432 BOTANICAL GAZETTE [DECEMBER 
Other plants occurring amongst the grasses as subordinate members or 
visitors are: Fragaria virginica L., strawberry; Achillea mitlefolium L., 
yarrow; Leontodon autumnale L., fall dandelion; Brunella vulgaris 1 FE: 
Viola spp.; Cerastium spp.; Epilobium lineare Muhl., Rumex Britannica L.; 
Rhinanthus Cristagalli L.; Euphrasia officinalis L.; Aster Novti-Belgii L.; 
Lactuca leucophaea Gray; Solidago neglecta T. & G. Along the ditches 
grows Convolvulus sepinm L., and there are many others. 
The general adaptations of these forms to this habitat are 
sufficiently plain; they are typical mesophytic grasses, and the 
reclaimed marshes offer, as has already been traced, a typical 
habitat for them. But when we pass to details, the subject is 
not so clear. 
The two dominant members, the timothy and couch, occur 
variously intermingled, at times in about equal proportions and 
again with one or the other more abundant, even to such a degree 
that one may occur without the other for long stretches. No 
physical cause is traceable for these differences, beyond the fact 
that the timothy seems to have the advantage on the very best 
parts of the marsh, and the couch where salt is more abundant. 
Wherever they occur intermingled, patches of one or the other 
often exist without visible physical determinants; and their 
appearance gives the impression of a resultant of slight disturb- 
ances of equilibrium in the struggle between two evenly-matched 
forms (or else an adjustment between two mutually tolerant 
forms), here one and there the other, through the slightest causes, 
obtaining the advantage. Both plants seem to attain their 
greatest perfection and purity upon the banks of the aboideaued 
creeks, where no doubt the somewhat coarser soil, together with 
the better drainage, affords a better aeration for the roots, thus 
permitting the more luxuriant growth. At these and other 
places a marked phenomenon is to be ebserved, having no doubt 
an important bearing upon the nature of competition, namely, 
wherever these forms are most luxuriant, there the secondary 
and occasional forms are less abundant, and the latter come 
in with the decreasing vegetative vigor of the dominant forms. 
In the wetter, salter, and poorer marsh the Agrostis appears soi 
abundantly, thus forming the marginal member in that direction, 
as couch does in the other; but in addition it forms in places on 
