294 NATURAL HISTORY OF THE FARM 



to find a place on some disturbance of existing condi- 

 tions. A niuskrat or a mole U])hcaves a mound of earth, 

 and the seeds of these annual weeds, fallinj^ into this 

 imoccna] icd soil, flourish there for a season ere the root- 

 stocks of more permanent perennials again invade it. The 

 annuals of the swale are quick-growing things, that depend 

 for their success in the world upon their ability to shift 

 from place to place, to find new o]:)enings, and to get in 

 and mature a crop of seeds before the perennials crowd 

 them out again. 



There are many beautiful and interesting flowers in the 

 sw^ale : yellow flowers, such as Saint John's wort, buttercups, 

 goldcnrods and loosestrife; blue flowers, such as monkey- 

 flowers, lobelias and gentians ; white flowers, such as meadow- 

 rue, turtleheads, avens and cresses; pink flowers, such as 

 cockle-mint, willow-herb, fleabane and marshmallows ; red 

 swamp-lilies and flaming scarlet cardinal -flowers ; and others 

 in great variety and in continual succession. Forms like those 

 that grow on shoals (mentioned on page 35) will appear if there 

 be pcmiancnt 0])cn water. Indeed, a careful study of even 

 a small swale might discover the presence of a hundred or 

 more plant species. Ten or a dozen of these are likely to be 

 found to comprise the greater bulk of the plant po]nilation. 

 The dominant species are mainly those having comparatively 

 simple and inconspicuous flowers, w^hose pollen is distributed 

 by winds. The dominant species extend their domain chiefly 

 by strong vegetative offshoots, occui)y the soil with strong 

 roots, and never let go. 



