272 35. GYROPHORACEAE [134. Gyrophora 



and below, that of the lower side especially well developed; apothecia im- 

 mersed to shortly stalked, black or blackish, usually thrown into closely packed, 

 elongated or roundish folds, each fold apparently a shortly stalked apothecium 

 as seen in section, the whole apothecium surrounded by a black, proper exciple; 

 hypothecium brownish to black; paraphyses loosely arranged, usually un- 

 branched; asci usually clavate; spores 8, hyaline, non-septate. 

 The algal host is Pleurococcus. 



A. Thallus usually bearing rhizoids below 



B. Thallus black below, more or less covered with rhizoids 

 C. Thallus very large 



D. Upper surface ashy colored 17. G. yellea 



D. Upper surface brown or darker 18. G. Dillenii 



C. Thallus small to middle-sized 



D. Rhizoids black; spores 8-13X4.5-7/* 16. G. polyrrhiza 



D. Rhizoids usually lighter; spores 14-22 X 6-11 /* . . . 15. G. angulata 

 B. Thallus ashy to grayish or darker below 

 C. Upper surface smooth 



D. Margins bearing rhizoids 10. G.cylindrica 



D. Margins not bearing rhizoids 14. G. grisea 



C. Upper surface more or less wrinkled and furrowed or reticulated 

 D. Thallus reticulated above 



E. Thallus smooth below, light colored 



F. Blackish brown or rarely pruinose above; 



apothecia 0.6-1.5 mm. across 9. G. proboscidea 



F. Pale ashy to darker or olive-brown above; 



apothecia 1-4 mm. across 11. G. rugifera 



E. Thallus reticulated below, dark colored 12. G. erosa 



D. Thallus rough and furrowed above, slightly 



punctured 13. G. torrefacta 



A. Thallus without rhizoids below 



B. Thallus reticulated or pitted below 

 C. More or less pitted below 



D. Upper surface more or less pustulate and wrinkled . . 5. G. hyperborea 



D. Upper surface smooth 6. G.deusta 



C. Reticulated below » 8. G. Miihlenbergii 



B. Thallus smooth to minutely granulose below 

 C. Thallus always smooth above 



D. Thallus deeply lobed and somewhat imbricated . . . 7. G. polyphylla 



D. Thallus lobed but not deeply so 4. G. phaea 



C. Thallus more or less granulose or reticulated above 



D. Granulose to wrinkled or rarely reticulated toward the center 

 E. Thallus smooth to chinky-areolate above; spores 



12-18X4.5-7/1 1. G. anthracina 



E. Thallus much wrinkled above; spores 



11-19X6-10/1 3. G. arctica 



D. Reticulated over the whole upper surface 2. G.decussata 



1. Gyrophora anthracina (Wulf.) Koerb., Syst. Lich. 99. 1855. 



Lichen anthracinus Wulf., in Jacq., Coll. Bot. 2:84. 1788. Umbilicaria an- 

 thracina (Wulf.) Schaer. 



Thallus middle-sized, becoming irregular and sometimes deeply lobed, smooth 

 to chinky-areolate, blackish brown; lighter to dark brown, or sometimes black- 

 ish pruinose below, and becoming minutely granulose; apothecia middle-sized 

 to large, 1-2 mm. across, sessile to substipitate, round, the disk concave to flat, 

 black, the blackish exciple well developed, raised and becoming crenulate; hypo- 

 thecium brown; spores oblong-ellipsoid, rarely somewhat curved, 12-18X4.5-7/*. 



On rocks at high elevation, New Hampshire and Yellowstone National Park. 



2. Gyrophora decussata (Vill.) Zahlbr., Cat. Lich. Univ. 4:678. 1927. 

 Lichen decussatus Vill., Hist. PI. Douph. 3:964. pi. 55. 1789. G. reticulata 



(Schaer.) T. Fries. Umbilicaria anthracina var. reticulata (Schaer.) Tuck. 

 Thallus small to middle-sized, ashy to blackish brown, or becoming whitish 



