370 Annals of the Carnegie Museum. 



Aronia melanocarpa, Rubus hispidus, 



Eriophoriim gracile. 



From certain historical data it appears that half a century ago cran- 

 berries were abundant on Presque Isle. For the particular benefit of 

 the people of Erie, laws were passed by the State in 1841, impos- 

 ing a fine oi %\o to $25 for picking cranberries before October i, 

 "Cranberry Day." Probably the Sphagnum- Oxycoccus formation of 

 Cranberry Pond was formerly quite extensive. Around most of the 

 pond the shores have a gentle slope, and each formation is thus given 

 the opportunity to occupy a wide zone of fairly uniform ecological 

 conditions. At the present time the total area of the Sphagnuni- 

 Oxycoccus formation on Presque Isle probably does not exceed one- 

 half acre. Big Chimney Pond formerly contained considerable Oxy- 

 cocciis, but with the laying of the intake pipe for the Erie waterworks 

 this pond was dredged and later largely filled in with sand, so that 

 very little of the formation is left. 



The fate of the Sphagnum- Oxycoccus formation around Cranberry 

 Pond is easily to be recognized. There are many seedlings of /'/////x 

 strohus, Acer rubrum, Acet- sacchariniim, together with Spircea and 

 Aronia, so that eventually the zone will be sfipplanted by a forest. 



The Aronia- Poly trichum Formation. 



Skirting the outerand higher side of the Sphagnum-Oxycoccus forma- 

 tion around Cranberry Pond there is a zone consisting almost exclu- 

 sively of two species, the structure of the formation being as follows : 



Fades. — 



Polytrichan sp., Aronia nigra. 



Secondary Species, — 



Vaccinium corymbosutn, Populus tremuloides, 



Rubus hispidus, Prunus seroiina, 



Pr units virgifiiana. 



There is but a limited area of this zone, about one hundred feet 

 long by fifteen to eighteen feet wide, but the structure of the forma- 

 tion is very distinct and the plants occupy the habitat very completely. 

 The Aronia occurs in dense clumps (families and communities) be- 

 tween which the Polytrichum forms a matted heath. Of the second- 

 ary species there are a very few individuals present, these being mostly 

 seedlings and confined to the borders of the formation. 



