66. Roccella] 18. ROCCELLACEAE 125 



18. ROCCELLACEAE 



Thallus fruticose, erect, more or less branched, differentiated into a well- 

 developed cortex surrounding the algal layer and the central medulla, attached to 

 the substratum by a basal disk ; apothecia round to elongated, immersed or sessile. 



The algal host is Trentepohlia. 



A. Cortex of transversely extending hyphae 



B. Spores hyaline 66. Roccella 



B. Spores brown 67. Schizopelte 



A. Cortex of longitudinally extending hyphae 65. Dendrographa 



65. Dendrographa Darbish., Ber. Deutsch. Bot. Ges. 13:321. 



pi. 25, f. 1-4. 1895. 



Thallus fruticose, erect, dichotomously branched, the cortex indistinct, com- 

 posed of longitudinal cohering hyphae, the medullary region tow-like, soralia 

 present or absent, spherical to flattened; apothecia lateral, disk-shaped, the exciple 

 colored like the disk or darker, surrounded by a decorticate thalloid one; hypothe- 

 cium brownish black to black; paraphyses branched; asci clavate; spores 8, 

 hyaline, 3-septate. 



The algal host is Trentepohlia. 



A. On shrubs, thallus branched 1. D. leucophaea 



A. On rocks and soil, thallus much branched 2. D. minor 



1. Dendrographa leucophaea (Tuck.) Darbish., Ber. Deutsch. Bot. Ges. 13:321. 



1895. 



Roccella leucophaea Tuck., Proc. Am. Journ. Sci. II. 25:423. 1858. 



Thallus greenish gray to ashy or rarely brownish, dichotomously branched, 

 erect and spreading, becoming much elongated and decumbent, flattened and 

 rarely perforated with holes below, becoming narrower and often cylindrical above, 

 soralia present; apothecia middle-sized to larger, 0.6-2 mm. across, lateral, sessile, 

 more commonly on the basal, flattened portions of the thallus, the disk flat to 

 convex, whitish pruinose or rarely blackish, the exciple thin, whitish; spores finger- 

 shaped, 17-28 X 5-7 fi. . 



On shrubs, along the coast and coast islands of southern California. 



2. Dendrographa minor Darbish., Ber. Deutsch. Bot. Ges. 16:13. 1898. 

 Thallus small, greenish gray to ashy, sometimes blackish below, erect to de- 

 cumbent, dichotomously much-branched, the branches cylindrical throughout or 

 more or less flattened below, becoming much entangled, soralia sparingly present 

 or absent; apothecia middle-sized to large, 0.6-2.5 mm. across, lateral, mainly 

 toward the basal portions of the thallus, sessile, the disk concave to slightly con- 

 vex, whitish pruinose to blackish, the exciple thickish; spores finger-shaped, 19-28 

 X 5.5-7.5 (i. 



On rocks and soil, near the coast, central and southern California. 



66. Roccella Lam. & DC, Fl. Fr. III. 2:334. 1815. 



Thallus fruticose, erect, more or less thickly branched, the branches flat, smooth 

 or soraliate, more or less twisted, the cortex of transversely extending, cohering 

 hyphae, the medullary tissue of longitudinally extending hyphae; apothecia lateral, 

 sessile, the disk flat to convex, the exciple colored like the disk or lighter, sur- 

 rounded by a thin, sometimes disappearing, thalloid one; hypothecium dark brown; 

 hymenium hyaline or brownish above; paraphyses branched; asci clavate; spores 

 8, hyaline, oblong to oblong-fusiform or fusiform, 3-septate. 



The algal host is Trentepohlia, found in the outer medullary tissue and the 

 inner cortex. 



A. On shrubs 



B. Spores not more than 20 /x in length 2. R. phycopsis 



B. Spores more than 20 m in length 4. R. Montagnaei 



