70 R. II. Yapp. 
D. Intermediate Forms. 
10. — Lastrea Thelypteris, Iris Pseudacorus, Thalictrum fiavum, 
Lathyrus palustris, Lythnun Salicaria, Oenanthe Lachen- 
alii, Hydrocotyle vulgaris, Lysimachia vulgaris, Mentha 
aquatica, Galium palustre, &c. 
11. —Ophioglossum vulgatum, Calamagrostis epigejos, Agrostis 
canina, Potentilla sylvestris, Angelica sylvestris, Val¬ 
eriana dioica, V. officinalis, Scabiosa Succisa, Carduus 
pratensis, &c. 
E. Dry-Marsh Plants. 
12. —Molinia coerulea, Aira caespitosa, Peucedanum palustre, 
Convolvulus sepiumd 
13 —Spiraea Ulmaria, Symphytum officinale, Eupatorium canna- 
binum. 
F. Aliens from the Dry Land. 
14.— Arrhenatherum elatius, Urtica dioica, Ajuga reptans, 
Galium Aparine, Centaurea nigra, Carduus arvensis 
and many others. 
The plants included in the above list are a heterogeneous 
assemblage of forms, of very varied habits, which grow under a 
variety of conditions. Broadly speaking, the majority of the semi- 
aquatic and wet-marsh plants are Monocotyledones, whilst the 
Dicotyledones become increasingly important towards the dry end 
of the series. Some of the latter are by no means confined to even 
dry marshes, but are commonly found by river banks, or in moist 
pastures, or in hedgerows bordering on damp ditches. Such are 
Spiraea Ulmaria, &c. But all the plants, except the aliens, are 
species usually found on soils with a moisture content above the 
average. 
The ground surface of Wicken Fen, although fairly flat in a 
general way, has many slight inequalities. In some parts there are 
gentle parallel undulations, which possibly mark the positions of 
former peat diggings, and there are many smaller elevations and 
depressions. Moreover, in excavating the Fen lodes, the dug-out 
peat was deposited so as to form banks raised a foot or two above 
the general level (see Text-fig. 11). 
Though no artificial pumping is resorted to, the surplus water 
soon drains off, by means of the lodes, into the River Cam ; with 
1 and 2 It will be seen that Cladium and Convolvulus are assigned 
to different places in this list to those in which they were 
placed by Wallis (/.c., p. 220). It is true that Cladium is 
often found in places where the surface soil is firm and fairly 
dry, while Convolvulus is found binding the stems of Phras'- 
mites together. But the roots of the former are found in 
very wet soil, or even in water, while those of the latter grow 
in drier soil. 
