Botany 59 



The moss flora of the Chalk grassland is equally characteristic ; the follow- 

 ing representative list is given by Dr P. W. Richards : 



Camptothecium lutescens^ 

 Briichythecium purum 

 Hypuuin tnollusaiin 

 H. chrysophyllum 



Seligeria pauciflora 

 , J Phasatm atrvkoUe 



abundant Brachythecium glohosmi 



Fissidens decipiens 



Trichostomum flavo-vireiis Hypntim mpressifome 

 T. tortiwsum ' var. tectonm 



Cylindrothecium concitinum var. ektum 



Ditrichumflexicauk Pottia lanceohta 



Weisia crispa P- recta 



W. microstoma Tortula pusiJla 

 Encalypta vulgaris ' Tliuidium ahietimim 



II. Woodland 



There are many indications that, vi^here grazing allows, scrub will in- 

 vade the Chalk grassland, and that the incoming bushes and trees will 

 often form dense thickets. Hawthorn, blackthorn, dogwood, and Rhamnus 

 catharticus, are usually the commonest shrub species: the evergreen yew 

 and juniper occur but sparsely. 



There is Httle evidence about the natural woodland vegetation of the 

 Chalk. Though several beech woods exist, they are either plantations or 

 have been much altered by planting, and the beech regenerates feebly in 

 them. In the upper peats by the fen margin, however (e.g. Wicken), 

 quite high percentages of beech pollen are to be found, which suggests 

 that natural beech woods were recently growing nearby. 



The beech woods are small and the floor is often wind-swept, so that 

 the undergrowth is sparse. It commonly includes hi the shrub layer 

 Ligustrum viilgare, Ruhus frtiticostis, Ilex aquifolitim, Sambticiis nigra, and 

 sometimes Taxus haccata. In the herb layer, there are commonly Poa 

 nemoralis, Festuca rubra, Brachypodimn silvaticiim, Nepeta glechoma, Fragaria 

 vesca, Myosotis silvatica, Listera ovata: less common are Ccphalanthera 

 grandiflora. Orchis maculata and Monotropa hypopithys. 



