330 
STRUCTURE AND LIFE HISTORIES 
FIG. 238. A lichen, Parmelia perlata (L.) Ach. i. Plant, slightly 
reduced in size; a, apothecia; b, lobe of thallus; c, soredial patches. The 
soredia are vegetative reproductive bodies composed of both algal and fun- 
gal elements, and therefore able to reproduce the lichen; the ascospores, 
