384 Compositaceae 
several series, tips often herbaceous or foliaceous; receptacle flat or convex. Ray-flowers 
none or not yellow, in | series. Disk-flowers yellow, often changing to purple, perfect. 
Pappus of capillary bristles; bristles many, in | whorl (or 2 in IONACTAE), often un- 
equal, scabrous or barbellate. Akenes usually flattish, glabrous or hairy. (Gk. aster—= 
a star; referring to the radiate heads of most species.) 
A. Plants acaulescent, 0.5—-4 dm. high, perennial; leaves all basal and entire, nar- 
rowly spatulate to subulate, grass-like, 2.525 cm. long. 
OREASTRAE (p. 384) 
AA. Plants leafy-stemmed, mostly taller, often annual or biennial; leaves often not 
entire, often wider, not grass-like. 
B. Involucre-bracts in more than 5 series, their tips spreading; rays none or blue 
or purple; leaf-lobes or teeth mucronate or bristle-tipped or none. 
MACHAERANTHRAE (p. 384) 
BB. Involucre-bracts in 1—5 series, their tips erect or spreading; leaf-lobes or 
-teeth not mucronate nor bristle-tipped, often none. . 
C. Plants 0.5—3 dm. high, perennial, alpine; leaves 5-25 mm. long, linear 
or linear-oblong, entire or serrulate-scabrous; rays violet; involucre-bracts not 
herbaceous-tipped. IONACTAE (p. 385) 
CC. Plants mostly taller; leaves mostly longer, often wider; involucre-bracts herba- 
ceous or purple-tipped. 
D. Involucre-bracts dry, chaffy, closely appressed, often purple-tipped, the mid- 
vein keeled or prominent. EUCEPHALAE (p. 385) 
DD. Involucre-bracts green at least at the tip, often spreading at tip, the mid- 
vein neither keeled nor prominent. ' 
E. Rays in more than | series, about 2 mm. long; leaves linear-spatulate, 
entire, 25 mm. or less long; plant annual. BRACHYACTAE (p. 386) 
EE. Rays in | series, more than 2 mm. long; leaves various; plant peren- 
nial. EUASTERAE (p. 386) 
Subgenus OREASTRAE—Perennial; scapes somewhat bracted, in ours 35 cm. 
or less high and simple. Leaves all basal, entire; in ours spatulate or narrower, grass- 
like, 2.525 cm. long. Heads radiate, solitary; involucre-bracts linear (ours), nearly 
equal, in about 2 series. Ray-flowers purple, 1—2 cm. long (ours). Akene hardly 
flattish, distinctly 5—8-ribbed, somewhat hairy (ours). Pappus brownish, barbellate, 
deciduous. 
A. Plant 5—10 cm. high; leaves veinless, obtuse, 2.57.5 cm. long; akenes glabrous 
below, hirsute near tip. C. E. (Oreastrum alpigenum. ) 
A. alpigenus Gray 
AA. Plant 20—35 cm. high; leaves l-veined, acute, 5—-25 cm. long; akenes vil- 
lous. U.C. (Oreastrum andersoni.) 
A. andersoni Gray 
Subgenus MACHAERANTHERAE—Ours biennial or perennial; stems leafy, — 
branched. Leaves entire to pinnatifid: teeth or lobes bristle-tipped. Heads radiate or 
rayless, large; involucre-bracts canescent or glandular, linear, rigid, somewhat keeled; 
their tips herbaceous, spreading or recurved. Akene turbinate’ or wedge-shaped, often 
flat, pubescent or silky, few-veined on the faces. Pappus scabrous. 
A. Heads rayless. U. (Machaeranthera eradiata. ) 
oh A. eradiatus (Gray) 
AA. Heads radiate. 
B. Inner involucre-bracts not bristle-tipped. 
tage a 
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