8 ROCHESTER ACADEMY OF SCIEN T CE. [Oct. 8, 



and Lemna cover the stagnant waters in coves and in openings among 

 the flags. Nymphaa rent for mis, Utricularia vulgaris and Valisneria 

 are common. Naias marina is abundant in some of the coves on the 

 west side. Sparganium minimum is found in our district only here. 



GENESEE RIVER. 



The walls of the ravine of the Genesee river below Rochester are 

 vertical rock-walls of sandstone, shale and limestone, about 200 feet 

 high, with heavy talus on the radial side of the river curves. In the 

 southern part of the city the river flows in a shallow channel in the 

 Niagara limestone. Above the city the river flows in a bed of drift 

 with broad flood-plains. 



The river and its banks have been a peculiarly rich field for the 

 botanist, including as they do plants belonging to the aquatic flora as 

 well as those of upland growth. Mr. Joseph B. Fuller, who has prob- 

 ably explored this region more thoroughly than any other collector, 

 excepting Dr C. M. Booth, reports that in the territory between Vin- 

 cent Place bridge and Hanford's Landing, a distance of two and a 

 half miles, he has found five hundred species of plants. We doubt if 

 a better record can be shown anywhere for the area covered. The 

 growth of the city has undoubtedly destroyed some of the species, 

 but the most of them can still be found. 



MEN DON PONDS. 



The Mendon ponds lie among a group of sand and gravel knolls* 

 about twelve miles south-east from Rochester. They are five in num- 

 ber, the smallest covering only a few acres, the largest having an area 

 of over one hundred acres. Four are connected by creeks or marshes, 

 and form the head of Irondequoit creek. A fifth is apparently with- 

 out outlet. Some sphagnum bogs represent other former ponds. 

 The margins of the ponds are generally low and marshy. Sphagnum 

 grows here luxuriantly, forming a bed for large numbers of Sarra- 

 cenia, Drosera, Calopogon, and many other species. The land adjoining 

 is under cultivation, but some low borders and hillsides are covered 

 with forests which contain nearly every species of tree found within 

 the district. The tupelo is represented by several large, fine trees. 

 Black spruce is reported within the county only at this point. A char- 

 acteristic feature of this locality is the occurrence of thousands of 

 plants of species which are elsewhere scarce. Acres of marsh are 



*See page 35. 



