292 
FLORIDA GEOLOGICAL SURVEY—THIRD ANNUAL REPORT. 
WATER-HYACINTH PEAT. 
The water hyacinth, Piaropus (formerly Eichkornia j once 
Pontederia ) crassipcs, a beautiful ornamental aquatic plant, 
native of South America, began to escape from cultivation and 
make itself a nuisance in Florida about twenty years ago. It 
thrives in our lakes and estuaries probably almost as well as in its 
native haunts, and for a time it threatened to close the St. Johns 
River to navigation.* For some reason not altogether obvious, 
it is much less troublesome now than formerly, having apparently 
reached a state of equilibrium. It has some redeeming features, 
too. It is undeniably a beautiful plant when in bffiom, cows like 
to eat it, and finally, it may be an important source of peat. 
For it grows pretty rapidly, and in just the places which are 
best adapted for the formation of peat. It is never found in salt 
or swift water, in ponds which dry up completely, or in streams 
subject to great fluctuations; and not often in muddy or calcareous 
water. Its favorite habitat is permanent ponds, lakes and estuaries, 
sometimes floating on the water, and sometimes taking root on 
mucky or peaty shores, but in either case constantly decaying and 
producing peat. 
The Withlacoochee River near Istachatta, at the northeastern 
corner of Hernando County, (and doubtless elsewhere) was in 
January, 1909, completely covered from shore to shore with a dense 
mass of water hyacinth, and I was told that a man could take a 
couple of planks of sufficient size and with their aid walk across 
the river on the plants. In the edge of the river I noticed some 
logs partly submerged, which could not have been there many years, 
and on top of them 1 a few inches of peat, evidently formed mostly 
from the hyacinths. Associated with the water hyacinth in this 
river, and partly supported by it, I noticed Decodon verticillatus, 
a weak herb-Jike shrub, and the following aquatic herbs. 
*An interesting account of its status in Florida, written by Dr. H. J. Webber 
about the time it was at its worst, can be found in Bulletin 18 of the Division 
of Botany, U. S. Department of Agriculture, published in 1897. 
At various times in the last ten years the U. S. Army engineers have con¬ 
ducted experiments in Florida, mostly on the St. Johns River, with a view to 
exterminating the water hyacinth, sometimes by mechanical and sometimes by 
chemical means. (See Reports of the Chief of Engineers, 1899: 276-277, 
1612-1613; 190: 315, 1985; 1901: 1746-1749; 1903: 1184-1186; 1904: 
1712-1713; 1905: 1318; 1906: 330-331, 1234-1239; especially the last.) Spraying 
with poisonous liquids was found to be most effective, but had the serious draw¬ 
back of poisoning cattle which fed on the plants. 
