_Systematic Account._

PELTIGERACEAE


Thallus foliose, with plectenchymatous cortex above (Fig. 5), or both
above and below (Fig. 2), with medulla of loosely interwoven hyphae,
trichomatic hyphae, usually present, attached to the substratum by
compound rhizoids; apothecia of considerable size, commonly on extended
lobes, usually imbedded in the tissues on the upper side, or more rarely
on the lower side; exciple inconspicuous; hypothecium usually light or
darker brown; hymenium usually pale below and brown or tinged brown
above; paraphyses simple or branched, distinct, seldom gelatinized or
coherent; spores hyaline or brown, 4- to several-celled, elongated.


KEY TO THE GENERA

1. Cortex developed on the upper side of thallus only,
spores hyaline Peltigera.

2. Cortex developed on both upper and lower sides of
thallus, spores brown Nephroma.




_Peltigera Willd. Fl. Berol. Prodr. 347. 1787._

Thallus foliose, usually adnate toward the center, with the lobes more