2b. Leaf, X 15. 



2c. Upper cells, X 125- 



2d* Leaf apex, X 50. 



23. Peristome tooth in profile, X 100. 



2f. Part of peristome, showing three teeth; median as seen by transmitted light; right, 

 dorsal face; left, ventral face; X 75- 



NOTES ON USEFUL AND HARMFUL MOSSES 



T. C. Frye 



In general mosses are considered neither useful nor harmful, with the ex- 

 ception of Sphagnum, about whose usefulness we have heard much during the 

 recent war. The facts concerning the effects of mosses upon man and his acti- 

 vities should however be recorded. Possibly this could be most successfully 

 done in the form of short notes on observations and experience. In the hope 

 that others may be encouraged to send such information to The Beyclogist 

 the following is presented: 



Dicranoweisia cirrhata is one of the first mosses to appear on shingle roofs 

 in western Washington. North roofs are much more readily covered than 

 south ones, on account of the retention of the moisture. Soot and dust are held 

 and thus soon a sort of soil is accumulated. In shade, a new roof may be covered 

 with moss within 10 years. Washington shingles are made of cedar {Thuja), 

 which strongly resists fungi and bacteria; but the dampness held by the moss and 

 soil very greatly increases decomposition. The remedy is to creosote the roof 

 every few years. 



Ceratodon purpureus appears in the tufts of Dicranoweisia cirrhata on Wash- 

 ington roofs, but it does not take hold first on a new roof, so far as I know. 



Rhacomilrium canescens ericoides sometimes takes all the other mosses on 

 a north roof , and seems to find it one of its best habitats for the production of 

 capsules. This was observed on quite old roofs at Friday Harbor, Washington. 



Bryum argenieum was observed to be the chief moss on an old north shingle 

 roof near Aberdeen, Mississippi. The shingles were cypress. This causes one 

 to wonder whether the kind of wood of which the shingles are made has anything 

 to do with the species of moss which grows on the roof. 



Neckera Menziesii is used occasionally by Japanese market gardeners in 

 the vicinity of Seattle, Washington, as a packing for asparagus and lettuce, to 

 retain moisture. It is so far inferior to sphagnum for this purpose than it is 

 questionable whether this is not done through ignorance. 



Brachythecium albicans takes the grass in lawns in western W'ashington when 

 the dampness is excessive, usually through over-watering. Shade increases the 

 dampness and thus favors the moss. The remedy is to water less, or to scatter 

 lime, or both. 



University OF Washington, Seattle, Wash. 



