No. II.] THE BRYOPHVTES OF CONNECTICUT. 33 



In the latter and by far the larger group should be placed 

 such species as — 



Metzgeria conjitgata Lencohryuui glancnm 



Plagiochila asplenioides Stereodon curvifolius 

 Bazsania trilobata Thamnium alleghaniense 



Yet, however much the preceding factors affect the distribu- 

 tion of the Mosses and Hepatics, the problem is eventually 

 reduced to another factor, viz., the amount, nature and cout 

 tinuity of the water supply. Many species grow only on dry, 

 exposed rocks, while to others the presence of free surface- 

 water is essential. Some of the latter grow only in standing 

 or slowly moving water, others are always found in rapidly 

 flowing streams. But the majority of the Bryophytes thrive 

 in an environment where they are not subjected to prolonged 

 periods of drought or inundation. 



Taking the requirements with regard to water as a basis, 

 Warming* recognizes four groups of plants : 



I. Xerophytes : plants which grow on rocks, or on soil 

 which contains, at least during the greater part of the year, a 

 very small amount of water. 



II. Mesophytes: plants adapted to soil containing a 

 moderate amount of water. 



III. Hydrophytes : plants which are completely or partly 

 submerged, or which grow in very wet soil. 



IV. Halophytes: plants which are adapted to a saline 

 soil. 



Considerable attention has been given to the ecological 

 relationships of the higher plants, and several authors have 

 attempted to classify the Bryophytes with respect to their 

 habitats. Warnstorff, however, was the first to adapt 

 Warming's classification to the group. 



Among the Bryophytes there are no true halophytes. Fol- 

 lowing Warming's classification the other three groups are 



* Warming: Lehrbuch der okologischen PflaEzengeographie. Second German 

 edition, 1902, pp. 121, 122. 



t Warnstorf: Kryptogamenflora der Mark Brandenburg, i: 20-23, 1903. 



