Minnesota Plant Life. 



215 



Many bulrushes have three-cornered stems and grow in 

 marshes or even upon prairies, but these are to be connected 

 with the ordinary cylindrical bulrush of lakeshores because 

 of the exact similarity of their flowers and fruits. Indeed., the 

 three-cornered stem was probably primitive and the cylindrical, 

 adaptational. 



Carex-sedges. The largest genus of plants in Minnesota 

 — after the rusts — belongs to the sedge family, and there are 

 about 1 10 species of Carex in the state. The Carices are grass- 

 like sedges, for the most part small and slender plants and per- 

 ennial by underground rootstocks. Each pistillate flower de- 

 velops a sac-shaped leaf which 

 incloses the rudimentary fruit, 

 so that when ripe it stands in 

 a little bladder, reminding one 

 somewhat of the ground- 

 cherry, only very much smaller. 

 These sacs may be either pa- 

 pery or hard and they may be 

 either smooth, furrowed or 

 winged. Usually the stigmas 

 are protruded far beyond the 

 top of the sac which itself takes 

 the form of a bottle, and 

 through the neck of this the 

 stigmas are thrust. Some- 

 times the stigma is two-lobed, 

 while in other species the number of the lobes is three. A con- 

 siderable variety exists in the shape of the sac in which the fruit 

 is formed. Sometimes it is slender, while again it is swollen 

 or even globose. In many sedges the pistillate flowers — their 

 fruit-rudiments inclosed in the sacs — are displayed in special 

 spikes or heads, while the staminate flowers stand in other spikes 

 above or below the pistillate — if the two occur on the same 

 general axis — or entirely separate from them. Among the 

 Carices the flower clusters, in their general shape and in their 

 position on the plant-body, show great variety. Sometimes 

 they are cylindrical and pendulous, again cylindrical and erect 

 or ascending, again globose or loosely aggregated. In stdl 



Fig. 9(3 Carex-sedge. After Britton and 

 Brown. 



