6 R. H. Howe: MANvuAL OF THE GENUS USNEA 
DESCRIPTION — typical: TZhallus pendulous, coarse, pliant, 
terete (rarely angularly deformed), cortex at Jength proximally 
scabrous, annularly scarred, stramineous to virescent ; primary 
branches coarse, at length intricately plicate, subpatent (max. length 
130 cm.); secondary branches much divided, subdichotomous ; 
fiorils polymorphous, tortuous, sparse or wanting, simple or com- 
monly subdichotomous. <Afothecia not uncommon, lateral and 
sessile, or subterminal, ample (1 cm.), now lacerate, disk flesh- 
colored or buff, periphery naked or ciliate. Spores as in U. forida. 
CONTINGENT PHASES: (a) Asin U. florida. 
(2) Branches sorediate (Usnea ceratina, 3} scabrosa Ach. Lich. 
Univ. 620. 1810). 
(c) Dichroic (red). This condition is rare, and never so far as 
observed affecting all parts of a plant (Usnea ceratina, var. 2 sca- 
brosa, form ferruginascens Crombie, Trans. Essex Field Club 4: 
60. 1885). 
(2) Naked of fibrils, the latter rarely present as a minute his- 
pid clothing (PLATE 3, FIGURE 2). 
SuBSTRATA : Deciduous and coniferous trees, occasionally on 
dead wood. 
GEOGRAPHICAL DISTRIBUTION: Common in the Austral and 
Transition zones, occurring also in a reduced, sterile, but perfectly 
characteristic state in the Boreal zone, reaching its most dwarf con- 
dition in Alaska (and Siberia).* It is best exhibited on the Pacific 
coast (Marin and San Mateo counties, California), where the plants 
are stramineous, and very pendulous (130 cm.), reaching possibly 
its highest development in Alpine Creek Cafion (1000 ft.), San 
Mateo Co., California, in the species (?) Usnea californica Herre, 
and in Mexico. Atlanticand Gulf coast specimens are less pendu- 
lous (30 cm.), generally virescent, and occasionally destitute of 
fibrils (see Bull. Torrey Club 36: f/. 27). 
OBSERVATIONS : I have included under this species all forms 
heretofore separated under ceratina. The slight variation of Usnea 
plicata that answers to Schaerer’s U. ceratina does not occur in 
North America so far as I have observed, nor is the form constant 
or desirable of recognition in the Old World according to the 
material I have examined, some of which was determined by 
Schaerer himself. 
* This is U. dardata, d plicata Fr. of Tuckerman and most modern authors. 
