188 32. PELTIGERACEAE [ 118. Peltigera 



below, often lighter toward the margins, bearing few long rhizoids, but uniformly 

 covered with a dense nap; apothecia middle-sized to large, 3-7.5 mm. across, borne 

 on narrow, extended lobules, round and rolled backward, the disk reddish brown, 

 the exciple becoming crenulate; hypothecium dark brown; spores hyaline, 3-5- 

 septate, acicular, 50-72 X 4-6 ft. 



On soil and over mossy rocks, from New England westward to the Rocky 

 Mountains. 



8. Peltigera rufescens (Weis.) Humb., Flor. Frib. Specim. 2. 1793. 

 Lichen caninus, rufescens Weis., PL Crypt. Flor. Goett. 79. 1770. 



Thallus small to middle-sized, closely adnate, smooth to somewhat downy, 

 greenish gray to brown, the lobes crowded, narrow, with crenate, much-elevated 

 margins ; brownish to dark brown below, thickly reticulated with brown veins with 

 numerous brown rhizoids; apothecia middle-sized to large, 3.5-7.5 mm. across, 

 borne on narrow, extended lobules, rolled backward, the disk brown to blackish 

 brown, the exciple becoming crenulate or toothed; hypothecium brownish; spores 

 hyaline, 3-7-septate, acicular, sometimes curved, 40-68 X 3.5-5 /x. 



On soil, throughout northern United States, and southward west of the Missis- 

 sippi River. 



9. Peltigera praetextata (Sommerf.) Vainio, Term. Fuz. 22:306. 1899. 

 Peltidea nlorrhiza var. praetextata Sommerf., Suppl. Fl. Lapp. 123. 1826. 



P. rufescens var. praetextata (Sommerf.) Nyl. 



Thallus middle-sized to large, adnate toward the center, more or less covered 

 with coralloid branchlets, especially toward the margin, greenish gray to brown, 

 with broad, wavy lobes, ascending toward the irregular margins; whitish below, 

 bearing numerous whitish to brown veins and rhizoids; apothecia middle-sized, 

 2-5 mm. across, borne on narrow, extended lobules, rolled backward, the disk 

 brown to brownish black, the exciple usually denticulate; hypothecium brownish 

 to brown; spores hyaline, 3-5-septate, sometimes slightly curved, 42-56X3-5^. 



On soil, old logs, and over mosses, Ohio and Michigan. 



10. Peltigera canina (L.) Willd., FL Berol. Prod. 347. 1787. 

 Lichen caninus L., Sp. PL 1149. 1753. 



Thallus middle-sized to large, closely adnate, greenish gray to ashy and brown- 

 ish, with broad ascending lobes, and round to irregular or crenate margins, partly 

 covered with trichomatic hyphae; whitish below or rarely brownish toward the 

 center, bearing many whitish to darkening veins and rhizoids; apothecia middle- 

 sized to large, 4-8 mm. across, borne on extended, suberect lobules, round to 

 commonly rolled backward, the disk reddish to dark brown, the exciple sometimes 

 becoming crenulate or irregular; hypothecium brownish; spores hyaline, 5-7- 

 septate, acicular, sometimes curved, 38-72 X 3-5 fi. 



On soil and over mosses, throughout the United States. 

 f. spongiosa Tuck., Syn. N. A. Lich. 1:109. 1882. 



The veins of the lower side pale, the rhizoids whitish or darkening and running 

 together into a conspicuous spongy nap. 



On soil, rocks, or at the base of old trees, throughout the United States. 

 f. leucorrhiza Floerke; Flot, 28. Jahresber. Schesisch. Gesellsch. Kultur, 124. 

 1850. 



Peltidea leucorrhiza Floerke, in Hepp, Flecht.-Fl. von Wiirzburg, 54. 1824. 



Thallus very large, slightly thinner, the trichomatic hyphae very prominent; 

 whitish below, bearing conspicuous white veins and scattered rhizoids. 



On soil, Minnesota. 

 f . membranacea (Ach.) Duby, Bot. Gall. 2:598. 1830. 



Peltidea canina var. membranacea Ach., Lich. Univ. 518. 1810. 



Thallus thinner, smooth to minutely pitted; white below and reticulated with 

 whitish veins; apothecia smaller, borne on short lobules. 



On soil, logs, and mossy rocks, California and Oregon. 



