Free Floating Plants  

Species: Eichhornia crassipes (Mart.) Solms, water hyacinth
Family: Pontederiaceae

Water hyacinth is a free-floating introduced plant with stalks of showy blue-violet flowers. The plants may vary from a few centimeters to over a meter tall. The broad leathery leaves are held above the water by swollen, spongy leaf bases which surround the stem to form a float. Fibrous roots dangle in the water from the underside of the plant. This popular water-garden plant is a severe pest in warm climates. Water hyacinth does not appear to be a problem in Washington because it seems unable to survive during our cool dark winters.

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Leaf: The glossy green, ovate to round leaves have parallel veins and smooth margins. They are up to 20 cm long and 15 cm wide. The leaf stalks have a spongy inflated base.

Stem:  Stout, short stems are often connected by stolons.

Flower: Showy flowers occur on 5 to 15 cm long spikes; each bearing 3-35 flowers. Individual flowers (to 7 cm across) have six bluish-purple petals joined at the base to form a short tube; one petal bears a yellow spot. There are 6 stamens, 3 of which may be hidden in the tube.

Fruit: Three-celled capsules have many tiny seeds.

Root: Long, fibrous, branched rootstocks hang from the underside of the plant.

Propagation: Prolific reproduction occurs from the vegetative formation of daughter plants which sprout from stolons. The seeds may germinate after being dormant for 15-20 years.

Importance of plant: Water hyacinth is considered to be the most problematic aquatic plant in warm latitudes. It should never be introduced to lakes or rivers.

Distribution: Native to South America, now abundant in many tropical and subtropical parts of the world.

Habitat:  Nutrient rich waters in warm climates. In the Pacific Northwest, it is planted outdoors in pools and in aquaria, but is not considered winter hardy.

May be confused with: The distinctive showy flowers and spongy leafInvasive Nonnative Plant Icon bases differentiates this from other northwest aquatic plants. Other water-garden plants like water lettuce (Pistia stratiotes) or pickerelweed (Pontederia cordata) may initially look similar.

Photographs: Closeup of Eichhornia crassipes flower, field of water hyacinths

Line Drawings: Eichornia crassipes

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