ECONOMIC USES OF LICHENS — LLANO 387 



The fungal components of lichens reproduce sexually by means of 

 ascospores, or basidiospores, depending on the type of fungus-sym- 

 biont present. When these spores germinate, however, growth cannot 

 continue unless the resulting hyphae come in contact w^th the algal 

 associate in the lichen species. A commoner method of propagation, 

 and perhaps the more successful, is asexual. This may be merely by 

 broken pieces of the thallus body being blown or carried elsewhere, or 

 by detachment of a minute mass of hyphae enclosing algal cells from 

 specialized structures known as soredia; this secondary method of 

 reproduction is not found in all species of lichens. Lichens have been 

 synthesized in a few cases by bringing together the two component 

 parts. 



Lichens are often mistaken for mosses, but the term "mosses" is 

 popularly used to include many unrelated plants. Certain species 

 of the lichen genus Cladonia are known as reindeer moss notwith- 

 standing the fact that they lack stem and leaves so characteristic of 

 true mosses. Irish moss is an alga {Ghondrus cripu.s) of shallow 

 coastal waters. The Spanish moss of the interior wooded valleys of 

 California is a lichen, Ramalina reticulata. The same name is more 

 commonly associated in the southern States with an epiphytic plant 

 growing on trees, wires, and roofs of houses. It possesses leaves, 

 stem, true roots, and flowers. This flowering plant {Tillendsia 

 usneoides) is a member of the pineapple family. Characters of a very 

 general nature might be used to differentiate the various groups : 



A. Plants reproducing by flowers and seeds Phanerogams 



(Seed-bearing plants) 



AA. Plants lacking flowers and seeds, reproducing by spores Cryptogams 



(Non-seed-bearing plants) 



B. Plants with stem and leaves Tbue mosses 



BB. Plants without stem and leaves. 



C. Plants normally found immersed in water, commonly bright 

 green, brown, red, or yellow-green, either attached or free 



floating Aquatic algae 



CC. Plants normally not immersed in water, gray or bright 

 colored but rarely bright green unless moistened, found 

 on soil, rocks, wood, or bark Lichenes 



LICHENS AS FOOD FOR INVERTEBRATES 



Certain studies (19) concerning invertebrates known to feed partly 

 or wholly on lichens include the feeding habits of mites, caterpillars, 

 earwigs, black termites, snails, and slugs. Invertebrates apparently 

 feed on all but the most gelatinous lichens which have almost complete 

 immunity because of their slimy covering. Dry, hard lichens are 

 rarely attacked, although it has been noted that two species of snail 

 graze on the endolithic lichens Verrucaria and Protohlastenia, mainly 

 on the thalli and the apothecia. Excrement from these snails con- 



