ECOLOGICAL CROSS SECTION OF THE MISSISSIPPI. 199 



The prairie. 



The prairie flora on the Illinois side does not differ materi- 

 ally from that on the Missouri plateau. In spring a number 

 of grasses make their appearance, especially Agrostis albaj 

 A. scabra, Danthonia spicata, Elymus striatus^ Phleum pra- 

 tense and Poa pratensis. Rosette-forming species appear 

 along with these. Capsella Bursa^pastoris, Sisymbrium of- 

 -ficinole, Oenothera hienniSy Erigeron annuuSy E. canadensis 

 and E. philadelphicuSy Taraxacum offidnaley Veronica arven- 

 sis, Verbena stricta and V. urticaefolia are among the most 

 frequent and most striking. Other species appearing at this 

 time are Anemonella thcdictroideSy Ranunculus fascicularisy 

 Draba carolinianay Geranium carolinianumy Oxalis strictay 

 Polygcda verticillatay Amorpha canescenSj Astragalus mexi" 

 canuSy Stylosanthes elatioTy Triosteum angustifolium and 

 T. 'perfoliatumy Houstonia angustif alia y Chrysopds villosay 



pit 



'.foliumy Silphium integrifolium y and j 

 ctically form the spring flora together 

 3 rosettes have been striking features 



ing the winter months. Among them Lechea major and L. 

 minor, Achillea Millefoliumy Cnicus pumilus and Plantago 



Rugel 



i are to be noted especially. Nor should mention of 

 esence of clumps of OpurUia Rafinesquii and of Monarda 



fistulosa be omitted. 



The summer sees a large addition to the species above 

 mentioned, the new species being derived especially from 

 the Leguminosae and Compositae as shown by the distri- 

 bution tables. During the autumn Compositae are most 

 prominent, especially several species of Aster and Solidago. 



Introduced Plants. 



The introduced 



I.e. 



inity of dwellings, in parks and 



on the railroad right of way. Among the railroad immigrar 

 must be placed the following: Clematis crispa (S. U. S 

 Argemone alba (W. and S. W. U. S-), Argemone platyceras 

 and S. W. U. S.), Sisymbrium altissimum (S. U. S.), Cleoi 

 inicgrijolia ''W. U. S.), Polanida graveolens (brought to t] 



