GROUP: RADIATI-STRATOSAE Hue%*. 
Thallus composed of erect radially symmetrical podetia on a dorsi- 
ventral primary thallus; attached to subtratum without rhizoids. Gonidia 
homoeomerous. 
FAMILY: CLADONIACEAE Zahlbr. 
Thallus composite: Fruticose and foliose. Gonidia rotococcoid. 
Apothecia lecidiene. Spores simple to quadrilocular, hyaline. 
GENUS: STEREOCAULON Ach. 
Thallus composite, podetia solid, cortex cylindrical, ecorticate, rarely 
on a dorsiventral, primary thallus. Apothecia emarginate, disk dark. 
Spores fusiform or acircular, plurilocular, hyaline. 
Primary thallus present 
Spores 4, wide, ends blunt; podetia fre- 
quently ending in soredia . pileatum 
Spores 2.74 wide, ends pointed; podetia 
never ending in soredia : ; condensatum 
Primary thallus absent 
Squamules palmate-digitate 
Podetia glabrous or faintly tomentose, 
cephalodia with Stigonema 
Podetia loosely branched and spread- 
ing . : : : paschale 
Podetia in sents: erenions conglomeratum 
Podetia more or less densely aginentees. 
cephalodia with Nostoc 
Podetia repeatedly branched : : tomentosum 
Squamules of some other type 
Squamules coralline ; coralloides 
Squamules umbilicate or ena hie 
ular 
Podetia glabrous, cephalodia with 
Stigonema. . ee denudatum 
Podetia tomentose, eephalodia an 
Nostoc . ; : ; : E alpinum 
s 
* Note: Through the kindness and with the permission of Dr. L. W. 
Riddle Iam embodying his keys and distributional charts for the genera 
of this Group. Dr. Riddle has kindly brought them up to date since their 
original publication in the Botanical Gazette (50 : 285-304. 1910) and 
Rhodora (11 : 212-219. 1909). 
39 
