438 BOTANICAL GAZETTE [JUNE 
It is this variety that has been commonly distributed as Evernia prunastri 
in most of the North American exsiccati. 
EVERNIA DIVARICATA (L.) Ach. 
Tyre: Not indicated; the specimen on which Linnaeus based his species 
is in the Dillenian herbarium, Botanic Gardens, Oxford, England, and “is 
represented . . . . by only two or three sterile laciniae” according to 
Crompie. According to Wario, “Lichen divaricatus=Evernia divaricata 
Ach.,” as represented in the Linnaean herbarium. 
Type Locatity: “Helvetiae.” ~ 
ORIGINAL DESCRIPTION: “filamentosus pendulus angulatus articulatus 
intus tomentosus, ramis divaricatis, peltis orbiculatis sessilibus.” Linn. 
Syst. Nat. 713. 1767. 
Ficure: [Diit., Hist. Musc. pl. 12. f. 5. 1741]. Horra., Descript. et 
adnum. Lich. pl. 67. f. 1, 2, 3. 1801. 
Synonymy: Lichen divaricaius Linn. Syst. Nat. ibid.; Evernia divaricata 
Ach. Lich. Univ. 441. 1810. 
Diacnosts: Thallus pendulous, flaccid, compressed (subbifacial), glabrous, 
stramineous. 
DEscrIPTION: typical. Thallus pendulous, flaccid, subterete, » 
compressed or angulate; cortex glabrous rugose and annularly 
ruptured, exposing cottonous medulla, stramineous; primary 
branches divaricate, dichotomous, sometimes echinate (max. length 
35 cm.); secondary branches dichotomous, apices acuminate and 
darkening. Apothecia uncommon, lateral, small (max. diameter 
2-6 cm.), marginate, thalline exciple rugose, disk chestnut, margins 
finally crenulate. Spores 5-10X3.5-6 b. 
CONTINGENT PHASES: unobserved. 
SUBSTRATA: On coniferous trees. 
EOGRAPHICAL DISTRIBUTION: Occurs rarely in the Boreal zone. 
been reported from the following localities in the Rocky Mountains: Cali- 
fornia (Hall), Colorado (Brandegee), Bamft (Macoun), Mt. For-get-me-not, 
Elbow River (Macoun), British Columbia (Macoun). I have seen specimens 
from Divide Mt., 8000 ft., Montana (Williams), and Alpine, Colorado. The 
specimen in the U.S. Nat. Herbarium from Colorado, collected by Professor 
G. Vasey (referred to by TucKERMAN), is unquestionably Usnea cavernosa 
uck. I have seen no fertile specimens from our area. 
OBSERVATIONS: This plant is so rare in North American collections that 
its exact range is little known. It is undoubtedly a Boreal species, and may 
be looked for throughout the Rocky Mountains above 7000 ft. Its extreme 
flaccidity, and more or less compressed thallus, distinguishes it from Usned, 
It has 
