A Somerset Heath and its Bryophytic Zonation. 83 
is very abundant and is associated with Calluna, Pteris and other 
plants characteristic of a dry heath association. 1 On the opposite 
side the wet heath merges into an Alnus thicket. 
Fig. 3. Diagrammatic section showing the different zones, except a 
“ pocket ” of Sphagnum cymbifolium (II C). The horizontal dotted line represents 
the general level of water under moist weather conditions. Scale 1 in 20. 
(II b on the right should be II B). 
A certain amount of shade is given to the herbaceous plants 
by the presence of Myrica gale and an occasional alder (Alnus 
glutinosa) or willow (Salix cinerea ), and for the smaller ones the 
rank-growing grasses and other vegetation provide not only shade 
but such severe competition that only a relatively small number of 
Juncue Molinia 
conglomerates caerulea 
Leontodon 
hi8piduB 
Luzula multiflora 
Molinia caerulea 
Nardu8 8tricta 
Erica tetralix 
Lotus uliginosue 
Anagallis tenella* 
Hypnum 
cupreBBif onne 
v. ericetorum 
Rhynchospora alba 
• 
Flngulcula luBitaniea , 
DrOBera angllca. 
Narthecium oesifragum 
Potamogeton 
polygonlfollus 
; BrachyVhecium purum 
Calypogeia trlchomanls 
'Brachytheclum purum 
Hypnum cuepidatum 
Sphagnum eubnltens' 
•Aneura multlflda 
■Fellia epiphylla 
"Aneura plnguls 
Fig. 4. Section through a water channel and a tussock. 
The section passes through a zone of Sphagnum subnitens. 
Scale 1 in 10. 
species occurs. This shading often gives a drawn-out appearance 
to the plants, and especially to the bryophytes which will be 
mentioned later. 
1 “ Types of British Vegetation,” p - 107. 
