Jennings : A Botanical Survey of Presque Isle. 389 



There are two conspicuous aspects in the formation ; one determined 

 in mid-summer by the Cornus amoviufn, and the other in early autumn 

 by the So/idago canadensis society. 



The Ulmus-Acer Formation. 



The A/niis incana thickets are being invaded by the Ulmus-Acer 

 formation, which is here essentially as described for the preceding 

 succession, so that no further discussion of this formation need be here 

 given. 



The four ponds — Niagara Pond, Yellow Bass Pond, Grave- Yard 

 Pond, and Big Pond — each have large areas of the various stages of 

 the succession now under consideration, especially the rush vegetation 

 — Scirpiis formation ; and the reed and cat-tail marsh — Phragmifes- 

 Typha formation. The area dominated later in the season by the wild 

 rice, Zizania aqiiatica society, is especially large in these ponds, 

 excepting Big Pond, where somewhat more of the total area is taken 

 up by other formations. The shores of these ponds present various 

 phases of the two shrub-formations, but have mainly the Rhus-Alniis 

 formation. The shores towards the north and east sides of Yellow 

 Pond and Niagara Pond are more sandy and the formations are there 

 practically identical with those around the ponds and lagoons to the 

 north and east. 



T]ie Cove Habitat. 



The Cove Habitat comprises sheltered portions of the bay with 

 little or no current. The vegetation near the shore is that of the 

 Marsh Habitat, but in deeper water, one and one-half to two feet, the 

 Scirpiis formation is absent, its place being mainly taken by pond for- 

 mations. The structure of the vegetation is usually more or less of 

 a mixture of pond and marsh associations, the quieter water being 

 occupied by the pond-plants. The typical cove vegetation at Presque 

 Isle is essentially as follows : 



(rt) Chara formation, 



{b) Potamogeton formation, 



(<:) Castalia-Nymphcea formation, 



(^/) Phragtnites-Typha formation, 



(<f) Rhus-Alnus formation, 



(/) Ulmus-Acer formation. 



Owing to the lack of proper facilities for the work no extended 



