Many people in Louisiana are surprised to learn that water
hyacinths are not native plants because they are found throughout the
state in bayous, lakes and even drainage ditches. This floating, flowering
plant from South America was introduced into Florida in the 1890s, and
into Louisiana around 1903 at the Cotton Exposition in New Orleans.
Today, it is considered an invasive species throughout the South by
some, although also valued as one of the top-selling plants for the
water garden industry.
This plant forms a dense floating carpet on ponds, lakes
and bayous that blocks sunlight. Lack of sunlight often kills
submerged plants and results in low oxygen levels in the water. In addition,
as leaves drop off and decay, more sediment falls to the waterway's
bottom, increasing sedimentation rates in the waterway.
The plant has dark green, waxy, rounded and cupped leaves
attached to a bulb-shaped petiole. Seasonally, a spike of lavender flowers
at the end of a stem is produced. Each floating plant has dense, fibrous,
branching roots that may extend for 2-3 feet beneath each plant, and
a rhizome to start a new plant. Plants can vary in size from a few inches
to more than 3 feet tall. In Louisiana, they are rarely more than 12
inches.
