292 NATURAL HISTORY OF THE FARM 



sedges, rather than of grasses. It is a place of abundant 

 flowers the whole season through, from the cowslips and 

 cresses of spring to the asters and gentians of autumn. 

 It is a place where crawfish sink their wells, unmolested by 

 the plow, piling little circular mounds of excavated earth 

 about the entrance ; a place where rabbits hide, and where 

 song-birds build their nests; a place where the meadow 

 mice and shrews spread a network of runways over the 

 ground: in short, a place where rich soil and abundant light 

 and moisture support a dense population, among which the 

 struggle for existence is keen. 



If a fence -row extend down from the field into the swale, 

 let us follow that, and see how the wild plants change with 

 increasing soil moisture. The grasses of the fence-row begin 

 to be crowded out by sedges as the water-level comes nearer 

 the surface of the soil. Dry-ground asters and goldenrods 

 and lobelias disappear, and wet ground species of the same 

 groups appear instead. Bracken fern is replaced by marsh- 

 fern and sensitive fern; hazel by willow. Under foot, the 

 soil is growing softer, blacker and more spongy. 



If the swale has been cleared of woody plants, still alders 

 and willows are prone to linger about the wetter places, and 

 black-berried elder, osier-dogwood and meadowsweet about 

 the edges. Cat-tails and bulrushes (fig. 16, p. 36) will fringe 

 any open wet spot, and tussock-sedges and clumps of juncus 

 will rise on mounds of gathered humus, like stumbling-blocks 

 before our feet, where diffused springs abound. 



No two swales are alike in the character of their plant 

 population. But all agree in their meadowlike appearance, 

 in being made up of patches of rather uniform character, 

 where uniform conditions prevail, and in having each of these 

 areas dominated by one or two species of plants, with a 

 number of lesser plants as ''fillers" in its midst, and a greater 

 variety of miscellaneous plants growing about its edges. 



