THE DETEKMIXATIOX OF LICHENS IX THE FIELD 9 



Th. o£ lirupriglit or iisccnding- strap-shaped 



bodies. Ap. parmelioid 12. 



3. Th. 3^ello\v, K+ purplish. Sp. polarilucular, 



colourless Teloschistes . 



Th, grey or dark (occasiouall}' reddish) K — 

 or + 3^ello\vish. Sp. simple, colourless or 

 brownish 4. 



4. Th. light-gre}^ (occ. reddish) with firm me- 



dullary axis of closely-packed fungal fila- 

 ments (hyplise) Usnea 



Th. light-grey to black with medulla of 



loosely-packed h3'pha3 5. 



5. Th. usu. shining chestnut-brown (sometimes 



darker) and with small spines Cetraria aculeata. 



Th. grey or blackish (chestnut-brown in 



Alec fori a lUreryens) and without spines . 0. 



6. Th. small, black, zb shining, beneath some- 



times paler and sometimes with a few^ 



rhizinse Parmelia pubescens. 



Th. larger, whitish to dull-black, beneath 



concolorous and without rhizinae Alectoria (y ) . 



7. Cylinders hollow and often ± tapering at the 



apices 8. 



Cylinders solid and little tapering at the 



apices 9. 



8. Cylinders expanded at the apex into a cup, 



or branched with the axils of branches 



+ perforated Cladonia (//). 



Cylinders white, simple or almost so, and 

 tapering upw^ards Cerania. 



9. Cylinders with man}^ small squamules or 



granules on them Stereocaulon {h). 



Cylinders without squamules or granules on 



them 10. 



10. Th. of small, dark, ± erect lobes. Ap. par- 



melioid. Alpine or subalpine Parmelia corniculata. 



Th. larger, whitish or greyish 11. 



11. Th. of greyish branches, zbsorediate. Algal 



cells TrentepohUa. Ap. lateral. Maritime 



only Roccella. 



Th. of whitish branches, not sorediate. Algal 



cells green. Ap. terminal Sphaerophorus. 



12. Th. truly fruticose («). Sp. colourless, 1- 



septate Ramalina, 



Th. not truly fruticose (points of attachment 



many, under surface different from upper). 13. 



13. Subfruticose. greyish or whitish above, white 



or blackish below. Sp. colourless, sim})le . Evernia. 

 More or less spreading, paler below, villose 

 above or with cilia at margins. Sp. brown, 

 1-septate Physcia (1-3). 



