380 Compositaceae 
AA. Heads radiate. 
D. Stem glabrous. 
E.  Involucre-bracts somewhat foliaceous; leaf-teeth spinulose-tipped or none. 
PyRROCOMAE (p. 380) 
EE.  Involucre-bracts papery, not foliaceous; leaf-teeth not spinulose-tipped or 
none. 
F. Heads not in corymbs, many-flowered; akenes densely hairy. 
STENOTAE (p. 381) 
FF. Heads in corymbs, few- to several-flowered; akenes glabrous. 
PETRADORAE (p. 382) 
DD. Stem hairy. 
G. Involucre-bracts foliaceous at least at tip. 
H. Leaves coriaceous; involucre-bracts veinless; ray-flower 0—25. 
PYRROCOMAE (p. 380) 
HH. Leaves herbaceous; involucre-bracts 1 -veined. 
I. Ray-flowers 2—9; leaves sessile; pappus tawny to reddish; plant not 
viscid nor glandular. MACRONEMAE (p. 381) 
II. Ray-flowers 15—20; leaves petioled; pappus white; plant viscid or 
glandular. TONESTAE (p. 381) 
GG. Involucre-bracts papery at least at margin and tip, not foliaceous, |-veined; 
plants viscid or glandular; ray-flowers 8—12. STENOTAE (p. 381) 
Subgenus SIDERANTHAE—Finely pubescent (ours) ; stems simple, 1—3 dm. 
high (ours). Leaves with spinulose-tipped teeth. Heads rayless, many-flowered; tips 
of all the involucre-bracts somewhat spreading, green, abrupt. Akenes densely silky. 
Pappus white; bristles barbellate. 
A. Plant glandular-pubescent; leaves obovate to oblanceolate; pappus-hairs scabrous. 
E. (Macronema aberrans.) A. aberrans (Nels.) ) 
AA. Plant white-tomentose but not glandular; leaves oblanceolate to lanceolate; pap- 
pus-hairs barbellate. E. (Eriocarpum grindelioides. ) 
A. grindelioides Brit. 
Subgenus PY RROCOMAE—Glabrous to tomentose; stems mostly simple, |—8 
dm. high (ours). Leaves entire or with spinulose-tipped teeth. Heads radiate or ray- 
less, many-flowered ; involucre-bracts veinless, somewhat foliaceous; tips somewhat spread- 
ing. Ray-flowers 0—25 (ours). Akenes glabrous or hairy. Pappus dull-yellow or 
brown or reddish; bristles scabrous to almost plumose. 
A. Rays none or inconspicuous. com 
B. Akenes glabrous; rays either none or hardly exceeding the pappus. FE. (Pyr- 
rocoma carthamoides; Hoorebekia carthamoides; Pyrrocoma cusickti; Hoorebekia 
cathamoides cusichit. ) A. carthamoides Gray ; 
BB. Akenes sparsely hirsute; rays present, plainly exceeding the pappus but incon- 
spicuous. E. (Pyrrocoma racemosa; Hoorebekia racemosa; Pyrrocoma radiata.) 
A. racemosus Torr. 
AA. Rays conspicuous. 
C. Plant glabrous except sometimes in the inflorescence. 
D. Leaves oblong-lanceolate to spatulate, entire to distinctly serrate. E. (Pyr- 
rocoma glomerata; Pyrrocoma arguta; Pyrrocoma paniculata. ) 
A. paniculatus Gray 
DD. Leaves lanceolate to linear, entire. U. E. (Pyrrocoma congesta; Pyrro- 
coma hallii; Hoorebekia hallii.) ; 
A. hallii Gray 
