320 Howe : Preliminary notes on the genus Usnea 



Uichodca thrives. I have seen no specimens from Marthas Vine- 

 yard, but find it commonly, and well represented from Connecti- 

 cut. Its presence in the Transition zone needs careful establish- 



T ViavA Avamfnf^r? Qnprimpn.c; from Eristol and Monkton. Vt.. 



ment. 



Mts 



M 



Usnea trichodea Ach. 



We have now left to consider only the true, epapillate species, 

 distinct and easily recognizable. The present, though variable in 

 color, due to age, xsgreen^ and only in young plants does it appear 

 yellowish. In maturity it is often an even darker shade of green 

 than that of normal fiorida, U. trichodea Is throughout, a dis- . 

 tinctly slender and filamentous species, somewhat suggesting 

 cavernosa (with which it is not often confounded) in character of 

 fibrillation, though rarely attaining a pendular length of more than 

 25 cm. It often bears apothecia, especially near the coast (Cum- 

 berland and Hancock counties, Me., and Plymouth, Bristol, Barn- 

 stable, and Dukes counties, Mass.), and this helps to distinguish it 

 from the commonly infertile dasypoga and plicata, which problem 

 the difference of geographical distribution makes largely unnec- 

 essary. Though, as has been said, with the latter it is continually 

 confused. 



Usnea trichodea is found commonly in the cold cedar swamps 

 of the Austral zone, in fact it appears that its range is somewhat 

 coextensive in the former zone with the Canadian *' islands " of 

 Chamaecyparis tliyoides (L.) B.S.P., and in the latter with the 

 cold swamp *' islands" of Larix, Picea, and Abies. In these 

 swamps trichodea^ however, grows also on various accompanying 

 trees — Acer.iox example. The unique faunal region of Cape 

 Cod and Marthas Vineyard, where Canadian and Austral faunas 

 are bewilderingly associated, supports this species in abundance. 

 The upper Transition zone or perhaps rarely lower Canadian zone 

 seems to limit its range, except on the coast, where it extends 

 northward certainly as far as Nova Scotia. I have found no 

 specimens collected above 1400 feet. This species is undoubtedly 

 the most common of the filamentous forms. 



