A REVISION OF THE AMERICAN LEMNACEAE. 39 
variety from Mexico city collected by Louis Hahn in 1868 
and determined by Hegelmaier I find the stipe scar con- 
stantly as in W. oblonga, while in diminutive forms of 
W. lingulata I find the position of the stipe scar constantly 
the same as in the larger more normal form. 
Specimens examined from California (S. B. and W. F. Parish, no. 
1100, in part, 1881, San Bernardino Valley). 
** Tongue-shaped; stipe insertion on the margin of the lower wall 
of the pouch. 
Wo.rrteLta Lineutata Hglm. Engler’s bot. Jahrb. 21°: 
303. Jan. 1895. Wolfia lingulata Hglm. Monogr. 
Lemnac. 132. May 1868.—Thompson, Ligulate 
Wolffias of the United States. Rept. Mo. Bot. Gard. 
7: 101-111. pl. 64-66. 26 May 1896. 
Fronds at maturity solitary or rarely in twos; ovate 
to oblong tongue-shaped; slightly unsymmetrical; 1.7-3 
mm. broad by 2.7-6.6 mm. long, about 1.5-3.5 times 
as long as broad; membranaceous; cavernous throughout 
the lower central portion; only a small part of the frond, 
above the base, exposed to the air; lateral margins up- 
turned along the middle portion, immature fronds fre- 
quently flat. Reproductive pouch usually equilaterally 
triangular, sometimes an isosceles triangle with the base 
a little narrower or broader than the sides. Stipe scar 
evident, on the margin of the lower wall of the pouch, to 
the right of the median line, slightly raised, truncate.— 
A Mexican species which at present time is reported from 
but one locality in our range. These specimens were 
collected by my brother and myself in the irrigation 
canals of Kern County, California, in 1895-96, nos. 201, 
204, 209.— Plate 4C. 
Wolffia Horkel ex Schleiden, Linnaea. 13: 389. 1839. 
Stipe attached under the solitary reproductive pouch and 
but a few cells from the margin. Fronds small, thick, 
19 
