POTAMOGETONS IN REI.ATION TO POND CULTURE. 261 



GENERAL SURVEY OF LIFE CONDITIONS OF THE SPECIES INVESTIGATED. 



POTAMOGETON AMERICANUS. 



This species, which has been grown from seed and cultivated through two succes- 

 sive seasons, will receive more specific treatment later under the caption "Natural 

 and artificial propagation." In its natural habitat this plant has been observed 

 growing near the mouth of Fall Creek, a tributary of Lake Cayuga, and in a near-by 

 cove of the lake, at varying depths of 3 to 4 feet. It has been observed also at Spencer 

 Lake, at about the same depth but in much swifter water. In the latter situation 

 the blades of the leaves are conspicuously attenuated. According to Fryer (1900), 

 who has obser\^ed this plant in various localities, it is a plant of upland streams and 

 rivers rather than of stagnant waters. 



By uprooting the entire plant in the growing season, it is found that the stem 

 springs from a rootstock that is deeply anchored in the mud, where new shoots radiate 

 horizontally from the estabUshed parts of the plant. During the summer these young 

 rootstocks produce large buds at their tips (fig. 6). After the plant dies down, which 

 may occur as early as August, the subterranean system remains intact for several 

 weeks. The new rootstocks, however, carrying the buds at the tips, become eventually 

 detached through the disorganization of the parent stem and in time die away, leaving 

 but little beyond the isolated buds to perpetuate the plant the following spring. Such 

 buds, since they remain in a quiescent state during the winter, may be called winter 

 buds or hibernacula, a term applied to structures of a similar nature and function. 

 Mr. A. J. Pieters (1901) doubtless referred to propagative structures of this kind when 

 he recorded for P. americanus (P. lonchites) "extensive runners bearing buds at their 

 ends," though no figures are given and no further observations are noted. 



Fryer (1888) mentions an autumnal state of P. americanus (P. fluitans) in which 

 the leaves are all narrowly linear or grasslike. These later growths, he says, are 

 developed in the axils of old leaves during the natural decay of the lower part of the 

 stem. They are ultimately set free as fascicles of narrow leaves which, after rootlets 

 are formed at the base of the new growth, sink to the bottom and continue the life of 

 the species. Such structures, which would be analogous to the winter buds of P. ohtu- 

 sijolius and P. zosterif alius, have not been observed in P. americanus under investiga- 

 tion, though they may have been overiooked in the changes of water level during the 

 autumn. 



POTAMOGETON AMPLIFOUUS. 



This is an American species distributed quite generally throughout the continent. 

 It forms large patches in the open vegetation but thrives also in close association with 

 P. Robbinsii, Heteranthera dubia, Ceratophyllum demersum, Elodea canadensis, and 

 other plants of aquatic meadows. As a forage plant it may be regarded as one of the 

 best, growing continuously from early spring to late fall or early winter and producing 

 an abundant herbage by reason of its numerous large leaves. The rankest growths 

 have been found in the more quiet waters of Lake Cayuga and "The Pond" at North 

 Fairhaven, at depths of 5 to 7 feet, in a substratum of mud rich in vegetable mold. 

 Propagation is rapid. The dense patches of stems, more or less unbranched, arise in 

 great numbers from an intricately developed subterranean system ffig. 7). This 



