169 
Xeropliytic Adaptations of Bryophytes. 
jiaccidum of moist sheltered situations, they are more distant and 
are neither spirally twisted nor appressed. In B. Doniannm, an 
allied plant, and usually quite as xerophilous, the spiral twisting is 
not very pronounced, the thickened cells of the border rendering 
such a process unnecessary. Tortilla ambigua seldom has this 
spiral twisting but it is often present in wall-side specimens. 
The spiral twisting of the peristome in Barbida and Tortula 
has also a similar use for the protection of the teeth in the 
sporophyte. 
(c) Curving or Curling of the Leaves in the Dry State is another 
method which is similar to spiral twisting, in fact the two processes 
are somewhat similar. It is found in Ulota crispa, Barbida 
cylindrica, B. sinuosa, Pleurocluete squarrosa, Weisia crispa, W. 
sterilis, Cynodontium Wahlenbergii, Dicranoweisia, Dicranum 
montanum, and especially in Trichostomum crispulum, T. rnutabile, 
T. flavovirens, T. nitidum and T. tortuosum, all of which have leaves 
which are circulate, or so strongly curved as to be spirally inrolled 
on themselves. 
(d) Slighter Variations on Drying, so that the leaves are less 
exposed, are present in many xeropliytic bryophytes which do not 
possess any of the above-mentioned methods to a pronounced degree. 
They are also found in many plants which are mesophytex, or at 
the most, can only be considered semi-xerophytes. These variations 
include such changes as the crisping of the leaves in Diphyscium 
foliosum, Anomodon viriculosus, Dicranum fuscescens, Encalypta 
streptocarpa, the crumpling (or leaves becoming flexuose) in 
Campylopus flexuosus, Barbula rubella, Dicranum fulvellum, and 
many pleurocarpous mosses and foliose liverworts, e.g., Lophozia 
Flcerkii. 
(to be continued). 
