LIGULATE WOLFFIAS OF THE UNITED STATES. Ill 
the Wolffia was an abundance of Lemna Valdiviana min- 
ima^ Hegelm., and a lesser quantity of Lemna minor L. 
The figures were drawn by Miss Grace E. Johnson from 
sketches prepared by the author. 
Plate 64. Woljffia gladiata Floridana J. D. S.— I, 2, 3, 4, 5, Matnre 
base of frond showing the pocket wi 
6 ; 8, a portion of the upper epidermis 
tion of transverse section of frond showing epidermal layers, partition 
walls and air cavities, X 125; 8, portion of epidermal tissue showing two 
pigment cells, X 320; 9, stipe scar and end of costa, X "5; 10, epidermal 
cells showing general form and relatively smaller pigment cells. Beneath 
are shown chains of cells forming walls of air cavities — chlorophyl 
grains drawn in these to better bring out these partition cells, X 200 ; 11, 
Plate 66, Wolffia lingulata Hegelm,— 1, Plant showing offspring in 
various stages of development and their respective positions, under 
surface, X 8 ; 2, longitudinal section of plant through the reproductive 
pouch showing position of offspring from a lateral view, X 16 ; 3, 4, 5, 6, 
a series of longitudinal sections through the reproductive pouch like 
