Books and Current Literature. 



69 



of a particular species within a given area may be hopefully 

 undertaken. Contributions such as these, in which, by a suita- 

 ble division of labor, both the facts of local distribution and 

 topographic, climatic, and soil conditions are determined in 

 detail for definite areas, afford valuable and necessary data 

 from which to draw conclusions that at present rest upon alto- 

 gether too limited knowledge. It is to be hoped that such co- 

 operative work may be greatly extended. 



Wicken Fen, described in Yapp's Sketches of Vegetation at 

 Home and Abroad, is the largest existing area of the once exten- 

 sive "Fenland" of England, which occupied about 1,300 square 

 miles around the Wash. The greater part is now under cultiva- 

 tion or much altered by drainage, and even Wicken is drained 

 to some extent and exhibits all the features of a drying-up 

 marsh. The vegetation of Wicken is typical marsh (Hochmoor) 

 with grass-like monocotyledons — Gramineae, Cyperaceae and 

 Juncaceae — mixed with some Dicotyledons; bog plants such as 

 Sphagnum, Eriophorum, and Ericaceae are absent. A narrow 

 reed-swamp with Phragmites communis as the dominant plant 

 fringes the artificial drains; where land-formation has progressed, 

 the general vegetation is mixed, Cladium mariscus, Molinia 

 coerulea, Phragmites, being some of the dominant plants. Special 

 attention has been given to the relation of species to soil moisture, 

 and in a list, illustrated by a useful diagram, the author arranges 

 the commoner marsh plants "with respect to degree of soil 

 moisture which would seem to be the optimum; " the groups are: 

 A. Aquatics (Chara, Myriophyllum, Nymphaea, etc.), B. Semi- 

 aquatics (Sagittaria, Butomus, etc.), C. Wet-marsh plants 

 (Phragmites, Cladium, Menyanthes, etc.), D. Intermediate forms 

 (Lastraea thelypteris, Iris pseudacorus, Ophioglossum vulqatum, 

 etc.), E. Dry-marsh plants {Molinia, Aira caespitosa, Spiraea 

 ulmaria, etc.), F. Aliens from the dry land (Urtica dioica, Ajuga 

 reptans, etc.). These plants tend to arrange themselves over 

 the slight elevations and hollows of the plain, yet there is 

 mingling, the "wet plants" frequently invading dry places, 

 although the "dry plants" seem less capable of invading wet 

 places. This is traced to the habit of growth of "wet plants." 

 The rhizomes of wet-marsh plants (e. g., Cladium) are near the 

 surface where water prevails, but may be found fifteen to twenty 



