ECOLOGICAL NOTES ON THEMUSCA TINE FLORA. 183 



It is curious that this plant does not occur far distant from the road- 

 bed. For nearly nine miles it forms two yellow streaks, one on each 

 side of the road-bed. Occasionally one meets with Helianthus annuus; 

 this, however, is also an introduced plant of long standing. The for- 

 mer, Mr. Reppert informs me, has been naturalized some eight or nine 

 years. Polygomiui tcnuc, a strictly xerophytic plant, grows in spaces 

 between the bunch grasses. /'. ramosissimuiii is more widely distrib- 

 uted and occurs abundantly in fields and along the railroads. Aster 

 jnultijforus, with its strong perennial rhizomes, grows profusely in 

 places. The more beautiful A. scriccus grows in isolated patches 

 among the bunches of Andropogon nutans. Aster oblongifolius, which 

 is less common in Iowa, grows in sandy soil on more elevated places. 

 It is southern, like many other plants of the island. Liatris pycnostachya 

 grows in profusion hardly less vigorous than specimens on hills of 

 central Iowa. There are but three common shrubby plants on the 

 island — Rhus aroinatiea, RJius toxicodendron and Ceanotlms ovatus, re- 

 ferring of course to those most widely distributed on the sandy plain. 

 All of these shrubs grow in masses, the Rhus aronmtica most profusely. 



Dune Vegetation. — These sand dunes, as elsewhere in' the State, 

 are marked by drifting sands where they are not covered with vegeta- 

 tion. They are not all of equal height, and in some cases they are but 

 slightly different from the surrounding prairie land. One of these 

 dunes near Fruitland is marked by the abundant growth of Brezveria 

 Fickeringii, which is considerably out of its range. Otherwise the 

 sand dunes are marked by the abundance of Cenchrus tribuloides and 

 Bouteloua hirsiita, both species admirably adapted to prepare the soil 

 for gaining more humus. Couiuielina Virginica is not uncommon on 

 these dunes and elsewhere on the island. Its occurrence here is quite 

 as remarkable as the presence of Breweria. 



Hydrophytic Plants. — The larger and smaller bayous are often 

 filled with a vigorous growth of Scirpus lactistris, Pliraguiites communis 

 and Glycerin fluitans. The latter frequently forms small islands. 

 Sagittaria calycina, large and vigorous specimens, is abundant in 

 places. Of the other hydrophytic species collected by Mr. Reppert I 

 may note >S". heterophylla, S. graminea, S. variabilis and the var. 

 obtusa ; Myriophyllum seabratum in shallow ponds; Azolla Caroliniana, 

 found by Mr. Reppert in Muscatine slough. NymphcEa tuberosa 

 abounds in these sloughs. Nuphor advena is abundant in the brackish 

 sloughs in many places on the island. In running sloughs Elodea 

 Canadensis occurs, and Lemna minor is common on the surface of the 

 water everywhere. 



Semi-hydrophytic Plants. — The most conspicuous is the Cardinal 

 flower {Lobelia cardinalis), but there is also Lobelia syplilitica, Mimu- 



