130 



PEZIZALES 



r. Sterigmata exobasidial 

 s. Sterigmata endobasidial 



(r) Lower surface of thallus with 



cyphellae 

 (s) Lower surface without cy- 

 phellae 

 n, Apothecia marginal or terminal; 

 thallus often more or less fruticose 

 (m) Disks upright from the beginning 

 (n) Disks on the under side of thallus 

 lobes, which later twist to bring 

 them upright 

 (y) Thallus with cortex on upper surface 



alone 

 m. Apothecia superficial; thallus without 

 cyphellae 

 (m) Exciple with algae 

 (n) Exciple without algae 

 n. Apothecia terminal; cyphellae pres- 

 ent 

 y. Asci many-spored 

 (2) Thallus fruticose, erect or hanging, often 

 long and hair-like; radial, rarely dorsi- 

 ventral in structure 

 (a) Spores 1-celled or lacking 

 X. Medulla traversed by solid strands of 



variable number and size 

 y. Medulla uniform, without strands 

 (x) Cortex formed of hyphae running 

 lengthwise; asci 4-8-spored; spores 

 hyaline to brownish 

 (y) Cortex pseudoparenchymic, hyphae 

 more or less perpendicular to the 

 long axis 

 m. Medulla of hyphae running length- 

 wise 

 (m) Medulla loose, not horny; apothe- 

 cia unknown 

 (n) Medulla firm, horny 

 r. Thallus low, podetium-like; apo- 

 thecia unknown 

 s. Thallus fruticose, elongate; apo- 

 thecia present 

 (r) Thallus dorsiventral, without 

 fibrous branches; medulla 

 and cortex not separable 

 (s) Thallus radial, usually with 

 fibrous branches; medulla 

 and cortex readily separable 

 Medulla of hyphae running in all 

 directions 

 (m) Thallus more or less hollow 

 r. Thallus swollen, tubular 

 s. Thallus not swollen and tubular 



n. 



Parmeliopsis 231 



Pseudoparmelia 236 

 Parmelia 233; 32 



Cetraria 236; 32 



Nephromopsis 238 



Physcidia 230 

 Megalopsora 230 



Heterodea 230 

 Candelaria 231 



Subfamily Usneae 



Letharia 240 



Alectoria 241 ; 32 



Thamnolia 246 



Siphula 247 



Everniopsis 240 

 Usnea 245; 32 



Dactylina 240 



