A Somerset Heath arid its Bryophytic Zonation. 93 
have any successional relation to the Molinia, in fact it is usually 
found on the outer and wetter side of the tussocks, but this is 
probably owing to the rank growth of the Molinia towards the 
inside, and is an exception to the general relation of these plants. 
(4) The fourth successive stage is indicated by the central 
portions of the Molinia tussocks where Ulex gallii, Potentilla erecta, 
Holcus lanatus, etc., are frequent invaders. Calluna has not yet 
succeeded in obtaining a footing in these areas. 
(5) An extension of the fourth successive phase, or what may 
be considered as a fifth, is shown at the drier edges of the wet heath 
(see Fig. 1) where drainage takes place in three directions, as a 
ditch runs by the side of the road. Many of the plants common to 
the district occur here, a number of Rubus spp. (Rev. W. Moyle 
Rogers paid a lot of attention to this district), and also a number of 
hedgerow plants, but tbe succession has been very much modified 
by human agency. A much more natural succession is probably 
shown in the adjoining dry heath, the vegetational character of 
which is indicated by the following list of plants. 
Polygala serpyllacea. 
Linum catharticum. 
Hypericum perforatum. 
„ humifusum. 
Ulex europaens. 
„ gallii. 
Vicia cracca. 
Potentilla erecta. 
Rubus fruticosus (agg.). 
Galium saxatile. 
Gnaphalium uliginosum. 
Senecio sylvaticus. 
„ jacobaea. 
Hypochoeris radicata. 
Leontodon hispidum. 
Teucrium scorodonia. 
Calluna vulgaris. 
Juncus squarrosus. 
Holcus lanatus. 
Anthoxanthum odoratum. 
Deschampsia caespitosa. 
Agrostis tenuis. 
Pteris aquilina. 
Lastrea aristata. 
„ spinulosa. 
Blechnum spicant. 
Hypnum cupressiforme 
var. ericetorum. 
Polytrichum juniperinum. 
Thuidium tamariscinum. 
Calypogeia trichomanis. 
Lepiota procera. 
Boletus edulis. 
The surrounding district has been largely reclaimed for pasture- 
land and the survival of the wet heath is probably due to the fact 
that the Molinia and Myrica offer excellent cover for pheasants, 
the “spoor” of which is very plentiful. The heath has some local 
notoriety as the home of adders and countless midges, and the habits 
of these animals do not lessen the difficulties of examining its flora. 
In conclusion I must tender my thanks to Mr. Tansley for his 
kind assistance in giving me valuable advice as to the methods of 
presenting the above account, and to Dr. Cavers for assistance in 
preparing the illustrations. 
