28 LICHENS OF THE STATE OF WASHINGTON 



A. Thallus lacking distinct upper and lower cortices 19. Collema 



A. Thallus with a distinct cortex on the upper surface only, or on both 



surfaces 20. Leptogium 



19. Collema Wigg. Primit. Fl.-Holsat. 89. 1780. 



Thallus foliose, thin; gelatinous when moist, brittle when dry; often 

 hyphae grow close together to form an upper pseudocortex, no true cortices. 

 Apothecia small, circular, immersed, adnate or sessile; proper margin 

 present, thalline margin often very prominent; hypothecium hyaline to 

 brown ; paraphyses unbranched, agglutinated ; asci 8-spored ; spores hyaline, 

 muriform. 



A. On soil or rock. 



B. Apothecia crowded, oblong-ellipsoid. 2. C.crispum 



B. Apothecia scattered, spores ellipsoid 3. C.jurvum 



A. On bark or old wood. 



C. Spores submuriform, quadrangular or ellipsoid 4. C.verruciforme 



C. Spores not submuriform, fusiform or acicular 1. C.nigrescens 



1. Collema nigrescens (Huds.) DC. Lam. et DC. Fl. France 3rd ed., 2 :384. 

 1805. Lichen nigrescens Huds. Fl. Anglica Ed. 2. 450. 1762. Synecho- 

 blastus nigrescens (Huds.) Trev. 



Thallus when dry olive-green or greenish black, same color when moist ; 

 lobes small, rounded, flattened, beset with pustules, often ridged, margins 

 entire, ascending, closely adhering to the substratum. Apothecia often 

 numerous, scattered over the upper surface, often crowded towards the 

 center of the thallus, 2.0-8.0 mm. in diameter, circular, sessile ; disk reddish 

 brown or pale pink, flat to convex ; thalline margin thin ; hypothecium pale 

 yellow ; spores hyaline, fusiform or acicular, sometimes slightly curved, 5-7- 

 septate 49.4-70.0 x 3.8-6.0 z^. 



On bark: San Juan Co. : San Juan Island, 1906, Fink 235 (W). Grays 

 Harbor Co. : Westport, 1908 Foster 665V2 (W). 



2. CoUema crispum (L.) Wigg. Prim. Fl. Holsat. 89. 1780. Lichen crispus 

 Linn., Fl. Suec. 2nd ed., 406. 1755. 



Thallus when moist, dark olive (R) or metal bronze (R), when dry dark 

 brown to black ; lobes small, round, rather irregular, margins raised, dentate- 

 granulate, often the central part covered by numerous apothecia. Apothecia 

 0.5-1.0 mm. in diameter, circular, adnate to subsessile; disk burnt sienna 

 (R), concave; thalline margin, granular crenulate; hypothecium brownish; 

 spores hyaline, oblong-ellipsoid, 3-septate, muriform when mature, 16.5-23.1 

 X 9.9-13.2 fl. 



On soil or rock : San Juan Co. : San Juan Island, Friday Harbor, 1928, 

 1993; Roche Harbor, 1928, 1876. 



3. Collema jurvum (Ach.) DC. in Lam. et DC. Fl. Fran. Ed. 3, 2: 385. 

 1805. Lichen furvus Ach. Lich. Suec. Prodro. 132. 1798. 



