of capillary bristles but often deciduous; bristles many, smooth 

3 to plumose. 
2 A. Herbs. 
Fi B. Most of the leaves on each plant opposite. ARNICA (p. 412) 
* BB. Leaves alternate or all basal. 
; C. Leaves all basal. 
% D. Scapes densely large-bracted; leaves wider than lanceolate, often more than 
. 10. cm. long; flowers white or pinkish. PETASITES (p. 412) 
4 DD. Scapes naked; leaves linear to oblanceolate, 2.5—-10 cm. long; flowers 
: yellow. RAILLARDELLA (p. 412) 
CC. Some leaves on the stem. 
E. Heads radiate. 
F. Annual; receptacle conic. CROCIDIUM (p. 413) 
FF. Perennial; receptacle flat. SENECIO (p. 414) 
EE. Heads rayless. 
G. Heads 4—10-flowered. 
H. Leaves entire, 12.5 cm. long; heads about 10-flowered. 
LUINA (p. 414) 
HH. Leaves coarsely dentate, 5—-25 cm. long; heads 4—6-flowered. 
RAINIERA (p. 414) 





oie ee ee 
GG. Heads more than |0-flowered. 
I. Leaves palmately 5—9-lobed or -cleft or -parted, palmately veined. 
CacALIopsis (p. 413) 
II. Leaves entire to pinnately compound, not palmately veined. 
SENECIO (p. 414) 
AA. Shrubs. TETRADYMIA (p. 414) 
