LICEA. 



[ 388 J 



LICHENS. 



BiBL. Works on Structural Botany ; 

 Schacht, Die Pjianzenzelle, p. 208, Berlin, 

 1852 ; Mohl, Vegetable Cell, and numerous 

 papers there referred to in the Botanische 

 Zeitung and Taylor's Scientific Memoirs. 



See also under Laticiferous Tissue. 



LICEA, Schrad. — A genus of Myxogastres 

 (Gasteromyeetous Fungi), growing on damp 

 rotten wood, in garden frames, &c., with 

 the peridia of elongate form, grouped toge- 

 ther, of only one layer, and containing few 

 or no filaments among the spores. Four 

 species are described as British, of which h. 

 fragiformis, Nees, is not uncommon on wet, 

 very rotten wood, moss, &c. ; the groups of 

 peridia just before maturity somewhat re- 

 sembling a strawberry; afterwards brownish. 



BiBL. Berk. Brit. Fl. ii. pt. 2. p. 321 ; 

 Ann. Nat. Hist. 2 ser. v. p. 367 ; Greville, 

 Sc. Crypt. Fl. pi. 308 ; Fries, Syst. My col. 

 iii, p. 195, Summa Veg. p. 458. 



LICHENS.— A class of Thallophytes or 

 cellular plants standing between the Algai 

 and the Fungi, exhibiting in the various 

 genera relations sometimes approaching 

 very closely to the one, sometimes to the 

 other of these two classes. Some authors 

 have thought fit to abolish the independent 

 existence of a class of Lichens, distributing 

 its members between the other two classes ; 

 while, on the other hand, Schleiden increased 

 the Lichens by adding to them all the theca- 

 sporous Fungi. De Bary has recently given 

 his adhesion to this on other grounds. 

 Here we shall consider the Lichens under 

 their ordinary limitation, as constituting a 

 class of Thallophytes distinguished from the 

 Algae in almost every case by the structure 

 of the thallus, the localization of the repro- 

 ductive function, and the aerial habit ; and 

 from the Fungi by the character of the thal- 

 lus, above all by the presence of globular 

 gonidia with green cell-contents, and in 

 most cases by the dry crustaceous habit, as 

 opposed to the fleshy consistence of the 

 majority of Fungi. 



The Lichens are almost universally either 

 dry encrusting bodies, growing upon bark 

 of trees, stones, earth, &c., as a pulverulent, 

 or rough and horny, or laminated and mostly 

 wrinkled and curled crust ; or as horny or 

 leathery, foliaceous or shrubby, ragged or 

 bristling patches, seldom rising much from 

 the surface which they overgrow ; of grey, 

 greyish-green, brown, yellowish, or even 

 reddish colour, and with a dead, pulveru- 

 lent and opake surface. The fructifications, 

 in which the spores are produced, are either 



little nodules (fig. 399), often with a minute 

 Fig. 399. 



Sphserophoron coralloides. 



Thallus with apothecia. 



Nat. size. 



pore at the summit, or raised lines (fig. 400), 

 or round, shield-shaped or cup-shaped bo- 



Fig. 401. 



Fig, 400. 



Fig. 400. Opegrapha atra. Thallus with lirellae. Nat. 

 size. 



Fig. 401. Borrera ciliaris. Thallus with apothecia. 

 Nat. size. 



Fig. 402. Section of thalamium. Magn. 150 diams. 



dies (fig. 401) scattered over the surface of 

 their fronds, or borne at the summits of the 

 branches of the shrubby kinds. In some 

 species the 'fruits' are the only parts visible 



