NATURAL HISTORY OF THE BANKS OF THE TAY. 
57 
the plants which can adapt themselves to salt are the more favoured 
competitors, though under other circumstances they are the weaker. 
In short, the presence of the maritime plants in the places where 
they grow, and their absence from others, is simply an illustration of 
the survival of the fittest. 
Of the plants whose range is co-extensive with a distinct salinity 
the following are good examples :— 
Sagina maritima. 
Lepigonum salinum. 
Glaux maritima. 
Plantago coronopus. 
Atriplex Babingtonii. 
Juncus Gerardi. 
Triglochin maritimum. 
Glyceria distans. 
And, as regards the lower Tay, Plantago marithna. 
Aster TripoUut?i has a rather more extensive range, and the 
following, though most abundant where the water is distinctly salt, 
yet extend to where there seems to be no salinity:— 
Scirpus Tabern^montani. 
,, maritimus. 
Glyceria maritima. 
Group 2—Plants whose range seems to be governed by tempera¬ 
ture.—This group includes two sub-groups— 
(a) Species absolutely confined to the district, viz. ; — 
Trifolium fragiferum. 
QEnanthe fistulosa. 
Allium Scorodoprasum. 
Carex vulpina. 
„ acuta. 
(b) Species not so restricted, but which are certainly more 
abundant in the district than elsewhere, viz. ; — 
Cerastium tetrandrum. 
Nasturtium sylvestre. 
Epilobium hirsutum. 
CEnanthe crocata. 
Veronica Anagallis. 
Epipactis latifolia. 
Allium vineale. 
It may be, of course, that there are other causes than temperature 
which influence the distribution of these plants, but, so far as we can 
see, temperature seems to be the chief factor. 
Group 3—Plants dependent upon the influence of the tides.'— 
In this group we can place with certainty one plant only, namely, 
