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POPULAR HISTORY OE LICHENS. 



1. Usnea barb ata (barb a, a beard). Thallus greyish- 

 green or straw-coloured, frequently, in young state, erect, 

 rigid, and somewhat fruticulose, becoming with age flaccid 

 and pendulous ; dense cortical tissue of thallus consists of 

 roundish or polyhedral, thick-walled cells ; thecee small, ob- 

 oval ; spores minute, round, oblong or oval-oblong, double- 

 walled, pale yellow or colourless. — The following varieties of 

 this common species depend chiefly on the number, and mode 

 of ramification, of the cylindrical branches of the thallus. 



Yar. florida ; divaricate-ramose, rigid, erect, smooth, 

 fibrillose. A subvariety, hirta, is characterized by a verru- 

 cose or pulverulent condition of the filaments (E. B. 1354).^ 



Var. ceratina differs in being pendulous ; it may be smooth 

 or verrucose-pulverulent, fibrillose or not. 



Var. plicata ; pale straw-coloured, elongated, subdicho- 

 tomous, flaccid, and slender. 



Yar. dasypoga differs chiefly in the main branches being 

 covered with horizontally divergent fibrils. 



Yar. articulata is a prostrate or pendulous form, cha- 

 racterized by much stronger, broader branches, which are 

 divided into a series of turgid articulations, — frequently 



* The initials represent Sowerby's 'English Botany/ and the number 

 refers to the figure and relative description of the species. 



