A REVISION OF THE AMERICAN LEMNACEAE, 35 
Lemna cycLostasa (Ell.) Chev. Fl. Par. 2: 256. 1827. 
Schleid. Linnaea. 18: 390.1839. Lemna minor var.? 
Cyclostasa Elliott, Bot. S. Carol. and Ga. 2: 518. 1824. 
L. Valdiviana Ph. Linnaea. 33: 239. 1864. JL. 
Torreyt Aust. in Gray, Man. Bot. 479. 1867. [5th ed.]. 
L. abbreviata Hglm. Engler’s bot. Jahrb. 21°: 298. 
Jan. 1895. 
Fronds solitary or grouped, more commonly 2-8 cohering 
in a more or less curved chain; oblong to obovate-oblong ; 
usually somewhat falcate, particularly in the smaller fruit- 
ing plants; .7-1.5 mm. wide by 2.3-4.5 mm. long; base 
usually strongly unsymmetrical, tapering into a short stipe 
or frequently sessile; cavernous in the middle portion only. 
Roots long; rootsheath large, thin, cylindrical; rootcap 
variable in length, usually long. Fruit slightly unsymmet- 
rical, elongated ovate, pointed by the long straight or 
sometimes curved style; usually half the length of the 
frond; seed oblong-ovoid, with thick coat particularly at 
the apex, 12-29 ribbed, abundantly transversely striated.— 
An American species growing abundantly in our range from 
the Atlantic to the Pacific oceans, absent only in the northern 
part, extending southward into South America.— Plate 3C. 
The variableness of this species in the form of its fronds 
has given rise to many varietal and even specific names, but 
though frequently one individual may be remarkably differ- 
ent from another, yet I find no constant difference in any 
one particular that I would feel justified in recognizing a 
variety by, and furthermore [I find all gradations of forms 
between the extremes. One such variation reported as a 
variety and later as a doubtful species is Hegelmaier’s 
Lemna ( Valdiviana var.) abbreviata, which I recognize 
only as a more symmetrical form of the species. 
Specimens examined from Massachusetts (Kennedy, 1894; Deane, 
1894); Rhode Island (Osterhout, 1893-94); Connecticut (Evans, 1889; 
Eames, 1895—both exceptionally large plants); New York (Torrey; 
Leggett, 1870; Young, 1873); New Jersey (Austin, 1862); South Caro- 
lina (Ravenel, 1850); Georgia (Ravenel, 1881; Schweinitz); Florida 
(Garber; Canby, no. 16, 1869; Ravenel, 1877; Nash, no, 894, 1894); Ohio 
(Hacker, 1895); Illinois (Engelmann, 1838); Missouri (Bush, 1895; 
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