ECOLOGICAL CROSS SECTION OF THE MISSISSIPPI. 



195 



bluff and in a comparatively dry situation, the former passes 

 through the lowland at a distance from the hills. Besides, 

 the railroads tap entirely different sections of the country 

 and consequently one finds differences in the species of intro- 



be 



by grasses, chiefly 



pratensis, with which Agropyrum repens, Agrostis alba and 

 several other grasses are associated. The spring brings with 



sella Bursa-pai 

 tusum, Sisymb 

 Trihulus arana 



IS Myosurus minimus, Corydalis aurea, Cap- 

 ons, Lepidium intermedium, Nasturtium ob- ■ 



H 



um altissimumy S. canescens, S. officinale, 



mndiflorus, various clovers^ Mollugo verticillatay 



nceolataj P. patagonica aristatay P. Rugelii and P. 



Rosettes of Oenothera biennis, Stellaria media, 



Lactuca Scariola, L. Scariola integrata and Verbascum Thapsus 



to time* The occurrence of Lilium 



mrgimca 



from time 



canadense is to be noted. The summer adds Portulaca ole- 



raceGj Bergia texana (rare)^ several Legu 

 Cassia Chamaecrista, Dalea alovecur aides. J 



such 



as 



Medicago sativa, Melilotus alba and M. officinalis, as 



Compositae, m 



A, trifda, Helianthus 



H 



in some places takes entire possession, Solanumcaro 

 Amaranthus albiis, A. blitoides and A. retroflexus, 

 capitatus, Euphorbia humistrata, Setaria glauca, S. itolica 



Croton 



from 



Mays 



Linaria 



Kali 



Bottom 



closing the railroad as there is along the Missouri bluffs, fences 

 separating it from the adjacent cultivated fields. Along these 

 fences hedges frequently are formed, composed of brambles, 

 together with Cassia Chamaecrista, Tecoma radicans, and 



Toxicodendron 



amencana 



infrequent. The railroad ponds do not offer features distinct 

 from those on the Missouri side, except for the occurrence of 

 Nelumhium luteum, Utricularia biflara and Echinodorus radi- 



cans. 



