536 Watson. — Sphagna: Habitats , Adaptations , and Associates. 
acidic character, and when the catchment area for an urban water-supply is 
coincident, special means have to be adopted to prevent the so-called 
‘ humic acids ’ from attacking the lead pipes. Much research work has 
been done on this acidity of Sphagnum and a great deal of literature 
deals with it. 1 This acidic nature of Spliagna has a great effect on their 
habitats and distribution, and the main purpose of this article is to attempt 
to correlate their morphological with their ecological characters. 
The distribution in regard to altitude is more affected by human 
agency than through any discrimination by the species themselves. Many 
of our low-lying ‘mosses’ have been drained, the reclaimer has extended 
Fig. 1. Sketch-map of Somerset to show the distribution of Sphagna. 
The areas where Sphagna have been found are shaded; dotted lines represent the contour-line 
of 700 feet, the continuous lines indicate the contour-line of 1,000 feet. A few towns are indicated 
by crosses. 
the land available for agricultural purposes, and in England Sphagneta are 
seldom found below the altitude where it is economically possible for the 
farmer to bring the land into cultivation. This altitude varies according to 
many other influencing factors, but generally is about 700 feet Some of 
our lowland Sphagneta which still exist owe their survival to the excellent 
cover for game which is afforded by associated plants such as Betida , 
Myrica , and Molinia. The accompanying map of Somerset (Fig. 1) shows 
the altitudinal distribution of Sphagnum and illustrates how it is seldom 
1 See Skene: The Acidity of Sphagnum and its Relation to Chalk and Mineral Salts. 
Ann. of Bot., January, 1915. 
