LIGULATE WOLFFIAS OF THE UNITED STATES. FIL 
the Wolffia was an abundance of Lemna Valdiviana min- 
ima, Hegelm., and a lesser quantity of Lemna minor L. 
EXPLANATION OF PLATES ILLUSTRATING THE LIGULATE 
WOLFFIAS OF THE UNITED STATES. 
The figures were drawn by Miss Grace E. Johnson from 
sketches prepared by the author. 
Plate 64. Wolffia gladiata Floridana J. D. S.—1, 2, 8, 4,5, Mature 
plants with offspring, * 8; 5, three generations of fronds attached; 6, 
bases of a group of attached fronds showing the formation of so-called 
“families; ’’ 7, base of frond showing the pocket with two offspring 
attached to its matrix, the older of which also has a young individual in 
its pocket, < 36; 8,a portion of the upper epidermis next the margin 
showing epidermal cells with pigment cells, K 145; 9, a group 
(‘* family ’’) of plants, X 5. 
Plate 65. Wolffia lingulata Hegelm.—1, A frond just separated from 
its parent, x 8; 2, 3, 4, 5, frond showing variations in shape and line 
of direction in growth of young fronds, 8; 5, shows position and rela- 
tive size of air cavities; 6, normal position of fronds in water, x 5; 7, por- 
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, 75; 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, 200; 11, 
portion of costa about midway between stipe-scar and basal angle of 
pouch, X 75. 
Plate 66, Wolfia lingulata Hegelm.—1, Plant showing offspring in 
various stages of development and their respective positions, under 
surface, < 8; 2, longitudinal section of plant through the reproductive 
pouch showing position of offspring from a lateral view, 16; 3, 4, 5, 6, 
a series of longitudinal sections through the reproductive pouch like 
last but more enlarged, X 125; 7, 8, 9, diagrams representing the posi- 
tion of stipe and costa, also transition of prismatic cells,— under surface 
of frond, < 8. 
