Compositaceae 387 
N.  Bracts of the involucre equal or nearly so, not distinctly shorter outward. 
O. Involucre-bracts closely appressed, their larger portion coriaceous. E. 
A, elmeri Pip. 
OO. Involucre-bracts loose, their larger portion herbaceous. 
P. Stem-leaves clasping or auriculate, scarcely reduced upward on the 
stem, few. C. E. (A. canbyi; A. foliaceous apricus; A. apricus; A. 
frondeus; A. burkei; A. foliaceous frondeus.) 
A. foliaceous Lindl. 
PP. Stem-leaves sessile but not auriculate nor clasping, either small or 
else reduced upward on the stem, many. 
Q. At least the outer involucre-bracts leaf-like and merging into the 
leaves. 
R. Leaves entire. E. 
A. eatoni How. 
RR. Most of the leaves serrate near their middle. E. 
A. douglasii Lindl. 
QQ. _Involucre-bracts not at all leaf-like; leaves all entire. 
S. None of the involucre-bracts recurved. E. 
A. hendersoni Fer. 
SS. Some of the involucre-bracts recurved. E. 
A. proximus Gr. 
NN. Bracts of the involucre plainly unequal, shorter outward. 
T. Involucre-bracts closely appressed, their greater portion coriaceous; leaves 
entire. E. (A. geveri.) 
A. laevis geyeri Gray 
TT. Involucre-bracts loose, their greater portion herbaceous. 
U.  Stem-leaves auriculate or clasping, scarcely reduced upward on the 
stem, few. (See P.) 
UU. Stem leaves sessile but not auriculate nor clasping (except possibly 
A. fremonti), either small or else reduced upward on the stem, many. 
V. Some of the involucre-bracts recurved. (See QQ.) 
VV. AIl of the involucre-bracts erect or ascending, not recurved. 
W.  Involucre-bracts lanceolate or linear, their tips acute in most. 
X. Most of the leaves linear, serrulate. C. E. (A. occidentalis 
intermedius. ) A. occidentalis Nutt. 
XX. Most of the leaves lanceolate or still wider. 
Y. Leaves not at all clasping at base, entire or serrulate. E. 
A. meritus Nels. 
YY. Leaves half-clasping at base, entire. C. E. 
A. fremonti Gray 
WwW. Involucre-bracts spatulate, their tips rounded. U. 
A. chamissonis Gray 
FF. Heads less than | cm. wide; leaves entire. 
Z. Rays purple or clear blue; involucre turbinate. E. (Apparently A. cordalenus.) 
A. amethystinus Nutt. (Amethyst Aster) 
ZZ. Rays usually white; involucre campanulate. 
a. Involucre-bracts obtuse or mucronate. 
b. Plant rough-pubescent or scabrous; involucre-bracts pubescent. E. 
A. multiflorus Ait. (Wreath Aster) 
bb. Plant not rough tho somewhat pubescent; involucre-bracts glabrous. W. 
E. A. hallii Gray 
aa. Involucre-bracts acute. E. A. oreganus Nutt. 
ae doy 
