126 



LICHEXACEI. 



[CLADONIA . 



c::^ 



'r^- 



(1 



Fig. 35. 



Cladonia pyxidata Fr. — a. Vertical section of 

 an apothecium, x30. b. Theca and para- 

 pLvsis, x350. c. Spores, xoOO. d. Vertical 

 section of a spermogonium. x30. e. Sterig- 

 mata, and/, spermatia, XoOO. 



32. CLADONIA HiU. 

 Hist. PI. (1751) p. 91 

 pro parte ; Hoffm. D. Fl. 

 ii. (1795) p. 114; KyI. 

 Xot. Sallsk. pro F. et Fl. 

 Fenn.Forh. n.s. v.(18G6) 

 p. 110. — Thallus laci- 

 uiato-foliaceous or squa- 

 moso-foliolose at the base ; 

 podetia branched or scy- 

 phiferous, more or less 

 pulveraceous or squa- 

 mose, entire or with the 

 axils and scyphi perfo- 

 rate. Apothecia termi- 

 nal, at first somewhat 

 plane and margined, but 

 immediately becoming 

 convex and immarginate : 



spores 8nae, oblong, simple, colourless. Spermogones usually situated 

 on the apices of the podetia, conical ; spermatia equally cylindrical, 

 somewhat curved or straight. 



The species of this genus are for the most part very variable. They 

 are consequently so connected by intermediate states and forms (the 

 result to a certain extent, perhaps, of hybridism) that it is sometimes 

 difficult to separate them. Unfortunately, also, the chemical thalline 

 reactions, apart from the characters of the basal thallus and the podetia, 

 are not of decided value here *. 



Sometimes there is seen a thin extended hypothalline-filamentose 

 patch, in which originate the basal squamules. The thallus is loosely 

 affixed by these filaments to the substratum, and in some instances, where 

 they decay, it becomes free. The spores and the spermatia of the dif- 

 ferent species do not varv much in size, the former being 0,008-0,015 mm. 

 long, 0,003-0,001 mm. thick, and the latter 0,008-0,012 mm. long, scarcely 

 0,001 mm. thick. The genus may, for convenience, be divided into the 

 following sections from the colour of the apothecia. Some plants of this 

 and the following genus, when growing in dry exposed places, become 

 more or less cervine or brownish, whence vars. spadicea, fuscescens, &c., 

 of authors. 



Oiu- islands are peculiarly rich in Cladonias ; further research will no 

 doubt bring additions to fight, as well as extend the distribution of some 

 already detected. 



* N viand er says : — " The genus Cladonia is not well adapted to show the 

 excellence of reactions, on account of the tinctorial particles being often but 

 sparingly present, by reason of the tenuity commonly of the cortex." — ' Flora,' 

 1886, p. 101. 



