136 Karl M. Wiegand and Arthur J. Eames 



1. Spirodela Schleid. 

 1. S. polyrhiza (L.) Schleid. 



Floating on the quiet waters of ditches, marshes, and ponds, in waters not strongly 

 calcareous ; common. 



N. S. to B. C., southw. to Fla., Tex., N. Mex., Nev., and s. Calif. ; infrequent on 

 the Atlantic Coastal Plain. Found also in tropical Am. and in the Old World. 



2. Lemna L. 



a. Fronds stipitate, remaining attached in a zigzag chain, wholly submerged. 



1. L. trisulca 

 a. Fronds not stipitate, quickly becoming detached, floating on the surface. 



2. L. minor 



1. L. trisulca L. 



Ponds, ditches, and quiet bays, especially abundant in cattail marshes ; frequent. 



The larger marshes about Cayuga Lake ; along the shores of Cayuga Lake ; 

 Summit Marsh (D.l) ; Jennings Pond (D.). 



N. S. to B. C., southw. to N. C, Ala., Tex., N. Mex., and Calif. ; apparently 

 not found in noncalcareous regions, and hence rare or absent on the Atlantic Coastal 

 Plain. 



2. L. minor L. 



Floating on the quiet waters of ditches, marshes, and ponds, in waters not strongly 

 calcareous ; very common, and widely distributed. 



Throughout N. A. except in the extreme North ; also widely distributed over the 

 world. 



3. Wolffia Horkel 7 



a. Fronds subglobular, coarsely cellular, submerged. 1. W. columbiana 



a. Fronds ellipsoidal, finely cellular, floating on the surface. 2. W. punctata 



1. W. columbiana Karst. 



Quiet waters of sloughs, ponds, and the larger marshes, with no apparent reference 

 to lime content ; occasional. 



Ringwood, 1923; Dryden Lake, 1916; cut-off from Red Mill Pond, Freeville, 1918; 

 Cayuga Marshes, w. of Cayuga Bridge (D.l) ; Montezuma Marshes, near the " Marl 

 Works" (£>.); May Point (D.) ; Pout Pond, 1922. 



Conn, to Minn., southw. to Fla. and La. ; infrequent on the Coastal Plain. Found 

 also in Mex. and S. A. 



2. W. punctata Griseb. (IV. brasiliensis of many authors.) 



With the preceding species, w. of Cayuga Bridge near the Seneca Canal from 1894 

 to 1898 ; not seen recently ; lime requirements not known. 

 Ont. to Mich., southw. to Tenn. Found also in Jamaica. 



22. COMMELINACEAE (Spiderwort Family) 

 1. Commelina (Plum.) L. 

 1. C. communis L. Dayflower. 

 A weed along roadsides and in waste places in rich soil ; scarce. June-Sept. 

 In the Cayuga Lake Basin, known only about Ithaca : n. of L. V. R. R. station ; 

 Cascadilla Place, n. side ; Quarry St. ; Veterinary College grounds ; garbage dump, 

 lighthouse road ; and elsewhere. 



N. Y. to Kans., southw. to Fla. and Tex. ; recently adventive at Ithaca from 

 farther south, and spreading. Native of Asia. 



7 Wotfia Hork. and Wolffia Hork. ex Schleiden are different names, according to the International 

 Code. While Wolfia is antedated by two other uses of the name, Wolffia is not antedated and is the 

 oldest valid name of the present genus 



