A SURVEY OF THE LOWER TEES MARSHES I05 



of Standing water. Moreover, Pi/Iicaria, Thalicinim and 

 Helleborine fail to appear ; so, too, there is an evident weaken- 

 ing of many of tlie elements of the upper marsh such as 

 Parnassitis and Poteriiiin, the greater abundance of Carex 

 gracilis, C. Goodeiiowii, C. riparia, Iris pseudacorus, Oenanthe 

 fistulosa serving to remind us of the proximity of the Reed- 

 swamp. Whence we see that, at any period other than when 

 the Iris and Trollius are in full bloom, the hues of the flowers 

 are of a very subdued tone and contrast violently with the 

 Epilobium and Gera/iimn lining the lodes, and with the greater 

 abundance of brightly coloured fiowers in the marsh above. 



The difTerences between the vegetation here and that just 

 studied having been indicated, no list will be given now. 



The Western Half. 



As described previously, the water content of the soil is 

 limited in this area, and the associations represented may be 

 deemed to be two, despite the fact that no hard and fast 

 boundary line can be drawn between them. These are the 

 rejuvenating Salicetum and the Juncetum communis in which 

 the vegetation becomes sparser and dwarfer — circumstances 

 induced by two controlling factors, (i) the lack of moisture, 

 {2) the advent of a considerable quantity of the parasitic 

 Rhinanthus crista-galli which, exactly as in a meadow, robs 

 the plants of their nourishment and brings about their 

 dwarfing. 



The slow diminution in moisture is likewise signalled by 

 the intrusion of plants usually members of drier associations, 

 viz.. Primula veris, Raimnculus acris, Tnssilago farfara and 

 Briza media, all of which are fairly plentiful, but more 

 particularly the first-named ; this struggles in competition with 

 the yunci with a considerable measure of success, and all 

 advance right into the heart of the J^uncus glaucus colony 

 up to the limits of the wetter soil which effectually represses 

 them. 



The prevalent conditions, too, are demonstrated by the 

 gradual elimination of the Trollius and, what seems to be its 



