ECOLOGICAL CROSS SECTION OF THE MISSISSIPPI. 165 



flata and L. leptostachys, Apocynum androsaemifoliuvij As- 

 clepias tuherosa and A . vertidllata^ as well as Verbascum Thap- 

 suSj Sabbatia angiilaris^ Cunila Mariana and Monarda Brad- 

 buriana are prominent, while in late summer and early fall 

 the Compositae seem to occupy the entire space, though 

 Monarda punctata remains in bloom till late in the year. The 

 autumn vegetation is made up mainly of Aster patens , A. 

 turbinelluSj Helianthus ocddentaliSj Rudbeckia triloba and 

 Solidago rigida. In summer Juncus tenuis^ Carex oligocarpa^ 

 Agrostis olba, Danthonia spicata^ Festuca tenella^ and Pani- 

 cum depauperatum are everywhere. Two ferns, Aspidium 

 niarginale and Pteris aquilina^ are found from spring till 

 autumn/ 



Limestone glades. 



Limestone glades are rather frequently occurring areas 

 of small scope, ordinarily of great elevation, where the surface 

 is but little incHned. As a result of these conditions the 

 e;rcater part of the soil formed is washed away by heavy 



limestone 



sufficient to carrv off most of 



draina 



time 



the 



by 



ground channels, and lost to the plants of the limestone glade. 

 As a result, such locaUties have a limited flora at best. They 

 are usually covered with an excessive growth of Sassafras 

 officinale^ represented by numerous small trees, probably 

 suckers, originating from the few older trees occurring there. 

 The reason that so few of the latter are met with in similar 



system 



probably 



the trees can not secure a sufficient foothold to withstand the 

 early summer storms, occurring at a time when the ground 

 is greatly softened. Evidence of this is found in the stumps 

 and rotting sassafras logs, so often met with in limestone 

 glades. Besides sassafras there is very little woody growth, 

 it beine: limited to Rhamnus lanceolata and Diospyros vir- 



