368 MH. В. S. ADAMSON: AN ECOLOGICAL STUDY 
Spiræa Ulmaria- Deschampsia ewspitosa Society. It may here be mentioned 
in reference to the low water-contents of this and the Mercurialis perennis 
Societies that they are almost confined to the southern end of the wood, 
where the slope of the ground, even though very gentle, causes a better 
drainage. 
This Fragaria vesca Society is essentially a mixed one, with its composition 
altering in different parts. In general the most abundant and important 
plants are :— 
Fragaria resed а. d Cirewa lutetiana 2...5... | 
Geum urbanum o.oo cece eee ls Nepeta hederacea ............ a 
Primula elatior о. a |  Jlypericum hirsutum | ..... ... da 
(or P. vulgaris) 
Other species in this society are :— 
Viola мана ...... Lue. es 0 Prunella vulgaris л... 00 
V. sylvestris... о... о Rumen viridis... sss. o 
Cardamine pratensis ......... vr Orchis mascula ............... m 
Spiræa Ulmaria ............ ... Ө Habenaria virescens a о 
Epilobium тотанит......... 0 Scilla nonseripta........... .... dla 
Sanicula europea ............ 0 Paris quadrifolia ,........... 0 
Cnicus palustris occ... T Arum maculatum / ............ o 
Centaurtum umbellatum ...... o Carew sylvatica ooo о 
Veronica Chamedrys ......... о Poa trivialis ......... enne lo 
Bartsia Odontites | .........L. lo Ап орган ит odoratum ... о 
Ajuga replans ooon la 
Digitalis purpurea vr occurs in one part of this society in small quantity. 
This plant has usually been regarded as absent altogether from the county of 
Cambridgeshire * t ł}. It is not mentioned at all in the county flora * or 
іп Watson's Topographical Botany for the County. It was recently 
discovered by Dr. Moss and myself, both in this wood and in White Wood, a 
few miles distant, situated on the Lower Greensand. Both this species and 
Epilobium angustifolium are Greensand plants, and this seems the limit to 
their eastern range in this wood. 
Mercuralis perennis occurs locally as pure patches in this society, but these 
do not cover any extent of ground. Deschampsia cwspitosa is also present 
in small quantity. 
Where the shade is dense (ree lutetiana becomes the dominant form 
often mixed with a little Spiræa Ulmaria, or locally forming nearly pure 
sheets. After cutting, this species may persist singly for some time, but 
gradually the others, so to speak, force an entrance and the flora becomes 
* Babington, 1860, p. 317. T West, 1898. | Watson, 1883. 
