28 SCIENTIFIC SURVEY OF NORWICH AND DISTRICT 
flexilis, N. translucens, N. tenuissima, Tolypella prolifera, Chara canescens 
and C. connivens (30, 31). 
(3) Ranunculus lingua, in the forefront of the reed advance, is becoming 
scarcer. Typha latifolia, T. angustifolia and Sparganium spp. are often 
abundant, with odd clumps of Rumex hydrolapathum. Scirpus lacustris 
is, as Miss Pallis puts it, ‘ the most aquatic of the reed-swamp dominants ’ 
in the broads of the Bure and its tributaries, but almost absent from 
extensive swamps in the Yare valley (5). 
(4) The ‘ closed’ reed and reed-grass communities vary as to their 
dominant species in the separate river systems. In the Bure region 
Phragmites communis holds sway, while that of the Yare is to a great extent 
characterised by the presence of much Glyceria aquatica, in some places 
almost excluding Phragmites. Thalictrum flavum is common in the latter 
and almost completely absent from the former. The following are 
common to most well-established marshes of this kind, varying to some 
extent as the area is frequently or irregularly mown or burnt: Lychnis 
flos-cuculi, Lotus uliginosus, Vicia cracca, Spirea ulmaria, Lythrum 
salicaria, Epilobium hirsutum, Angelica sylvestris, Peucedanum palustre, 
Valeriana officinalis, Eupatorium cannabinum, Cirsium palustre, Lysimachia 
vulgaris, Iris pseudacorus, Cladium mariscus (locally), Carex riparia, 
C. acutiformis and C. paniculata, Phalaris arundinacea, occasionally 
Calamagrostis canescens, Poa trivialis, Festuca elatior and Equisetum 
palustre. Cicuta virosa thrives at the edge of many tussock-swamps. 
Lathyrus palustris is becoming rarer, requiring as it does conditions which 
are transient in marsh development. Cnanthe lachenalii is present, 
usually near the lower reaches of the rivers, where also Sium latifolium is 
not uncommon. Sonchus palustris is well established among reeds beside 
the Bure and Waveney, in two stations ; and Acorus calamus grows beside 
several of the broads. Butomus umbellatus is not uncommon in dykes, 
especially in the Yare Valley. 
(5) Thickets of alder or sallow and ash frequently encroach on the older 
reed-swamp, eventually dominating it; the margins of these ‘ carrs,’ as 
they are called, are often marked by trailing masses of Calystegia sepium 
and patches of Solanum dulcamara. Clumps of Carex paniculata line 
channels passing through them, and in some of the spaces Osmunda 
regalis grows, with Dryopteris thelypteris, Peucedanum palustre, and relics 
of the earlier marsh flora. The wilderness of fallen branches is compara- 
tively rich in mosses and lichens. Ribes nigrum, R. rubrum, Rhamnus 
catharticus, R. frangula, and Viburnum opulus, are typical shrubs in this 
community ; ash becomes abundant, with oak and hazel coming in at 
the climax. 
(6) In the ‘ growing-up’ process, certain pools and hollows in the 
marshes tend to become isolated and poorly drained, presently supporting 
the flora of a sub-acid fen(g) with Sphagnum, Viola palustris, much 
Hydrocotyle vulgaris, Eriophorum spp., Juncus subnodulosus and Schaenus 
nigricans, and may develop into wet heath (q.v.). The birch frequently 
encroaches on such areas. 
Fungi typical of the sallow-carrs are Trametes rubescens and Pholiota 
ertnacea, which are frequent on the dead boughs. The whole of the 
