50 Botany 



It has been demonstrated experimentally that a mixed sedge community- 

 can be altered, in ten years by annual cutting, to something that fairly 

 closely resembles litter. Conversely, cessation of cutting will cause the 

 disappearance of such species as Carex panicea from late stages of Cladio- 

 Molinietum. 



There are, in fact, any number of inter-grades between the communities 

 we now describe, and they lie upon a series of deflected successions 

 suffering cutting of different intensities ; when left uncut, they rapidly 

 form carr. 



The droves in the fen, which are cut twice or thrice a year, might be 

 considered to show successions stiU further deflected from the prisere. 

 Certainly, the main drove, which has been in existence for at least two 

 centuries, has a most characteristic flora, very rich in species. 



From time to time, areas of mature carr are cleared of bushes, and very 

 striking vegetational changes foUow. Imiumerable seedlings of a great 

 number of species rapidly estabhsh themselves, and among them are 

 shoots of Iris, Ruhus caesius, Dryopteris thelypteris and other relicts of the 

 previous shade phase. The very rich herbaceous vegetation, if undisturbed, 

 quickly reverts to carr. 



II. Other Remnants of Fen Vegetation 



Around the fen margms there stfll exist a few much-modified areas of 

 fen vegetation. After Wicken, the largest of these is Cliippenliam Fen, 

 which hes 4 to 5 mfles north of Newmarket, where the Breckland sands 

 come down to the fens. Over most of tliis fen, peat-cutting has left deep 

 trenches, now filled densely with Cladium mariscus. Associated with it, 

 but especially on the ridges, Molinia is abimdant, while the following 

 species are more or less frequent : Schoenus nigricans, juncus ohtusiflorus, 

 Angelica silvestris, Eupatorium cannabimnn, Lythnun salicaria, Urtica dioica 

 Valeriana officinalis, Serratula tinctoria, and Scrophularia nodosa. Phragmites 

 is abundant throughout, and there is close general resemblance to the 

 Cladio-Mohnietum at Wicken, though bush colonisation is much sparser. 

 Finally, Chippenham Fen is still the home of Pinguicula vulgaris, Aquilegia 

 vulgaris, Selinum carvifolium and Carex pulicaris. 



Other remnants of fen vegetation occur in the Cam Valley at Dernford 

 Fen, now rapidly drying up, at Quy Waters and Quy Fen. The peat is 

 generally very shallow, and the fen species persist precariously in ditches 

 and pools. 



The County flora also includes species such as Stratiotes abides, Teucriwn 

 scordium, Villarsia nymphaeoides hanging on in these sites: while at 

 Wicken still persist Liparis loeselii. Ranunculus lingua, Peucedanum palustre. 



