Water hyacinth

Scientific

Pontederia crassipes (recently renamed from Eichhornia crassipes) — family Pontederiaceae. The plant is free-floating, with swollen petioles filled with spongy aerenchyma tissue that provides buoyancy. Roots dangle in the water column rather than anchoring in substrate.

Reproduction is by both seed (long-lived in sediment) and vegetative offshoots — daughter plants split off from parent rosettes. Under optimal conditions a population can double in size every 6–18 days, producing the explosive surface-coverage that defines the species’ invasive impact.

Invasive ecological impact

Water hyacinth is one of the most damaging invasive species on Earth. Native to the Amazon basin, the species was introduced to many tropical and subtropical regions in the late 19th and 20th centuries as an ornamental for ponds and water gardens. From those introductions it has escaped to become a major invader of major water bodies in:

• Lake Victoria, East Africa — the species peaked at ~12% surface coverage in the late 1990s, devastating the fishery industry that supports 30+ million people
• Kerala backwaters, India — extensive coverage of the canal system; impacts on tourism, fishing, transportation
• The Nile River — coverage in Sudan and Egypt
• The Niger and other West African rivers
• Florida and [[arabi|Louisiana]] waterways — the introduction route into the US was the 1884 [[french-quarter|New Orleans]] Cotton Exposition

The ecological mechanisms of damage:

• Dense mats block sunlight from submerged plants; aquatic plant communities collapse
• Decomposing mats deplete dissolved oxygen; fish kills are common
• Mats prevent navigation, fishing, and water-pump intake
• Provides breeding habitat for malaria-vector mosquitoes
• Evaporative water loss from covered water bodies can be 3–5x higher than open water

Control efforts

The 2000s biological control of Lake Victoria — releasing weevils that specifically eat water hyacinth — reduced coverage substantially and is one of the largest successful biological-control programs ever attempted. Mechanical harvesting, herbicidal control, and harvesting for biogas / compost / fiber are all attempted at various scales in different affected regions.

The plant is also being actively explored as a phytoremediation species — it absorbs heavy metals and excess nutrients from polluted water at remarkable rates, making “managed water hyacinth” a tool for sewage treatment in some regions even as the species causes catastrophic damage in others.

See also

Auto-generated from this entry’s typed relations: frontmatter, grouped by relation type so the editorial signal isn’t flattened.

• Shares approach with: [[wineberry]] · [[water-lily]] · [[wapato]] · [[tree-of-heaven]] · [[sacred-lotus]] · [[rubber-tree]]
• Member of: [[plants]]

Sources

• Wikipedia — Water hyacinth
• Global Invasive Species Database

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A plant entry in the 0mn1.one [[directory]].