TRAPACEAE 



Trapa (Water Chestnut) 



Floating annual, with slender roots; submersed leaves opposite, 

 finely dissected; floating leaves alternate, blades rhombic, petioles 

 inflated; flowers white, axillary among floating leaves; fruit a large 

 "woody" nut or caltrop with four sharp barbed spines. 



1. Trapa natans L. Fig. 1, Map 1 



Locally abundant, sometimes forming large floating mats, in 

 southern Lake Champlain, Vermont, and in the Sudbury and Concord 

 Rivers, and the Great Meadows National Wildlife Refuge, Concord, 

 Massachusetts. A native of Eurasia, this species has become a nox- 

 ious weed in the waters where it has become established. This taxon 

 was first introduced into North America about 1874 and was culti- 

 vated in Asa Gray's botanical garden at Harvard University in 1877. 

 By 1879 it had escaped to nearby Fresh Pond, Cambridge, Massachu- 

 setts (Countryman, 1977). Range extends from Massachusetts to 

 western Vermont, eastern New York, Maryland, and Virginia. 



alkaHnity: mean 37.7 mg/1; range 12.0-127.5 mg/1; (5) 



pH: mean 7.1; range 6.7-8.2; (5) 



Selected References 



Countryman, W. D. 1977. Water chestnut {Trapa natans L.) in Lake 

 Champlain. Proc. Lake Champlain Basin Environmental Con- 

 ference, Miner Center, Chazy, New York 4: 3-10. 



Countryman, W. D. 1978. Nuisance aquatic plants in Lake Cham- 

 plain. New England River Basins Commission, Burlington, VT. 

 Lake Champlain Basin Study Tech. Rep. No. 23. 102 pp. 



Muenscher, W. C. 1934 [1935]. Aquatic vegetation of the Mohawk 

 watershed, pp. 228-249 in: A Biological Survey of the Mohawk- 

 Hudson Watershed. New York State Dept. Conserv. Suppl. Ann. 

 Rept. 1934. 



Smith, R. H. 1955. Experimental control of water chestnut {Trapa 

 natans) in New York State. New York Fish and Game J. 2: 

 173-193. 



Winne, W. T. 1935. A study of the water chestnut, Trapa natans with a 

 view of its control in the Mohawk River. M. S. Thesis. Cornell 

 University, Ithaca, New York. 



