364 Prairie Flora 



when the prairie grasses have taken on the brown tints due to frosts. 

 The prairie is now whitened with Aster multiflorus and its allies. It 

 is easy to find plants which may be called Aster exiguus, (Fernald) 

 Rydberg, and on the plains of South Dakota are plenty of forms that 

 may be called Aster comutatus, of Torrey & Gray. However there 

 seems to be so many connecting forms that it seems about as well to 

 call the whole group Aster multiflorus. 



2. The Slough Flora, 



Perhaps the earliest spring flowering plants of the prairie sloughs 

 and marshes are the water crowfoots. When the water is low Ranun- 

 culus delphinifolius is found blooming in muddy places in the latter 

 part of May, or if the water is high, it will be found a little later 

 blooming in the water itself. Ranunculus abortivus is found in moist 

 places at about the same time, and Ranunculus sceleratus soon follows. 

 In deep sloughs and in the still waters of rivers Ranunculus circinatus 

 and Ranunculus aquatilis are seen showing their white flowers in June. 

 An Eleocharis which seems to be E. palustris glaucescens may be seen 

 growing in shallow water or in wet places early in June. Scirpus 

 fluviatilis and Scirpus polyphyllus, together with Juncus nodosus, Jun- 

 cus lurida, Carex festucacea, Carex arcta, Carex cephaloidea, Garex vul- 

 pinoidea and Carex gravida furnish much of the grass-like vegetation 

 of the sloughs in June. In the shallow water of creeks a true grass, 

 Alopecurus geniculatus, may be found showing its timothy-like heads. 

 In deeper water the common cat-tail, Typha latifolia, may be seen. 

 The tuffted loose strife, Lysimachia thyrsiflora, may be found nestling 

 among the reeds and grasses, and in deep open water^ that reptile-like 

 appearing plant, Hippuris vulgaris, may frequently be found. Another 

 plant found in the sloughs in June, is Steironema lanceolatum. It is 

 toward the close of June, too, that the only shrub common to the 

 sloughs. Spiraea salicifolia, is in bloom. 



With the beginning of July another loose strife, Steironema cilia- 

 turn, is in bloom. It was on July 12th, 1888, that the writer collected 

 Bacopa rotundifolia in a prairie slough in Lac qui Parle county, per- 

 haps the only Minnesota collection ever made of this plant. Another 

 slough plant to be looked for in July is Lycopus americqnus. The 

 arrow heads, Sagittaria latifolia and Sagittaria cuneata are now in 

 bloom and Scirpus lacustris and Scirpus americana are fruiting in 

 rather deep sloughs, along with Sparganium eurycarpum. 



With the beginning of August the swamp milkweed, Asclepias in- 

 carnata, begins to bloom in grassy sloughs. Bcrula erecta is found 

 in slow streams while Cicuta maculata and Siu7n cicutaefolium are 

 found in deeper water. With the drying up of the sloughs in August 

 several species of Potentilla become noticeable. Some of these are 

 clearly Potentilla monspeliensis, others appear to be Potentilla pen- 

 tandra, while still others may be Rydberg's Potentilla leucocarpa. It 

 is in August too, that Pedicularis lanceolata is in bloom, while Radi- 

 cula hispida and Radicula palustris are common in muddy places. 

 This plant has been called Nasturtium and Roripa. Phragmites com- 

 munis is now waving its shining purple panicles in the deeper sloughs, 

 and in springy and boggy places the great water dock, Rumex hrit- 



