The water hyacinth is a pretty but pesky aquatic weed that floats in warm, peaceful ponds in the low hills around the San Fernando Valley. It is also prevalent along the Tujunga Wash near Hansen Dam in Sunland.
Purple flowers, which bloom in summer and autumn, crown a spongy mass of green leaves that bob on the water's surface. The upper petal of each flower is marked with a conspicuous peacock tail of blue stripes fanning out from a spot of bright gold.
Buoyant petioles spread out beneath kidney-shaped leaves at the plant's base, and black roots trail into the water to prevent the hyacinth from capsizing.
The water hyacinth ( Eichhornia crassipes) can grow as tall as three feet, especially in the humidity of the Gulf Coast. The plant originated in South America, and it flourishes in humid climates. Southern bayous often are covered by its purple and green between April and October.
The water hyacinth propagates rapidly--three plants can grow to 3,000 within 50 days--by runners detaching themselves from the parent plant. The plants, if left unchecked, choke small ponds and medium-size lakes with flowers and dangling roots.
The growth provides a refuge for frogs and fish. But because the hyacinth has no practical uses and clogs waterways, some states spend millions of dollars each year to control the pretty pest.