Jennings : A Botanfcal Survey of Presque Isle. 333 



In the Andropogo7i furcatus consocies — (see Plate XXXV) 



Ltipinus perennis, Panicum Scribneriarnim, 



Asclepias syriaca, Lithospermiwi Gvielini, 



Geaster hygrometriais. 



In the Stenophyllus capillaris consocies — 



Cyperus filiailmis, Marasmius sp. 



In the Sorghastrum nutans consocies — 



Fragaria virginiana. 



The Myrica Thicket Formation. 



Next following the Panicuin-Artemisia formation comes the thicket- 

 formation, composed of small trees and shrubs, which is in its turn 

 to be finally replaced by a forest-formation. The thicket in this suc- 

 cession is the homologue of the heath in the succession previously 

 described. It begins at about the same distance from the lake, in 

 soil of about the same age, and is, similarly, to be finally replaced 

 by a forest. This formation at Presque Isle may be called the Myrica- 

 thicket-formation, its facies being the wax myrtle, Myrica carolinensis. 



Myrica carolinensis apparently cannot at once accomplish ecesis in 

 the upper layers of dry, loose sand, such as are occupied by the Pani- 

 cum-Arteviisia, the Andropogon furcatiis, or the Cladonia consocies, 

 but in the other consocies of the formation, especially in the finer, 

 moister soil occupied by the Stenophyllus capillai-is or the Sorghastrum 

 nutans consocies, the waxy Myrica drupes can successfully sprout and 

 give rise to healthy plants. From these plants as centers the Myrica 

 may by vegetational reproduction and dissemination invade the 

 dryer soils of the first mentioned consocies. Young shoots of the 

 Myrica arise in a radial zone all about the parent plant, having their 

 origin both in lower limbs, which may have become buried in the 

 sand, and also from subterranean branches. 



In this manner the Myrica carolinensis consocies may in the course 

 of a few years successfully occupy quite extensive areas, displacing 

 not only the Stenophyllus and Sorghastrum, but also the consocies of 

 more xerophytic habit. 



Principal Species of the Myrica Thicket-formation. — 



Primus serotina, Rubus allegheniensis, 



Prunus pennsylvanica, Fragaria virginiana, 



Prunus virginiana, Celastrus scandens, 



Solidago canadensis. 



