title: Collema nigrescens
text: # Collema nigrescens
  
  Collema nigrescens is a leafy (foliose) jelly lichen (Collema genus) found growing on the bark of trees such as bigleaf maples, in wetter coastal parts of $California.^{:34,36}$ It is commonly called button jelly lichen or bat's wing $lichen.^{:34,36}$ It is blackish-green when wet, and dark brownish-green to dark olive when $dry.^{:34,36}$ The photosynthetic partner is the Nostoc cyanobacterium that is spread throughout the thallus (main body $part).^{:34,36}$ Although foliose in form, like all jelly lichens, the thallus is not differentiated, lacking layers or an upper or lower cortex (lichen) and the cyanobacteria is spread throughout the $thallus.^{:34,36}$ It has dark purple-brown apothecia all $over.^{:34,36}$ It produces no reaction to lichen spot $tests.^{:34,36}$
  
  