Leptogium. 221 



2. Leptogium. 



Collema sect. Leptogium Ach., Lich. Univ. (1810) p. 654. Leptogium 

 Gray, Nat. Arrag. Brit. Plants (1821): Krempelh., Geschicht. II (1869) p. 90; 

 Fr., Syst. Orb. Yeg. (1825) p. 255; Flot, Collem. (Linnaea 1850) p. 150 (em.); 

 Nyl., Syn. Lich. (1858—60) p. 118 (pr. p.), tab. 4 fig. 10, 16, 17; Linds., Mem. 

 Sperm/ (1859) p. 277, tab. XV tig. 43— 45; Th. Fr., Lich. Arct, (1860) p. 282; 

 Schwend., Unters. Flechtenthall. II (1863) p. 153 (em.), Ill (1868) p. 183; 

 Tuck., Gen. Lich. (1872) p. 93 (pr. p.); Minks, Fl. 1873 p. 352; Stahl, Beitr. 

 Entw. Flecht. (1877) p. 29; Tack., Syn. North Am. (1882) p. 154 (pr. p.); 

 Hue, Addend. (1886) p. 16 (pr. p., excl. subg. Amphidio, cet). — Tub, Mem. 

 Lich. 1852 (p. 30, 46, 202), tab. 6 fig. 10—12 (15—20). 



TJialkis foliaceus aut rarius subfruticulosus (sect. Polychi- 

 dium Ach.), raro duplex et e duabus lamellis superpositis consi- 

 milibusque formatus (sect. Dip loth all us Wainio), undique strato 

 corticali obductus, rhizinis ex hyphis solitariis aut partim laxe 

 cohaerentibus, incrassatis constantibus raro instructus (sect. M al- 

 io tium Ach.). Stratum corticate grosse parenchymaticum, vulgo 

 e serie simplice cellularum formatum, cellulis leptodermaticis. 

 Stratum medullare homoeomericum, hyphis circ. 0,0 2 — 0,0 4 mil- 

 lim. crassis, leptodermaticis, gelatinam abundantem e vaginis go- 

 nidiorum formatam laxe percurrentibus, aut gonidiis mucilagine 

 destitutis laxe immixtis, aut totum pseudoparenchymaticum (sect. 

 P o 1 y c h i cl i u m Ach.). Gonidia cellulis caeruleo-vircscentibus glau- 

 cescentibusve, globosis ellipsoideisve, moniliformi-eoncatenatis, he- 

 terocystis hyalinis intercalaribus, vaginis mucilaginosis, crassis, 

 confluentibus aut plus minusve distinctis (nostocacea), aut in spe- 

 ciebus pluribus baud distincte mucilaginosa. Apothecia thallo in- 

 nata, dein mox emergentia adpressaque, disco dilatato. Excipu- 

 lum t hall odes, strato corticali grosse parenchymatico, et strato 

 medullari gonidia bene aut haud distincte mucilaginosa conti- 

 nente, et perithecio hypothecium interne obtegente grosse paren- 

 chymatico et bene evoluto aut evanescente instructum, aut rarius 

 gonidia solum in basi apothecii continens (sect. Polychidium 

 Ach.). Paraphyses arete cohaerentes, haud ramoso-connexae. 

 Sporae S:nae, ellipsoicleae aut oblongae aut lusiformes aut fusi- 

 formi-aciculares aut bacillares aut murales (sect. Mai lo tium Ach., 

 Diplothallus Wainio et Euleptogium Wainio) aut 3 — pluri- 

 septatae [sect. Leptogiopsis (Mull. Arg.)l aut 1-septatae (sect. 

 Polychidium Ach.) aut simpliees (sect. L em mop sis Wainio), 



