28 ADDISONIA 
America. The plants grow partly submersed in water, on moist 
or muddy shores, or on sandy flats. 
Although varying greatly in size, the most conspicuous variation 
is in the leaf-blades. These range from very inconspicuous organs 
with narrowly linear lobes to conspicuous objects with deltoid 
lobes, the whole blade sometimes assuming a deltoid-reniform 
outline. Plants with these large leaves often take complete pos- 
session of swamps, covering extensive areas with their leaves, 
overtopped during the flowering season by the panicles of white 
owers. 
For many years our plant was confused with one of similar habit 
native in Europe. In the first decade of the last century the 
American plant was definitely separated from the other. Then 
for about a century this plant was renamed many times, chiefly 
on account of the great variability in the form of the leaf-blades. 
This type of variability is very common in many aquatic plants, 
and it is now understood that these various forms represent only a 
single species. 
The starchy tubers of the arrow-head were formerly extensively 
used by the North American Indians for food. ‘The plant has 
been exterminated in many places, both by the advance of civil- 
ization and by the introduction into ponds, lakes, and streams of 
certain fish that live largely on the young plants of this and other 
aquatics, 
Joun K. SMALL. 
EXPLANATION OF PLATE, Fig. 1—Part of a leaf, showing upper portion of 
the petiole and the blade. Fig. 2.—Inflorescence. Fig. 3.—A whorl of fruit- 
heads. Fig. 4.—An achene, X 5. 
