85. Racodium] 24. COENOGONIACEAE 141 



A. Apothecia sessile or subsessile; spores scarcely more 

 than 10 /i in length 



B. Algal host irregularly arranged; apothecia flesh-colored 

 to yellow or reddish brown 

 C. Apothecia reaching 0.8 mm. across, flesh-colored 



to yellow 3. C. interpositum 



C. Apothecia not more than 0.5 mm. across, 



flesh-colored to reddish or brownish 4. C. moniliforme 



B. Algal host commonly circularly arranged; apothecia 



pale yellowish to reddish 1. C. Linkii 



A. Apothecia shortly stipitate; spores reaching IS n in length ... 2. C.disjunctum 



1. Coenogonium Linkii Ehrh., in Nees, Hor. Phys. Berol. 120. pi. 27. 1820. 



C. Linkii var. Leprieurii Mont. 



Hyphae 2-2.5 fi wide, the walls rather thick, variously disposed and forming 

 a loose network over the greenish gray, circularly or irregularly spreading algal 

 host; apothecia minute to small, 0.25-0.6 mm. across, subsessile, the disk flat 

 to slightly convex, pale yellowish to reddish, the exciple whitish; asci cylindrico- 

 clavate; spores becoming 1 -septate, ellipsoid, 6-8 X 2-2.5 ll, usually obliquely uni- 

 seriate. 



On trees, Florida. 



2. Coenogonium disjunctum Nyl., Ann. Sci. Nat. Bot. IV. 16:91. 1861. 



Hyphae about 1.5-2 /jl wide, rather thick-walled, extending irregularly and 

 forming a loose network over the greenish gray, irregularly or circularly spreading 

 algal host; apothecia small, 0.3-0.6 mm. across, shortly stipitate, the exciple 

 whitish; asci cylindrico-clavate; spores ellipsoid, 1-septate, 10-15 X 2.5-3.5 fi, ob- 

 liquely uniseriate or irregular. 



On trees, Alabama. 



3. Coenogonium interpositum Nyl., Ann. Sci. Nat. Bot. IV. 16:91. 1861. 

 Hyphae 2-2.5 fx wide, rather thick-walled, extending irregularly and forming 



a loose network over the greenish gray, irregularly spreading algal host; apothecia 

 small, 0.3-0.8 mm. across, subsessile, the disk flesh-colored to yellow, the exciple 

 whitish; asci cylindrico-clavate; spores 1-septate, 7-10 X 2.5-3.5 /a, obliquely uni- 

 seriate or irregular. 



On trees, from West Virginia to Florida, and westward to Texas. 



4. Coenogonium moniliforme Tuck., Syn. N. A. Lich. 1:258. 1882. 



Hyphae 2-2.5 /x wide, variously disposed in a network over the moniliform 

 cells of the algal host, forming a finely arachnoid, subareolate, yellowish to greenish 

 gray or olive-green crust; apothecia minute to small, 0.2-0.4 mm. across, sessile, 

 the disk fiat to slightly convex, flesh-colored to reddish or brownish, the exciple 

 whitish; asci clavate; spores ellipsoid, 1-septate, 8-11X3-4/*, irregularly ar- 

 ranged. 



On trees, Florida. 



85. Racodium Pers., Tent. Disp. Meth. Fung. 76. 1797. 



Thallus of unbranched, dark-colored, septate hyphae, extending parallel in 

 longitudinal direction over the surface of the pale algal host, covering the latter 

 as a cylindrical sheath; apothecia unknown. 



The algal host is Cladophora, and the filaments which support the lichen ascend 

 from the rocks and wood on which it grows. 



1. Racodium rupestre Pers., Tent. Disp. Meth. Fung. 76. 1797. 



Hyphae extending roughly longitudinally and parallel, 4-6 side by side, as a 

 dark brown to blackish layer, forming a complete or nearly complete cylindrical 

 sheath; apothecia unknown. 



On shaded rocks, New Hampshire, Rhode Island, Pennsylvania, and North 

 Carolina. 



