19 



7. Sparganium chlorocarpum Rydb. Fig. 9, Map 10 



E'ltremely common throughout New England. Erect plant of shal- 

 low waters and marshes or floating in deeper waters. Floating plants 

 are often confused with S. angustifolium. The best characters to 

 separate these two species are the fruit color and beak length. Plants 

 with narrow floating leaves (5 mm or less) in southern New England 

 are usually S. chlorocarpum. Much of our material would be referable 

 to var. acaule (Beeby) Fern., with shortened stems and contiguous 

 heads. However, we have noted that such plants frequently grow in 

 mixed populations with plants referable to var. chlorocarpum. Similar 

 observations have been made by W. C. Muencher and R. T. Clausen 

 (Clausen, 1934). We do not regard these as distinct varieties and there- 

 fore follow Voss (1966; 1972) in treating the former as forma acaule 

 (Beeby) E. Voss. Range extends from Newfoundland west to Ontario 

 and Minnesota, south to North Carolina, Pennsylvania, Indiana, and 

 Iowa. 



alkalinity: mean 17.2 mg/1; range 3.0-112.5 mg/1 

 pH: mean 6.9; range 6.2-7.8 



Literature Cited and 

 Selected References 



Beal, E. O. 1960. Sparganium (Sparganiaceae) in the southeastern 

 United States. Brittonia 12: 176-181. 



Clausen, R. T. 1937. A new variety of Sparganium americanum. 

 Rhodora 39: 188-190. 



Fernald, M. L. 1922. Notes on Sparganium. Rhodora 24:26-34. 



Harms, V. L. 1973. Taxonomic studies of North American Sparga- 

 nium. I. S. hyperboreum and S. minimum. Canad. J. Bot. 51: 

 1629-1641. 



Kaul, R. B. 1972. Adaptive leaf architecture in emergent and floating 

 Sparganium. Amer. J. Bot. 59: 270-278. 



Reveal, J. L. 1970. Sparganium simplex Huds., a superfluous name. 

 Taxon 19: 796-797. 



Voss, E. G. 1966. Nomenclatural notes on Monocots. Rhodora 68: 

 435-463. 



Voss, E. G. 1972. Michigan flora. Part 1. Gymnosperms and Monocots. 

 Cranbrook Institute of Science Bull. 55. Bloomfield Hills, Michi- 

 gan. 488 pp. 



