3 2 ° 
The Ohio Naturalist. 
[Vol. VIII, No. 6, 
The successor to the Andropogon Dune Formation may be 
one of several different structures. In the formation are often 
to be found invaders, of the following species: Primus virginiana, 
Juniperus virginiana , Parthenocissus quinquefolia, Arctostaphylos 
uva-ursi, Ptelea trijoliata , Toxicodendron pubescens, Tecoma 
radicans, so that the succeeding stage may be expected to be 
either a heath or a thicket. The larger part of the vegetation in 
the middle of the Dune Section corresponds closelv to the vege¬ 
tation of Cowles’ “Dune Complex’’ of the Lake Michigan dune 
Fig. 8. A miniature dune formed about a clump of Panicum virgatum, 
in a large blowout to the north of the Lake Laboratory. 
region, and the instability of the sand is here such that a genetic 
series of the formations is a very difficult problem. However, it 
appears to the writer that the following formation would nor¬ 
mally succeed the grass dune formations in the vicinity of the 
Lake Laboratory: 
The Prunus-Rhus Dune-Thicket Formation. 
Facies: Prunus virginiana , 
Rhus aromatica , 
Ptelea trijoliata. 
Principal Species: Tecoma radicans. 
