126 MORPHOLOGY 



V. STRUCTURES PECULIAR TO LICHENS 

 I. AERATION STRUCTURES 



A. Cyphellae and Pseudocyphellae 



The thallus of Stictaceae has been regarded by Nylander' and others as 

 one of the most highly organized, not only on account of the size attained 

 by the spreading lobes, but also because in that family are chiefly found 

 those very definite cup-like structures which were named "cyphellae" by 

 Achariusl They are small hollow depressions about | mm. or more in 

 width scattered irregularly over the under surface of the thallus. 



a. Historical. Cyphellae were first pointed out by the Swiss botanist, 

 Haller^. In his description of a lichen referable to Sticta fuliginosa he 

 describes certain white circular depressions " to be found among the short 

 brown hairs of the under surface." At a later date Schreber^ made these 

 "white excavated points" the leading character of his lichen genus Sticta. 



In urceolate or proper cyphellae, the base of the depression rests on the 

 medulla; the margin is formed from the ruptured cortex and projects slightly 

 inwards over the edge of the cup. Contrasted with these are the pseudo- 

 cyphellae, somewhat roundish openings of a simpler structure which replace 

 the others in many of the species. They have no definite margin ; the inter- 

 nal hyphae have forced their way to the exterior and form a protruding 

 tuft slightly above the surface. Meyer" reckoned them all among soredia; 

 but he distinguished between those in which the medullary hyphae became 

 conglutinated to form a margin (true cyphellae) and those in which there 

 was a granular outburst of filaments (pseudocyphellae). He also included 

 a third type, represented in Lobaria pulmonaria on the under surface of 

 which there are numerous non-corticate, angular patches where the pith is 

 laid bare (Fig. 72). Delise^ writing about the same time on the Sticteae, 

 gives due attention to their occurrence, classifying the various species of 

 Sticta as cyphellate or non-cyphellate. 



Acharius had limited the name " cyphella " to the hollow urceolate bodies 

 that had a well-defined margin. Nylander' at first included under that 

 term both types of structure, but later^ he classified the pulverulent " soredia- 

 like " forms in another group, the pseudocyphellae. As a rule they bear no 

 relation to soredia, and algae are rarely associated with the protruding 

 filaments. Schwendener'', and later Wainio'", in describing Sticta aurata from 

 Brazil, state, as exceptional, that the citrine-yellow pseudocyphellae of that 

 species are sparingly sorediate. 



1 Nylander 1858, p. 63. "^ Acharius 1810, p. 12. 3 Haller 1768, p. 85. 



■> Schreber 1791, p. 768. ^ Meyer 1825, p. 148. « Delise 1822. ' Nylander 1858, p. 14. 

 " Nylander 1860, p. 333. ^ Schwendeiier 1863, p. 169. " Wainio 1890, i. p. 183. 



