Hydrilla
Hydrilla verticillata
Center for Aquatic Plants
|
HydrillaHydrilla verticillata |
| University of Florida, IFAS, Center for Aquatic Plants |
Invasive Nonindigenous Plants in Florida |
is an
invisible menace, invisible that is until it fills the lake or river that it infests. When hydrilla
invades,
ecologically-important native submersed plants such as tapegrass and coontail are shaded out and
eliminated; recreational and even commercial boating becomes difficult; swimming becomes
unpleasant and even dangerous; fishing becomes impossible... Millions of dollars are spent each
year on herbicides and mechanical harvesters in Florida in an effort to place hydrilla under
"maintenance control". Managing hydrilla using biological
control insects also is part of the management mix used in Florida. Hydrilla is the
"number 1" aquatic weed problem in the state.
Hydrilla (Hydrilla verticillata)
Hydrilla can grow an inch a day! It was first found in Florida in the 1960s,
probably accidentally introduced by an aquarium-enthusiast. In thirty years, hydrilla has
spread throughout Florida, and is now found in about a dozen other states as far north as
Connecticut, as far west as California. It is on the Florida and the federal "prohibited plant" lists. (See hydrilla distribution
maps on the U.S.
Geological Survey web site.)
Hydrilla can grow in almost any freshwater: springs, lakes, marshes, ditches, rivers, tidal zones. It can grow in only a few inches of water, or in water 20 feet deep.
Hydrilla is a long, sinewy, underwater plant. Its branching stems can grow to 25 feet long. Hydrilla's small
leaves are strap-like and pointed. The leaves grow in
whorls of 4 to 8 around the stem. The leaf
margins are distinctly saw-toothed. Hydrilla
often
has one or more sharp teeth along the length of
the leaf mid-rib. Hydrilla produces tiny
white flowers on long stalks. It also produces 1/4-inch long turions at the leaf axils and potato-like tubers attached to the roots in the mud. New plants grow from
the turions and tubers.
For more information and pictures about hydrilla, as contained in the
Langeland/Burks book, Identification & Biology of Non-Native Plants in Florida's Natural
Areas, download this Acrobat .PDF file.
Here is additional basic information about the
identification, biology, physiology, importance and management of hydrilla.
