THE LICHEN FLORA OF THE SANTA CRUZ PENINSULA 35 



Foliaceous Lichens. 



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

 (Cyanophycece.) 



B. Algae Scytonema XXX. Polychidium 



BB. Algae Nostoc. 



C. Thallus dark green without cortical layer XXXII. Collema 



CC. Thallus usually lead-colored, with distinct cortical layer. 



XXXIII. Leptogium 

 A A. Thallus not gelatinous when wet. 



D. Apothecia never present. 

 E. Thallus dark. 



F. Plant apparently black, the surface covered with black isidia. 



XXXIX. Sticta 

 FF. Plant dark brown, sub-fruticose; the ascendant, irregularly 



cut lobes with narrow white edge L. Cetraria 



EE. Thallus green or pale. 



G. Yellowish green with gray soredia; beneath villous or with 



naked pale spots XXXVIII. Lobaria 



GG. Plant more or less orbicular, often very large, grey, yellowish 

 or bright green; beneath black, usually brown-margined, 



more or less black-fibrillose XLIX. Parmelia 



DD. Apothecia usually present and abundant. 



H, Thallus attached at a single point near the center by an umbili- 

 cus. 



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

 /. Apothecia adnate, gy rose; thallus brown. . .XXV. Gyrophora 

 JJ. Apothecia immersed, appearing as minute dark specks on the 



ashy gray thallus II. Dermatocarpon 



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

 olive or blackish brown, expanded or ascendant. 



XXXIV. Heppia 



HH. . Thalius attached by numerous rhizoids, not umbilicate. 

 K. Apothecia adnate on undei side of marginal lobes. 



L. Algaae Nostoc; spores 2-4 locular XL. Nephroma 



LL. Algae Protococcus\ spores simple LI. Nephromopsis 



KK. Apothecia always on upper surface of thallus. 

 M. Thallus bright yellow or oiange. 

 N. Apothecia chestnut; spores simple, colorless. 



L. Cetraria 



NN. Apothecia yellow or orange. 

 O. Spores polai-bilocular, colorless, 8. 



LIX. Xanlhoria 



OO. Spores simple, 1 6 to 60 XL VEIL Candelaria 



MM. Thallus not bright yellow 01 orange. 



P. Thallus horizontal, orbicular or variously lobed; under 



surface with veins or cyphels. 



Q. Under surface with small white cyphels, villous or 

 fleecy XXXIX. Sticta 



