HASSE—LICHEN FLORA OF SOUTHERN CALIFORNIA. 71 
COLLEMACEAE. 
Thallus gelatinous, crustaceous-foliaceous, squamulose or minutely fruticulose, 
homodmerous, with blue green Nostoc alge; apothecia immersed in the thallus, 
close-fruited or open-fruited, or adnate-sessile, mostly lecanorine, rarely biatorine, 
with or without a proper parathecium and hypothecium (excipulum); disk puncti- 
form or expanded; asci 8-spored; spores colorless, globular or acicular, simple, 
bilocular to several-locular or muriform. 
In our species, apothecia lecanorine, spores bilocular to muriform. 
KEY TO GENERA. 
Thallus ecorticate........--.--------- 220s eee eee eee CoLLEMA (p. 71). 
Thallus corticate on one or both surfaces .......-.------ LEptToGium (p. 73). 
COLLEMA (Hiller) Weber. 
Thallus foliaceous, macrophylline to microphylline, sometimes almost crustaceous, 
gelatinous when moist; apothecia circular, innate to adnate-sessile, lecanorine; proper 
exciple present or wanting. 
KEY TO SPECIES. 
Lobes of thallus large, rugulose. 
Beset with granulations..........--------+-ee+eee seers 2. C. aggregatum. 
Not beset with granulations. 
Apothecia dull reddish, naked........-..---------- 1. C. nigrescens. 
Apothecia bluish pruinose...........--------++-+-- 3. C. glaucophthalmum. 
Lobes small. 
Growing on a mineral substratum. 
On rock. 
Lobes turgid.......-...--------2-+- eee eee eee 7. C. pulposum. 
Lobes not turgid..............------2+22e eee 6. C. cheileum. 
On earth. 
Lobes thin, appressed...-..........------------ 8. ©. limosuin. 
Lobes suberect, clavate..........-..-+++-++-+--- 5. C. coccophorum. 
Growing on bark. 
Lobes erect, fasciculate. 
Spores fusiform. ............--++-+----+-++0++- 4. C. fasciculare. 
Spores rounded-quadrangular........----------- 9. C. verruciforme. 
1. Collema nigrescens (Leers) Wain. 
Thallus foliaceous, black green, round-lobed, flattened, closely adherent, radiate- 
rugulose, lacunose beneath; apothecia sessile or elevated, 0.5 to 0.75 mm. in diameter; 
disk flat, red brown with a thin thalline margin, this finally obscured; epithecium 
subcontinuous, brown, thin; thecium colorless, 80 to 96 » high; paraphyses coherent, 
strict; hypothecium pallid amber yellow; asci clavate, nearly equaling the thecium 
in height; spores fusiform, 6 to 8-locular, 60 to 68 » long, 5 to6 » thick; hymenial gela- 
tine with iodine blue; spermatia short, straight, 4 to 7 » long, 1 to 1.5 » thick. 
On various barks in the Santa Monica Range and on slate rocks, on which substratum 
it is generally sterile. 
2. Collema aggregatum (Ach.) Nyl. 
Thallus black green, foliaceous, orbicular, 2 to 4 cm. in diameter, round-lobed, 
entire or with short marginal ciliw, the upper surface irregularly rugose and beset 
with granulations, closely adherent except toward the ascending margins, somewhat 
paler beneath, lacunose and fenestrate; apothecia elevated-sessile; disk flat, at first 
delicately pruinose, later naked, reddish to almost concolorous with the thallus, the 
