CRYPTOGAMS 32S 
4, Do you find fungi most abundant on young and healthy trees, or 
on old, decrepit ones? Account for the difference. (141, 348, 378.) 
5. Do you ever find them growing on perfectly sound wood anywhere? 
6. Are they ever beneficial to a tree? (86.) 
7. Is it wise to leave old, unhealthy trees and decaying trunks in a 
timber lot? 
Iv. LICHENS 
MarTERIAL. — Specimens can be found almost everywhere, growing 
on rocks, walls, logs, stumps, and trees. Some of the more common kind 
are: Parmelia, recognizable by the shallow spore cups borne on the upper 
surface of the thallus; Cladonia, by the little stalked receptacles, like 
goblets, in which its spores are held; Physcia, by its bright orange color. 
Where practicable, it is well to have several different kinds for comparison. 
iceland moss (Cetraria islandica) can generally be obtained from the 
grocers, and is a good example of an intermediate form between foliaceous 
and fruticose lichens. 
If the specimens are very dry, they will be too brittle to handle conven- 
iently, and should be moistened by soaking a short time in water. This 
will render them quite flexible and also bring out the green color more 
clearly. 
379. Examination of a typical specimen. — The com- 
Fic. 469. — Foliaceous lichens: A, Xanthoria (Physcia) parietina; B, Parmelia 
conspersa; a, spore cups. 
tained, are those that grow on rocks and tree trunks in flat, 
spreading patches. Their margins are much dented and 
