386 LICHENACEI. [LECANORA. 



Often confounded with or regarded only as a variety of L. pyracea, to 

 which it is externally similar, though definitely separated by the dis- 

 tinctly-septate spores. It spreads extensively over the substratum, the 

 thallus "being frequently evanescent. The apothecia are very numerous, 

 and at times much crowded with a thalline margin rarely visible in their 

 earlier stage of growth. Though normally a corticolous plant, it at 

 times occurs on chalk, mortar, and limestone (very rarely in Britain), 

 when it is form mpestris (? Scop.) Nyl. Lich. Scand. p.' 145; Lecidea 

 ulmicola Tayl. in Mack. Fl. Hib. li. p. 129. 



Hob. On the trunks of trees, chiefly elms, rarely on rocks, from mari- 

 time to upland situations. Distr. General in most parts of England, 

 apparently rare in N. Wales, Scotland, and S. Ireland. B. M. : Great 

 Glenham and near Sotterly, Suffolk ; Hale P]nd, Epping Forest, Essex ; 

 Eynsford, Kent; Lewes and Glynde, Sussex; near Veutnor, Isle of 

 Wight; near Cirencester, Gloucestershire; near Mill Hill, Middlesex; 

 Elstree, Herts ; Windsor Great Park, Berkshire ; Stowe Park, Bucking- 

 ham ; Wimpole Park, Cambridgeshire ; Twycross, Leicestershire ; near 

 Worcester and at North Malvern, Worcestershire ; Island of Anglesea ; 

 near Masham, Yorkshire ; Leven's Bridge, Westmoreland ; Meldon Park, 

 Wansbeck Valley, Northumberland. Doune Castle, near Stirling ; 

 Pitfour, Aberdeenshire. Castle Connell, co. Limerick; Rostellan, co. 

 Cork ; Inisfallen, Killarney, co. Kerry. The saxicolous state has occurred 

 only in the following localities in S. and N. England and S. W. Ireland : 

 South Downs, Sussex ; Newton Abbot, S. Devon ; Ingleborough, York- 

 shire. Dunkerron, co. Kerry. 



48. L. phlogina Nyl. Mem. Soc. Cherb. v. (1857) p. 112; Lich. 

 Scand. p. 141. Thallus effuse, very thin, minutely granuloso- 

 leprose, citrine or yellowish-green ; granules globular, often some- 

 what scattered (K-f- purplish). Apothecia small, biatorine, plane or 

 at length convex, yellowish-orange : spores clliptico-oblong, polari- 

 bilocular, 0,011-15 mm. long, 0,006-9 mm. thick. Cromb. Journ. 

 Bot. 1871, p. 178; Leight. Lich. Fl. p. 223, ed. 3, p. 213. Par- 

 melia citrina var. phloyina, Ach. Meth. (1803) p. 180. Brit. Exs. : 

 Larb. Lich. Hb. n. 57. 



Sometimes viewed as merely a corticolous state of L. citrina, but allied 

 rather to L. pyracea, from which it is at once distinguished by the very 

 different thallus. The apothecia are generally rather scattered. 



Hab. On the trunks of old trees, ash and e]m, rarely on old posts from 

 maritime to upland districts. Distr. Found only in a few localities in 

 the Channel Islands and England. B. M. : St. Clement's Bay, Island of 

 Jersey. Near Ryde, Isle of Wight; near Hastings, Sussex; Penzance, 

 Cornwall ; Windsor Great Park, Berks ; Pampisford, Cambridgeshire ; 

 near Worcester ; Alston, Cumberland. 



Var. /3. lutea Nyl. Lich. Scand. (1861) p. 142. Thallus leproso- 

 pulverulent, whitish-citrine or pale-luteous. Apothecia pale-orange : 

 spores 0,011-12 mm. long, 0,006-7 mm. thick. Cromb. Grevillea, 

 xviii. p. 46. Lecidea eplxantha var. lutea Ach. Lich. Univ. (1810) 

 p. 209. 



A peculiar variety, differing in the more pulverulent, paler thallus, the 

 paler apothecia, smaller spores, and the nature of the habitat. The few 

 British specimens are well fertile. 



