128 CONTRIBUTIONS FROM THE NATIONAL HERBARIUM. 
PHYSCIA (Schreb.) Ach. 
Thallus foliaceous, repeatedly lobed, lobes mostly narrow; apothecia circular, sessile, 
at times slightly elevated or subpedicellate, lecanorine; spores 8, brown, oblong to 
ellipsoid, bilocular (with us), the epispore thickened; sterigma multiarticular; sper- 
matia short, straight, seldom acicular and bowed. 
KEY TO SPECIES, 
Thallus appressed. 
Thallus white to light gray. 
Sorediate at center. ..........2.-0.....-2000- Oeeeense 3. P. astroidea. 
Not sorediate. 
White beneath. 
Thallus orbicular, laciniate-radiate............ 4, P. crispa. 
Thallus orbicular-stellate...............2.2.. 1. P. stellaris. 
Dark beneath. ........2.22202200.0000.00 2.22 2. P. aipolia, 
Thallus green gray... 2.2.2.2... 0220222222 e eee ee eee 5. P. adglutinata. 
Thallus not appressed, ascending more or less. 
Some shade of gray. 
Broadening at periphery...............2......2.2.---- 8. P. tribacia. 
Not broadening at periphery. 
Hooded at the extremities..........2.020......... 6. P. hispida. 
Not hooded. ...........2.20020000-000002 0c eee eee 7. P. setosa, 
From gray becoming reddish and brown. 
Not pruinose, in color brown. ................-.-2.--- 10. P. obscura, 
Pruinose throughout. 
Thallus sorediate. 
Densely coralloid-sorediate...........2...0.... 9d. P. pulverulenta 
istdtigera. 
Sorediate only on the margin of the lacinie..... 9c. P, pulverulenta 
pityrea. 
Thallus not sorediate. 
Thalline margin(exciple)crowned with lobules. 9b. P. pulverulenta 
- subvenusta, 
Thalline margin not lobulate. 
Laciniz of thallus relatively broad....... 9. P. pulverulenta. 
Lacinize of thallus narrowly linear........ 9a. P. pulverulenta 
angustata. 
1. Physcia stellaris (L.) Nyl. 
Thallus orbiculate-stellate, appressed, whitish to silver gray, glaucescent, beneath 
pale with pale rhizine, KHO+yellow; apothecia sessile and subsessile, numerous; 
disk commonly plane, black or pruinose; thalline margin persistent, generally entire 
(or crenate); epithecium subcontinuous, yellowish gray; thecium colorless, 116 to 120 It 
high; paraphyses rather loosely coherent, the colored tips clavate, not jointed; hypo- 
thecium colorless, milky; asci inflated-clavate, the thickened part reaching the epi- 
thecium; spores ovoid-ellipsoid, steel gray to brown, bilocular, 16 to 25 te long, 10 to 
12 » thick, the lumina round or flat-obcordate; epithecium and thecium blue with 
iodine, KHO—. 
Frequent throughout, on stones, bark, and dead wood, from the plains ascending 
the mountains to an elevation of 2,000 meters. Cosmopolitan. 
2. Physcia aipolia (Ach.) Nyl. 
Thallus stellate, loosely appressed, whitish to gray, glaucescent, epruinose, laciniate, 
the lacinie many-cleft, contiguous and imbricate, narrow, spreading teward the 
periphery and there also dilated, beneath brownish gray and darkening with gray or 
dark rhizinw, the surface and medulla yellow with KHO, Ca(ClO),—; apothecia 
