312 Howe: Preliminary notes on the genus Usnea 



F. Lax, sleader, scurfy (maximum length 2 m.); fibrils 



rectangularly arranged; apotliecia wanting U. longissima 



2. Compressed. 



Pitted, lax, slender (average length 6o cm.) ; fibrils capil- 



laceous; apothecia rare U, cavernosa. 



3. Angular. 



Rigid, coarse (maximum length i m.); fibrils rectangularly 



arranged; apothecia rare or wanting U. angulata. 



Family: Usneei 



Genus : Usnea (Dill) Ach. 



Usnea barbata (L.) Fr. 



This typical form must always include a great variety of indi- 

 vidually * developed examples, though never includes slender 

 filamentous plants of a pendular length exceeding 25 cm. In all 

 save habit of growth and absence of apothecia (the latter a purely 

 artificial line), it has every characteristic of the following subspecies 

 florida ; and from undoubted sterile examples of the latter, no line 

 can be drawn, U. barbata is not uncommonly hirsute, and sore- 

 diate, when it is recognized as the variety hirta^ along with seem- 

 ingly sterile examples of the next. It is sometimes dichroic, when 

 it is termed the variety rubiginea^ though this condition is more 

 common of so-called sterile ^m^^.f Plate 21 accompanying this 

 paper illustrates a unique phase which I have been able exactly to 

 duplicate but twice^J; and shows a curiously naked intermediate 

 condition between barbata and ceratiita (though much nearer the 

 latter), which, if barbata is dispensed with, falls naturally under sterile 

 ceratina, with fruited plants of which it was in one case growing. 



The distribution of the typical form is coextensive with that of 

 florida^ which is suggestive, except that it is this generally infertile 

 form that is largely restricted to the drier situations throughout 

 New England, exclusive of the upper Canadian zone, where it is 

 certainly only rarely represented* Typical examples are restricted 

 to the Upper Austral zone, being apparently intermediary between 



ceratina of the 

 Transition zone. 



/' 



*Nylander, Syn. Meth. Lich, 267. 1858-60; '^erectus aut pendulus," and *'e 

 pluribus constat formis." 



f These plants in herbaria have always been .difficult of determination, as pressing 

 often makes what was an erect plant in situ^ appear pendulous. 



X From South Canterbury, Conn., Plymouth, N. H,, and St. Martinsville, La. 



