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OF A CAMBRIDGESHIRE WOODLAND. 369 
more mixed. In this case Epilobium spp. and Angelica sylvestris often become 
temporarily very abundant. 
This society passes imperceptibly into the other societies by increase or 
decrease of moisture. 
Vegetation of recently Coppiced dreas. 
Whatever the vegetation was previous to cutting, great changes take place 
immediately afterwards owing to the sudden increase of light and of the evapora- 
tion rate. Plants from surrounding cornfields and pastures find admission in 
the sparsely populated soil thus exposed, but apart from these the vegetation 
becomes very mixed. When the shrubs are just at the end of their rotation 
the light is so much reduced that the ground flora is very scattered and does 
not form a continuous carpet. Accordingly, on cutting a suitable nidus is at 
once ready for species from all the surrounding areas. Grasses tend to become 
very numerous, the most prominent being: Deschampsia cæspitosa, Antho- 
vanthum odoratum, Bromus ramosus, Festuca gigantea, Brachypodium sylvati- 
cum, Poa nemoralis, Poa trivialis, Agrostis vulgaris, and Dactylis glomerata. 
Rubus собиѕ апа Rosa arvensis likewise spread very quickly from surrounding 
societies, the former especially often nearly choking out the exising vegeta- 
tion. Apart from plants of the ordinary societies, the following plants occur 
which were not noted in other parts of the wood :— Hypericum perforatum, 
Epilobium tetragonum, Carduus crispus, Dipsacus sylvestris, Myosotis umbrosa, 
and Leontodon hispidus. The following species also are much more abundant 
here than anywhere else in the wood: Centaurium umbellatum, Epilobium 
hirsutum, Carex muricata. 
Aquatic and Subaquatic Vegetation. 
In the calcareous clay area are several small hollows and ditches which are 
filled with water either the whole or part of the year. These hollows are to 
be distinguished from those described, which rarely if ever have free water 
in them. 
Some of these hollows lose their free water in summer except ш wet 
weather, but preserve a saturated soil; other examples remain all through 
the year as small ponds of 6 in. to 2 ft. depth. 
The former will be considered first. АП the examples of this type in 
the wood happened to be in an area recently coppiced at the time of 
these investigations, so that no data are available as 10 the effect of deep 
shading in these localities. Round the hollow in nearly all cases is a 
zone of Spirea Ulmaria and Deschampsia cwspitosa with Epilobium spp., 
E. hirsutum, E. tetragonum, and E. parviflorum with Rubus «тиз. The 
flora growing on the ooze-like mud varies in different cases. Those which 
dry up more quickly have such forms as the following :—Juncus glaucus, 
