• water hyacinth is a floating, flowering perennial
• floating, "obligate" (requiring a wet habitat)
• linked plants form dense rafts in the water and mud
• will halt boat traffic on rivers; will cover a lake surface from shore to shore

Habitat:

• an aquatic weed worldwide; in lakes, rivers, ponds, ditches of temperate climates
• temperature tolerance: water hyacinth is not winter-hardy; its minimum growth temperature is 12^o C (54^o F); its optimum growth temperature is 25-30^o C (77-86^o F); its maximum growth temperature is 33-35^o C (92-95^o F) (Kasselmann 1995)

Quick ID:

Eichhornia crassipes: when flowering, water hyacinth is very easy to identify; a floating plant with thick, glossy, round leaves, inflated leaf stems, and very showy lavender flowers; sometimes found stuck in mud, appearing rooted; it is rarely found singly


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Eichhornia crassipes (Mart.) Solms

Original description:



• monocot, perennial
• free-floating, except when stranded in the mud; mother plants and daughter plants attached by floating stolons
• leaves formed in rosettes rise to three feet above the water; leaves entire, ovate, rounded, circular, or broadly elliptic, to 6 in. wide; thick, glossy, waxy green, waterproof; sides gently incurved and often undulate; leaf base hearshaped, squared or rounded; veins dense, numerous, fine, longitudinal
• petioles (leaf stems) floating, creeping; inflated, bulbous, spongy, to 12 in. long
• multiple (8 to 15) flowers in a single very showy, spike (spathe) to 12 in. long; spike at top of erect thick stalk to 20 in. long, rising above the leaves; each flower in the flower-spike with six lavender-blue petals (perianths), petal tips slightly 2-lipped; uppermost petal somewhat larger, lavender, having a bright yellow, blue-bordered central oval splotch; stamens 6, stigmas 3
• roots hanging submersed beneath floating leaves, dark purplish to black, feathery, tips with long root caps
• fruit a capsule, 3-celled, with many seeds; seeds ribbed, formed in submerged, withered flower; fruit and seeds are rarely observed; seeds may produce many seedlings in moderate climates

• native frog's-bit (Limnobium spongia), a common native plant also having shiny round(ed) leaves:
  --water hyacinth leaf stems (petioles) are inflated and spongy; frog's-bit leaf stems are thin and firm
  --water hyacinth roots are dark purplish-black and full; frog's-bit roots are whitish and relatively sparse
  

  Here is more information and pictures for the native plant, frog's bit.

• Water hyacinth is present in the states of the southeast U.S., and California, Hawaii, and the Virgin Islands. The occurrences in Arizona, Arkansas and Washington, shown in the map above left, are now believed to be "eradicated".
• According to the U.S.G.S., water hyacinth has been reported in New York, Kentucky, Tennessee and Missouri "where plants escape summertime cultivation but do not persist through the winter...it is annually stocked in farm fish ponds in southern Arizona and southern Delaware," but has not become established in the natural systems of these states.

  

  U.S. Drainage Distribution Map, occurrences, and other information about Eichhornia crassipes was prepared by C. Jacono of the U.S. Geological Survey, Nonindigenous Aquatic Species Program, which is located on the USGS-NAS web site.
  

  The best way to track the spread of invasive aquatic plants may be to identify the drainage basins (watersheds) they have been discovered in. Drainage maps give useful information to eco-managers because drainage maps show precisely where the plants are, making it easier for managers to infer where the plants might go next, and thus where to take preventive measures.
  

Problems/Effects:

• Eichhornia crassipes mats clog waterways, making boating, fishing and almost all other water activities, impossible
• water flow through water hyacinth mats is greatly diminshed
• an acre of water hyacinth can weigh more than 200 tons; infestations can be many, many acres in size; mats may double their size in as little as 6-18 days (Mitchell 1976);
• water hyacinth mats degrade water quality by blocking the air-water interface and greatly reducing oxygen levels in the water, eliminating underwater animals such as fish (Penfound & Earle 1948)
• water hyacinth greatly reduces biological diversity: mats eliminate native submersed plants by blocking sunlight, alter emersed plant communities by pushing away and crushing them, and also alter animal communities by blocking access to the water and/or eliminating plants the animals depend on for shelter and nesting (Gowanloch 1944)
• in Florida, millions of dollars a year used to spent on water hyacinth control; finally getting the plant under "maintenance control" has greatly reduced that expenditure

