common water hyacinth (Pontederia crassipes) — identification, habitat & look-alikes

Common water hyacinth is a South American floating plant that has become invasive in warm parts of the United States. Its swollen leaf stalks keep it afloat, and it has glossy leaves and lavender flower spikes. Dense growth can block waterways, shade underwater plants, and lower oxygen levels in the water.

Appearance

Growth form: This perennial floats freely, with dark feathery roots hanging in the water and connected plants forming .
Leaves: The smooth, glossy leaves are round to oval. Swollen leaf stalks act as floats, although crowded plants may develop longer, less swollen stalks.
Flowers: Lavender flowers grow together on an upright spike, usually with a darker blue-purple and yellow mark on the upper flower segment.

Look-alikes

anchored water hyacinthPontederia azurea

Anchored water hyacinth has long floating stems and narrow leaf stalks that never swell like the floats on common water hyacinth. It is rooted in shallow water, while common water hyacinth floats freely.

Why they get mixed upBoth have upright leaves and similar blue-purple flowers in Florida waterways.

Where it lives

Typical habitats: ponds
lakes and reservoirs
slow rivers and canals
Range: Established populations persist across the southeastern United States from North Carolina to Texas and in parts of the Southwest, including California and Arizona. Plants found farther north often fail to survive winter.
Preferred conditions: It grows fastest in warm, sunny, nutrient-rich, slow-moving fresh water.

Life cycle

Reproduction: Plants spread quickly by that produce daughter plants. They can also reproduce by seed.

Growing it

Propagation: Loose plants and daughter plants can drift with water or wind and begin new patches.

Name and classification

About the name: Common water hyacinth was formerly called Eichhornia crassipes.

Conservation

IUCN Red List: NENot EvaluatedNot yet assessed
Threats: Thick growth can block navigation and drainage, shade submerged plants, and contribute to low oxygen in the water.

Culture and stories

Culture and stories: It has long been sold as an ornamental for fish ponds and water gardens.
Plants released or discarded from ponds can escape into lakes, reservoirs, and rivers.
Florida lists it as a noxious weed and a prohibited aquatic plant.

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