215 



Cetraria islandica Ach., Meth. Lich., 293. 1803. 



Type: In the Linnean herbarium, Burlington House, London, 

 England. 



Type locality : " Eu ropae . " 



Original description: "foliaceous adscendens laciniatus; 

 marginibus elevatis ciliatis." 1. c. 



Diagnosis: Thallus fruticose, bifacial, brown, bicolored, 

 maculo-soraMate margins spinulose. Apothecial margins 

 entire. 



Description: typical: Thallus fruticose or subfoliose (max. 

 alt. 14 cm.), rigid, pale chestnut to dark brown, pale and 

 often sanguineous below; cortex nitidous, sublacunose, 

 maculo-soraliate ; branches bifacial, laciniate (max. width 

 8 mm.), canaliculate, subconnivent, margins cilio-spinu- 

 lose. Apothecia common, adnate, mostly subterminal, 

 ample (max. diam. i cm.), convex, margins entire or 

 crenulate, disk chestnut. Spores 6-11 X 3-5-5 m- 



Contingent phases: (a) Maculate throughout, with small 

 decorticate areas. (? C. islandica var. maculata Wain., 

 Arkiv for Bot. 8: 21. 1909.)* 



Fig. I. Range of Cetraria islandica (L.) Ach. 



(6) Laciniae slender above (C islandica var. gracilis see 



Cummings, Lich. Alaska 144. 1900). 

 (c) Spines long (4 mm.), rarely furcate (= C. islandica 



* Type loc, "prope Pitlekai." Orig. descpt. "Thallus laciniis angustis, margin- 

 ibus conniventibus, apicibus concavis aut anguste planiusculis, margine spinu- 

 losus, maculis decorticatis albidis impressis in latere inferiore instructus. Medulla 

 jodo caerulescens, CaCl202 non reagens. Haec variatio intermedia est inter var. 

 rigidam et crispam, in ambas transiens." 1. c. 



