2 26 HERRE 



Thallus pendulous, finally excessively elongated, terete, basally 

 slightly compressed, sparingly branched; thickly clothed with sim- 

 ple, nearly straight, horizontal, comparatively short fibrils. 



Apothecia small or very small, lateral or terminal; concolorous or 



pale tan; spores short ellipsoid, ^ _ /^. 



Color of thallus a soft but bright silvery or gray-green; herbarium 

 specimens fading badly, becoming finally a yellowish green. 



On trees above 1500 feet, in the redwood formation. 



About the head of Purissima Creek, altitude 1900 feet, the long 

 swaying silver-gray fronds of this lichen form a conspicuous feature 

 of the landscape. Here it attains a length of eight or nine feet, but 

 owing to its inaccessible situation only fragments are obtainable. 



Widely distributed over the cooler portions of the northern hemi- 

 sphere and on mountains in the tropics. Said to reach a length of 6 

 meters (Hungary, according to Zahlbruckner), or 10 meters (Java, 

 Nylander). 



9. USNEA CALIFORNICA Herre. 



Usnea californica Herre, Proc. Wash. Acad. Sci. 7: 345. 1906. 



Thallus large, stout, terete, much elongated and pendulous, 

 smooth; the coarse branches irregularly divided and wide-spread, 

 readily traceable nearly to the extremity of the plant; secondary 

 branches long and sub-divided; sparsely clothed with fibrils; branch- 

 lets and fibrils occasionally sorediate; color gray-green to yellowish 

 green. 



Fruiting specimens rare ; apothecia borne on secondary branches, 

 terminal or lateral, small to medium size; concolorous or tan; spores 



nearly circular to broadly elhpsoid,^ — — /^. 



On trees; as yet seen only about the head of Alpine Creek at an 

 altitude of 1000 feet, where it is locally quite abundant. A similar 

 plant, collected in Mexico, is in the Museum at Vienna. 



A robust, conspicuous plant, reaching a length ordinarily of 2-3 

 feet and probably the bulkiest of our Usneas. Quite different in 

 habit and general appearance from all our other species. 



