328 Herre 



artificial key to genera of the foliaceous and 



fruticose lichens of the santa cruz 



peninsula, california. 



I. Foliaceous Lichens, 

 a. Thallus gelatinous when wet ; color always dark ; algae blue-green. 



b. Thallus without distinct cortical layer; generally dark green. 



XV. Collema^ 375. 

 bb. Thallus with distinct cortical layer ; usually lead-colored. 



XVI. Leptogiu?n^ 379' 

 aa. Thallus not gelatinous when moist. 



c. Apothecia never present. 

 d. Thallus dark. 



e. Plant black, with black granules; beneath pale, villous, 



with white cyphels X. Sticta^ 367. 



ee. Plant dark brown ; sub-fruticose ; the ascendant irregularly- 

 cut lobes with narrow white edges II. Cetraria^ SS^- 



dd. Thallus green or pale. 

 f. Plant yellowish green with gray soredia ; beneath villous, 



between naked pale spots X. Sticta^T^6^. 



ff. Plant more or less orbicular, at length very large ; gray, 

 yellowish or bright green ; beneath black, usually brown- 

 margined, more or less black fibrillose. 



VII. Par?nelia, 350. 

 cc. Apothecia usually present. 

 £. Thallus attached at a single point near the center by an um- 

 bilicus. 

 h. Apothecia visible to naked eye ; thallus large or of medium 

 size. 

 i. Apothecia adnate, gyrose ; thallus brown. 



IX. Gyrophora^ 3^5' 



ii. Apothecia immersed, appearing as minute dark specks 



on the ashy-gray thallus.. XXII. Dermatocarpofi^ 393. 



hh. Apothecia not visible to naked eye ; thallus very small, 



olive, with bluish edges XIII. Endocarpisciiin^ 374* 



gg. Thallus attached by numerous rhizoids, not umbilicate. 

 j. Apothecia adnate on under side of marginal lobes. 



XI. Nephroviium^ 370. 

 jj. Apothecia always on upper surface of thallus. 

 k. Thallus bright yellow or orange. 



/. Apothecia chestnut; spores simple, colorless. 



II. Cetraria^ 33^- 



