DESTRUCTION OF MOSSES BY LICHENS 
CONTRIBUTIONS FROM THE HULL BOTANICAL LABORATORY 287 
FRANK P. MaWroade x 
(WITH PLATE XII) 
The deep-rooted conception of lichens as typical examples of 
symbiosis has induced workers along ecological lines to overlook 
the occurrence in xérarch successions of early stages which are 
dominated by the parasitism of lichens on mosses. This preliminary 
paper is intended to describe certain cases of lichen parasitism, 
and to emphasize the accuracy of Frnx’s definition of lichens: 
“A lichen is a fungus which lives during all or part of its life in 
parasitic relation with an algal host, and also sustains a relation with 
an organic or inorganic substratum.” 
The writer’s attention was first called to this situation when 
trying to separate some Cladonia lichen material from a moss colony 
in which it was growing. The intimacy of the mixture suggested 
that the lichen might be to some extent parasitic on the moss. 
Such phenomena seem to have been noticed previously by Bon- 
NIER," who shows that spores of lichens are known to germinate 
on moss protonemas and eventually to attack and kill them. He 
Suggests the occurrence of such parasitism in nature on a large scale. 
Moss-lichen colonies were chosen for study, in which both ele- 
ments were intimately mixed, illustrating cases of dominance on the 
part of one or the other. It was often impossible to determine 
the exact species oreven genus of the mosses concerned, because of 
the poor condition of the vegetative body and lack of reproductive 
organs. Mosses hampered by invading lichens seldom produce 
spores. Representative lichen-moss mixtures consisting of species 
* Bonnier, Gaston, Germination des spores des Lichens sur les protonemas 
des Mousses et sur des Algues differents des gonidies du Lichen. Compt. Rend. 
Soc. Biol. Paris. 40:541-543. 1888. 
rmination des Lichens sur les protonemas des Mousses. Rev. Gen. 
99. 
, Ge 
Bot. 1: 165169. pl. 8. 18 
321] [Botanical Gazette, vol. 72 
