ON THE MODE OF DISSEMINATION AND ON THE 
RETICULATIONS OF RAMALINA RETICULATA. 
GEORGE JAMES PEIRCE. 
SEVERAL years ago, Professor W. G. Farlow, of Harvard Uni- 
versity, suggested my examining the thallus of Ramalina reticulata 
Krplhbr., with a view to determining the origin and mode of 
growth of the holes which give to this plant its characteristic 
appearance and its name. He generously allowed me to use all 
the material which was in the herbarium, but for various reasons 
I failed to obtain any results. 
On coming here, I was surprised to find the white and blue 
oaks (Quercus alba L. and Q. Douglasii Hook. & Arn.) festooned 
with this lichen to such a degree that many even young and 
small trees are as hoary in appearance as old New England pines 
overgrown by Usnea barbata Fr.t_ The live oaks (Q. chrysolepis 
Liebm.) of this vicinity are seldom the resting place of other 
than fragments of nets torn by storm and wind from other trees 
and blown to them. As a rule, the evergreens, whatever the 
shape of their leaves, have fewer fragments or whole plants of 
Ramalina growing upon them than deciduous-leaved plants. It 
would be a long and useless task to determine the species of 
shrubs and small trees which, forming the thickets on-the borders 
of the creeks, and composing the ‘ chapparal”’ covering parts of 
the foothills, are draped more or less by large or small fragments 
of Ramalina which have been caught in winter by their leafless 
branches, or on which the younger nets have grown from the 
spore. The reasons why Ramalina reticulata is found hereabouts | 
on deciduous-leaved trees and shrubs almost exclusively eb 
obvious: namely, that there is less chance of fragments catching 
The accompanying figure shows a white oak overgrown by Ramalina sigan 
The photograph of which this is a reproduction was very generously taken venlepitsd 
one of my students, ia [JUNE 
1 
I 
: 
4 
: 
