LECANORA.] 



LFCANO-I.KCIDF.EI. 



371 



Subgen. 7. EULECANOHA Nyl. Not. Sallsk. pro F. et Fl. 

 Fenn. Fiirh. n. s. v. (180()) p. 127. — Thallus crustaceous, granuloao 

 or leprose, very rarely radiate. Apothccia lecanorine or lecideoid ; 

 spores occasionally numerous, sinqjle or variously septate, rarely 

 brown ; hymcnial gelatine variously tinged with iodine. Sperrao- 

 gones with jointed or simple sterigmata and various sperraatia. 



The largest subgenus of Lecanora and in several respects confluent 

 with the preceding subgenera. According to the structure of the apo 

 thecia and spermngonesit is divided into different serticms, most of which 

 have been viewed as distinct genera by sporologists. 



A. Spores Snse (rarely 8-lOnoe), polari-bilocular, h 



rarely simple or 1-septare, colourless ; 

 hymenial gelatine, especially the thecae, 

 bluish with iodine. Spermogones with 

 jointed sterigmata and straiglit spermatia. 

 {EucahipJaca Fr. fil. Lich. .Scaiid. p. 172.) 



a. Apothecia brightly coloured. (CaVopis- 

 mella AVedd. Mem. Soc. Cherb. t. xix. p. 276.) 



27. L. citrina Ach. Lich. Univ. (1810) 

 p. 402 ; Xyl. Bull. Soc. Bot. Fr. t. xiii. p. 366. 

 — Thallus effuse, granuloso-leprose, rimoso-sub- 

 areolate, citrine (K + purplish). Apothecia 

 moderate, plane or somewhat convex, orange- 

 yellow (K + purple) ; the thalline margin thin, 

 entire, at length obliterated ; spores ellipsoid, 

 polari-bilocular, colourless, 0,010-15 mm. long, 0,005-8 mm. thick. 

 — Sm. Eng. Bot. ii. p. 192 ; Tayl. in Mack. Fl. Hib. ii, p. 138 ; 

 Cromb. Grevillea, xii. p. 61. — Placodium citrinum Leight. Lich. 

 Fl. p. 177, ed. 3, p. 163. P. muromm subsp. eitnmon Cromb. 

 Lich. Brit. p. 45 ; var. e. citrinum Mudd, Man. p. 132. Lichen 

 citrinus Eng. Bot. t. 1793 (three lower figs.). Verruca ria citrina 

 HofFm. Deutsch. Fl. ii. (1795) p. 198 pro parte. Lichen candelarius 

 Huds. Fl. Angl. p. 444 pro parte ; With. Arr. ed. 3, iv. p. 27 pro 

 parte. Lichenoides crustositm, orbiadis et sciitellis jlavis Dill. Muse. 

 136, t. 18. f. 18 B.—Brit. E.rs. : Leight. n. 86 ; Larb. Lich. Hb. 

 n. 86. 



Differs at once from L. (Placodium) muronon, of which it has fre- 

 quently been regarded as a variety, in not being radiate at the circum- 

 ference, while connecting states are never foimd. The thallus occasionally 

 spreads extensively, varying somewhat in thickness, at times subevane- 

 scent, and is often of a greenish-yellow colour when growing in shadv 

 places, and in old plants is partially more or less gi-eyish-citriue. The 

 apothecia when present (for the plant is often sterile) are generaUv 

 numerous, at first somewhat uuiate, becoming at length convex, with the 

 thalhne margin excluded. 



Hab. On the mortar of walls, rarely on rocks, very rarely on old 

 trunks of trees, chieflv about towns and villages, in maritime, lowland, 



2 b2 



Fig. 63. 

 Lecanom cerina Ach. 

 — a. A epore, X 

 3.50. h. Jointed 

 sterigmata and 

 spermatia, X .500. 



