OF ARKANSAS. 323 



Marigold, the Water-cress, probably also introduced, the Penny-wort, the 

 Water-Parsnip, and some other species.* 



Some of these plants, especially the Pond-weed (Potamogeton compres- 

 sus, L.), the Water Persicaria, the American Brooklime, grow in the bed 

 of Spring River, below the bed of the Mammoth Spring. The cattle of 

 the vicinity greedily feed on them, and thrive finely, though spending 

 whole days in water. The two last species of plants, when growing on 

 wet soil, as they generally do, and under atmospheric influence, are some- 

 what bitter, hard, and scarcely touched by the cattle. Under water they 

 are subjected, by deprivation of a full light, to a kind of chlorosis or etio- 

 lation, which renders them tender and nutritive. The Indian rice and the 

 Eice cut-grass grow also below the dam along the muddy banks. 



I truly regret that it does not come within my province to dwell on the 

 natural beauty of the Mammoth Spring and of the hilly country surround- 

 ing it. The place will doubtless in the future acquire great importance as 

 affording a healthy and pleasant place of summer resort. 



PRAIRIES OF ARKANSAS. 



Before entering into the examination of the botanical distribution charac- 

 teristic of the part of Arkansas which I explored, there is still a peculiar 

 question which cannot be easily treated elsewhere, and which calls at once 

 for an examination. 



The Prairies of Arkansas do not appear to have been formed all in the 

 same manner. They are underlaid by different formations, situated at 

 various elevations, and their general aspect differs apparently so much, 

 that it looks as if a peculiar law had directed the formation of each of 

 them. 



I have explained elsewheref the general formation of the prairies, and 

 ascribed it to the agency of water. All the prairies still in a state 

 of formation along the great lakes of the North are nothing else but 

 marshes slowly passing to dry land by slow recession of water. When 

 land is continually covered by low stagnant water, its only vegetation is 

 that of the Rushes and of the Sedges. When the same land is alter- 

 nately subjected to long inundations and then to dryness, during some 

 months of the year, the same plants continue to cover it. By their de- 

 composition these marshy plants produce a peculiar ground, either black, 

 light, permeable when it is mixed with sand, as it is near the borders of 

 the lakes, or hard, cold, impermeable when it is mixed with clay or muddy 



* For Latin names and for other species of plants of the Mammoth Spring, see Catalogue of 

 the Plants of Arkansas. 



f Bulletin of the Society of Natural Sciences of Neuchatel (1856). 