Due to decades of university, state and federal research and experience with Eichhornia crassipes in the U.S., several methods have been developed to help in its management:

the action of mechanical harvestors and chopping machines remove water hyacinth from the water and transport it to disposal on shore; chopping machines grind the plant into bits and spray the slurry across the water


years of research to find insect biocontrols has resulted in the successful introduction of two water hyacinth weevils, which are believed to be keeping water hyacinth under maintenance control in many places; however biocontrol fish which are able to control submersed plants are ineffective against the floating water hyacinth

registered aquatic herbicides do provide temporary control of water hyacinth

From the University of Florida Aquatic Weed Management Guide by V.V. Vandiver, 1999:


According to this Guide, ... As always, comply with federal law by following the herbicide label instructions, permissible sites and application rates.

First, clean your boat before you leave the ramp! Transporting plant fragments on boats, trailers, and in livewells is the main introduction route to new lakes and rivers.
But, there's plenty more you can do to help.

The information contained on this wep page was extracted from published scientific literature and agency reports. It is important to know that plant research, like most areas of scientific research, is still relatively young and incomplete--much may have been published about the physiology of one plant but not about its management; much may have been published about how to culture and grow another plant but not about its natural ecology. Thousands of research articles may have been published about one invasive plant, but perhaps only a dozen about another.

If you want to read the research yourself, perhaps to clarify or expand an area of information contained here, or to help determine your own line of research, you are welcome to query the world's largest collection of international scientific literature about aquatic, wetland and invasive plants, the APIRS bibliographic database, which contains more than 54,000 citations and their content keywords. Or you might want to ask us to do it for you and mail or e-mail the search results to you.

This is the literature about Eichhornia crassipes that was used to develop this web page. More research items about this plant may be found at APIRS:

• Gowanloch JN. 1944. The econimc status of water-hyacinth in Louisiana. La. Conserv. 2:3-8
• Holm LG, Plucknett DL, Pancho JV, Herberger JP. 1977. The world's worst weeds: distribution and biology. Honolulu: University Press of Hawaii. 609 pp.
• Kasselmann C. 1995. Aquarienpflanzen. Egen Ulmer GMBH & Co., Stuttgart. 472 pp. (In German)
• McCann JA et al. 1996. Nonindigenous aquatic and selected terrestrial species of Florida-Status, pathway, and time of introduction, present distribution, and significant ecological and economic effects. Southeastern Biological Science Center, Gainesville, 256 pp.
• Mitchell DS. 1976. The growth and management of Eichhornia crassipes and Salvinia spp. in their native environment and in alien sitautions. In: Varshney CK, Rzoska J, editors, Aquatic weeds in Southeast Asia. The Hague: Dr. W. Junk b.v., Publishers. 396 pp.
• Penfound WT, Earle TT. 1948. The biology of the water hyacinth. Ecol. Monogr. 18:449-72.
• Schmitz DC, Schardt JD, Leslie AG, Dray FA, Osborne JA, Nelson BV. 1993. The ecological impact and management history of three invasive alien aquatic plants in Florida. In: McKnight BN, editor, Biological pollution - the control and impact of invasive exotic species. Indianapolis: Indiana Acad. Science. 261 pp.
• Van TK, Steward KK. 1982. Evaluation of chemicals for aquatic plant control. Annual Report 1981, Ft. Lauderdale, FL, 66 pp.
• Vandiver VV. 1999. Florida aquatic weed management guide. Univ. of FL, IFAS, Cooperative Extension Service, Publ. SP-55, 130 pp.
• Wolverton BC, McDonald RC. 1979. Water hyacinth (Eichhornia crassipes) productivity and harvesting studies. Econ. Botany 33:1-10.

Water hyacinth chapter from Langeland/Burks book,

Identification & Biology of Non-Native Plants
In Florida's Natural Areas


Here is an article on using water hyacinth to make things in Kenya.