Latin name

Eichhornia crassipes (Mart.) Solms-Laub.

Family

Pontederiaceae

Common name(s)

Water hyacinth

Synonym(s)

Eichhornia speciosa Kunth, Heteranthera formosa Miq., Piaropus crassipes (Mart.) Raf., P. mesomelas Raf., Pontederia azurea Sw., P. crassipes Mart., P. elongata Balf.

Geographical distribution

Asia: Japan.

South and Southeast Asia: Bangladesh, Cambodia, India, Indonesia, Lao PDR, Malaysia, Nepal, Philippines, Sri Lanka, Thailand, and Vietnam.

Rest of the world: Argentina, Australia, Bolivia, Brazil, Colombia, Costa Rica, Ecuador, El Salvador, Fiji, France, Germany, Guatemala, Honduras, Madagascar, Mexico, Nicaragua, Panama, Paraguay, Peru, Republic of Congo, Senegal, Sudan, Tanzania, Uganda, and United States.

Morphology

Floating or sometimes rooting in the mud, perennial herb up to 50—cm—high.

Stem: very short, rhizomatous or stoloniferous and rooting from nodes.

Leaf: spongy petioles up to 30—cm—long; blades broadly ovate or rhomboid, 8—15—cm—long.

Inflorescence: dense spike with long peduncle; 3—35 flowers, violet to blue.

Fruit: Three-celled capsule up to 1.2—cm—long; contains numerous minute seeds.

Seed: ovoid and ribbed, 0.5—1.0—mm—long.

Biology and ecology

Grows in canals, drains, rivers, swamps, lakes, and lowland rice.

Propagates by seeds and vegetatively with daughter plants developing from stolons that arise from axillary buds. Vegetative reproduction leads to large populations of the weed.

Plants growing from seed, emerge after 3 days, and after 1 month are at 7—8 leaf stage. First three leaves are spatulate and become "floats" after about 1 month growth.

Agricultural importance

Considered one of the "world's worst weeds" as it impedes the flow of water in irrigation canals, chokes lakes and reservoirs, and occasionally infests lowland rice fields.

Management

Cultural control: removal of the weed by hand or land-based machinery can be done where infestations occur in relatively narrow rivers. In lakes or larger water bodies, the weed can be pushed to the shore or harvested with floating machinery.

Biological control: by weevils Neochitina eichhorniae and N. bruchi.

Chemical control: Glyphosate or 2,4-D applied during rapid growth stages of the plant can be effective.

Selected references

Backer CA. 1951. Pontederiaceae. Flora Malesiana. Ser. 1 4:255-261.

Findlay JBR, Jones D. 1996. The integrated control of water hyacinth, Eichhornia crassipes, in Africa based on Roundup R herbicide treatments. In: Moran VC, Hoffmann JH, editors. Proceedings of the 9th international symposium on biological control of weeds, Stellenbosch, South Africa, 19-26 January 1996. p. 435-440.

Gutierrez E, Huerto R, Saldana P, Arreguin F. 1996. Strategies for water hyacinth (Eichhornia crassipes) control in Mexico. In: Caffrey JM, Barrett PRF, Murphy KJ, Wade PM, editors. Management and ecology of freshwater plants. Proceedings of the 9th International Symposium on Aquatic Weeds. European Weed Research Society, Dublin, Irish Republic, 1994. Hydrobiologia 340:1-3, 181-185.

Holm LG, Plucknett DL, Pancho JV, Herberger JP. 1977. The world's worst weed: distribution and biology. Honolulu, Hawaii (USA): University Press of Hawaii. 609 p.

Labrada R. 1996. Status of water hyacinth in developing countries. In: Strategies for water hyacinth control. FAO, Rome. p 3-14.

Moody K. 1989. Weeds reported in rice in South and Southeast Asia. Manila (Philippines): International Rice Research Institute. 442 p.

Contributors

JLA Catindig, RT Lubigan, and DE Johnson