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Montana Field Guides

Common Water Hyacinth - Eichhornia crassipes
Other Names:  Common Water-hyacinth

Aquatic Invasive Species
Non-native Species
Not Documented

Global Rank: G5
State Rank: SNA
(see State Rank Reason below)

Agency Status


External Links

State Rank Reason (see State Rank above)
Eichhornia crassipes is not known to occur in Montana. A conservation status rank is not applicable (SNA) because the plant is not a suitable target for conservation activities. The purpose of this profile is to provide awareness and education to prevent its introduction into Montana. Preventing deliberate plantings and spread from plant fragments are the best means to keep this plant out of Montana’s waters.
General Description
PLANTS: Aquatic, perennial plants that are often free-floating or root in mud. Vegetative stems grow immersed or at the water’s surface, but while flowering stems grow at or above water. Source: Flora of North America [FNA] 2002.

LEAVES: Basal leaves are sessile (no petiole) in a rosette. Leaves with petioles float or are submersed with an ovate to round blade, 2.5-11 x 3.5-9.5 cm. Petioles are at least slightly swollen. Stipules are 2.5-14 cm with a truncate tip. Source: FNA 2002.

INFLORESCENCE: Blue or mauve-blue flowers arranged in a spike, 4-15 flowered, and on a stem that elongates over several days. Spathes are obovate, 4-11 cm. Peduncles are 5-12.5 cm and glabrous. Source: FNA 2002.

Flowering early spring to late fall (FNA 2002). Flowers open individually soon after sunrise and wilt by night (FNA 2002). By the next morning the flowering stem bends and developing fruits submerge and seeds develop under water(FNA 2002).

Range Comments
Common Water Hyacinth was likely introduced into the U.S. at the Louisiana Exposition in 1884 (FNA 2002). It is found in states where freezing temperatures are limited, including Alabama, Arizona, California, Florida, Georgia, Louisiana, Mississippi, North and South Carolina, Texas, and Virginia (FNA 2002). In Washington it is found as a garden escape, but rarely survives most winters (Giblin et al. [eds.] 2018).

For maps and other distributional information on non-native species see:
Nonindigenous Aquatic Species Database from the U.S. Geological Survey
Invasive Species Habitat Tool (INHABIT) from the U.S. Geological Survey
Invasive Species Compendium from the Centre for Agriculture and Bioscience International (CABI)
EDDMapS Species Information EDDMapS Species Information

Ponds, ditches, canals, and slow moving rivers (FNA 2002).
Predicted Suitable Habitat Model

This species has a Predicted Suitable Habitat Model available.

To learn how these Models were created see

Reproductive Characteristics
FLOWER and FRUIT [Adapted from FNA 2002]
Flowers have blue to mauve-blue fused sepals and petals (tepals), 16-37 mm. The tepals are fused into a funnel-shape with obovate lobes. The central lobe has a dark blotch with a yellow spot. Flowers have 6 stamens, 3 shorter (14-29 mm) and 3 longer (20-35 mm), with curved filaments and yellow anthers. The pistil has a 3-lobed style, 3-locular (incomplete) ovary, and many ovules.

Fruits are capsule-like and elongate. Seeds are 11- to 14-winged, 1-2 mm by 0.6-0.9 mm, and many.

Pesticide and biological control methods used in Florida may have resulted in declines (FNA 2002). Field Guide users in need of controlling this species should consult references listed by the author in FNA 2002 [eFloras]

Contact information for Aquatic Invasive Species personnel:
Montana Fish, Wildlife, and Parks Aquatic Invasive Species staff
Montana Department of Natural Resources and Conservation's Aquatic Invasive Species Grant Program
Montana Invasive Species Council (MISC)
Upper Columbia Conservation Commission (UC3)

Threats or Limiting Factors
Common Water Hyacinth may be the most aggressive aquatic weed ever known in the tropics (FNA 2002). It has been documented to cause extensive physiological changes in water bodies (FNA 2002).

  • Literature Cited AboveLegend:   View Online Publication
    • eFloras. No Date. Published on the Internet Missouri Botanical Garden Herbarium, St. Louis, Missouri and Harvard University Herbarium, Cambridge, Massachusetts
    • Flora of North America Editorial Committee. 2002. Flora of North America North of Mexico. Vol. 26. Magnoliophyta: Liliidae: Liliales and Orchidales. New York, NY: Oxford Univ. Press. xxvi + 723 pp.
    • Hitchcock, C.L. and A. Cronquist. 2018. Flora of the Pacific Northwest: An Illustrated Manual. Second Edition. Giblin, D.E., B.S. Legler, P.F. Zika, and R.G. Olmstead (eds). Seattle, WA: University of Washington Press in Association with Burke Museum of Natural History and Culture. 882 p.
  • Web Search Engines for Articles on "Common Water Hyacinth"
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Citation for data on this website:
Common Water Hyacinth — Eichhornia crassipes.  Montana Field Guide.  .  Retrieved on , from