CHAPTER FOUR 



THE BOTANY OF CAMBRIDGESHIRE 

 By H. Godwin, m.a., ph.d. 



THEFOLLOWINGACCOUNT OF THE BOTANY OF CAMBRIDGE- 

 SHIRE is written primarily from the standpoint of the ecologist, 

 showing the vegetation of the area in relation to geology, topo- 

 graphy, and climate.' The chief vegetation types are considered in turn 

 according to the geological formations on which they occur. As this part 

 of England is particularly heavily cultivated, stress is specially laid on 

 those fragmentary communities still present in a fairly natural state, such 

 as the woodlands on Boulder Clay, the Chalk grassland, and the sedge or 

 scrub in the undrained parts of the Fenland. Since, moreover, no other 

 county contains so much of the old peat fens, the account deals at length 

 with what remains of fen vegetation upon their surface.^ Although a 

 portion of the Breckland, with its typical soil and vegetation, comes just 

 within the County boundary west of the River Kennett, it will not be 

 considered here as it has been dealt with separately by Dr Watt.3 



THE FENLAND 

 The English Fenland within historic times stretched over the greater part 

 of the area to the west and south of the Wash, extending as far north as 

 Lincoln and as far south as Huntingdon and Cambridge (see Fig. 47). On 

 the seaward side, the surface deposits are semi-marine sUt, laid dovm, and 

 afterwards occupied, during the Romano-British period.* On the land- 

 ward side, the upper layers are peat. This peat was produced by discharge 

 ofthefloodwaters ofthe Rivers Witham,Welland, Nene, and Ousernto the 

 extensive shallow basin ofthe fens. This water entering the fens has a high 

 mineral content, particularly that from the tributaries of the Ouse, which 

 drain the chalk escarpment to the east. The fen peats are therefore alkaline 

 in reaction, and support a vegetation of true "fen" type — the "Nieder- 

 moor" of German botanists. Such fens are dominated by grass-like 

 monocotyledons of the Gramineae, Cyperaceae, and Juncaceae, and, in 

 their drier stages, by shrubs and trees such as willow, alder, and birch. 



' I am indebted to the Editor of the Victoria County History (Mr L. F. Salznian) 

 for permission to use material prepared for a more extensive account of the vegeta- 

 tion of the County. 



* See also p. 17 above for a summary of the vegetational history revealed by 

 investigation of the successive layers of peat deposit in the Fenland. 



3 See p. 221 below. '' See p. 20 above, and p. 92 below. 



