STllUCTURE OF THE FORMATION 79 



leafy plants are scarcely observed after flowering. The white 

 fringed orchis is perennial by means of thick, fibrous roots. 

 Hahenana hracteata is a rare, inconspicuous plant found 

 only once in the meadows. Thalictrum purpurascens is a 

 leafy, tall-growing perennial, the numerous male plants of 

 which are especially prominent in the aspect during anthesis. 

 At this time the staminate racemes are one mass of yellow, 

 linear anthers, which give off a cloud of "pollen dust" at the 

 least movement. The flowers are anemophilous and dio- 

 ecious, xenogamy alone being possible. By far the m«st 

 showy flower in the entire prairie is Liliuin canadense. Its 

 erect, leafy stems are about one meter high and terminate 

 with a single large, nodding blossom, bright orange in color 

 and beautifully spotted with brown. The lily is perennial 

 by means of scaly bulbs developed from a short, stout root- 

 stalk. Equisetum laevigatum is one of the two fernworts of 

 meadows, E. arvense being the other. E. laevigatum occurs 

 at two stations in the low meadows, and ranges from 44-260 

 individuals to the quadrat. Its dark green, jointed stems are 

 hardly to be distinguished from the coarser facies. Equise- 

 tum is a perennial with deep-seated rootstalks, from which 

 frequently many stems develop. 



Scirpus atrovirens and Phalaris arimdinacea are hydro- 

 philous species of the wet meadow. Scirpus develops short 

 rootstalks, by virtue of which it forms dense clumps a few 

 meters in extent. The dark green foliage and the brown 

 umbels render the clumps of this species prominent in mead- 

 ows. The flowers are proterogynous, allogamy being the pre- 

 ferred method of pollination. Phalaris is a tall-growing per- 

 ennial grass, forming rather indefinite bunches of several 

 dozen individuals. Anthesis takes place during June and is 

 immediately followed by maturation. The seeds are soon 

 thrashed out of the dry panicles with the wind. Scirpus 

 atrovirens and Phalaris arundinacea are almost invariably 

 associated with Cicuta maculata, Asclepias incarnata, and 

 Lythrum alatum. Apocynum cannahinum occurs sparsely 



