19 



3. Lemna perpusilla Torr. Fig. 6, Map 13 



Rare in quiet waters of southern New England. Range extends 

 from Massachusetts and Connecticut west to New York, Ohio, Illinois, 

 and Nebraska, south to Florida, Louisiana, and Texas; nearly 

 worldwide. 



4. Lemna minor L. Fig. 6, Map 14 



Common in New England, occasionally in brackish water along 

 the coast. In eastern Massachusetts this species is often associated 

 with highly eutrophic or polluted waters. Range extends from 

 Newfoundland, St. Pierre et Miquelon, and southern Labrador west to 

 British Columbia, south to Florida and southern California; Mexico, 

 worldwide, 



2.5-127.0 mg/1; (46) 



alkalinity: mean 36.2 mg/1; range 

 pH: mean 7.2; range 6.1-9.5; (43) 



Literature Cited and 

 Selected References 



Blake, C. H. 1938. Wolff iella floridana in Massachusetts. Rhodora 40: 76. 



Brooks, J. S. 1940. The cytology and morphology of the Lemnaceae. 

 Ph.D. thesis, Cornell University, Ithaca, NY. 



Clark, H. L. and J. W. Thieret. 1968. The duckweeds of Minnesota. 

 Michigan Bot. 7: 67-76. 



Cody, W. J. 1980. Wolffia columbiana (Lemnaceae), Water-meal, new to 

 Manitoba. Canad. Field-Naturalist 94: 193-194. 



Colt, L. C, Jr., C. B. Hellquist and W. J. L. Zubrin. 1971. An interesting 

 association of rare aquatic plants from New Hampshire. Rhodora 

 73: 296-299. 



Countryman, W. D. 1968. Wolffia in New Hampshire. Rhodora 70: 491. 



Daubs, E. H. 1965. A monograph of Lemnaceae. Illinois Biol. Monogr. 

 University of Illinois Press. Urbana. 118 pp. 



Dore, W. G. 1957. Wolffia in Canada. Canad. Field-Naturalist 71: 10-16. 



Gilbert, H. C. 1937. Lemnaceae in flower. Science 86: 308. 



Goebel, K. 1921. ZurOrganographiederLemnaceen. Flora 114:278-305. 



Harrison, D. 1964. The taxonomic significance of the effect of 

 nutrient media, photoperiod, and light intensity on the morpho- 

 logical features of the genus Spirodela Schleid. M. S. thesis. North 

 Carolina State University, Raleigh, NC. 



