Botany 51 



Lathyrus palustris and Myricagale. Viola stagnim has not been seen for some 

 years, and ir has probably followed Seiiecio paliidosus, S. palustris, Sonchus 

 palustris and Cicuta virosa into the list of species now extinct. It is possible 

 that Typha minima grew quite recently at Wicken. Throughout the 

 County the fen lodes and their niarguis naturally still carry an abundant 

 selection of the old fen species, although few of these are rare. 



Somewhat different in character from these true relics of the fens, are a 

 few sites on the Gault or Chalk, where local conditions formerly led to the 

 growth of small fens or even of acidic bogs. These sites have now been 

 drained, but from Hinton, Teversham, and Sawston Moors, the following 

 have been recorded: Drosera rotundifolia, D. arigUca, D. intermedia, Pingui- 

 cula vulgaris, Malaxis paludosa, Scirpus caespitosus, Eriophorum angustifolium, 

 Carex dioica, Molinia ccerulea. Sphagnum cymhifolium and Splachnum ampul- 

 laceum. Triplow Holes is a site on the chalk where fen species still survive, 

 and where Cladium has a local dominance. 



III. The Silt Fens 



The silt which forms the fen soil in the northern part of the County 

 round Wisbech (see Fig. 29) has probably been cultivated, apart perhaps 

 from the Saxon period, ever since its deposition in Romano-British times.' 

 Though "natural" vegetation is absent from it, it would be of great 

 interest to work out the progress of invasion and establishment of 

 species in the area during the quite definite period since its origin in 

 brackish water. So far this has not been done. 



At Foulanchor, near Wisbech, an area of reclaimed salt marsh falling 

 within the County boundary brings a number of maritime species into 

 the County flora. The tidal influence which formerly extended far inland 

 up the fen rivers has no doubt been responsible for inland records of the 

 more tolerant maritime species, such as Scirpus maritiuuis at Littleport, 

 Sutton and Upware, and S. tahernaemontani at Littleport. 



THE LOWER GREENSAND AREA 



The outcrop of Lower Greensand in the County is not extensive. Some of 

 it supports much of the market gardening and orchard area near Cam- 

 bridge, and the fields show typical psammophilous weeds. Only at Gam- 

 lingay, in the extreme south-west, does heath develop on it, and even here 

 extensive tree-planting, feUing and pig-keeping have greatly altered the 

 natural vegetation. Of the former heath dominants Calluna vulgaris and 

 Deschampsiafiexuosa are still abundant. The following also occur: Teesdalia 

 nudicaulis, Galium saxatile, Ulex europaeus, Cytisus scoparius, Luzula multi- 



' See p. 92 below. 



4-3 



