Alien Invader Plants
Izihlahla Zokufika Ezhlaselayo
Uitheemse Probleem Plante

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CONTROL: 
Manual: Mechanical or hand removal is the most practical and preferred method.
Chemical: Chemicals are available for safe control, but are suitable mainly for maintenance work or small patches.
Biocontrol: Limited success because water hyacinth can grow into a large plant and the bioagents in use at present do not cause enough damage.

DESCRIPTION: Aquatic plants free floating or anchored when in shallow waters; shiny leaves with distinct swollen bladder-like stalks; mauve flowers produced in upright spikes; up to 10 flowers per spike.  A mass of fibrous roots hangs below the plant.  Flowering time: November to February.

ORIGIN: Originates from South America. Introduced into South Africa as an ornamental plant shortly after 1900.

WHERE FOUND/PROBLEMS CAUSED: Most troublesome in nutrient enriched waters and in situations of reduced flow e.g. in dams, weirs and certain rivers.  Affects water flow and light penetration; a permanent expense of on-going control in storage dams and water bodies used for recreation; may also increase loss of water to the atmosphere.

DID YOU KNOW: Water hyacinth is considered the world's worst waterweed.  Each flower spike can produce up to 5000 very fine seeds, which can remain dormant for 10-15 years.  The dying flower-stalks bend under the water to release the seeds.  It also has an amazing capacity for vegetative reproduction when daughter plants develop on side shoots and become detached.  Under optimal conditions in summer, water hyacinth colonies can double every 11-18 days.

This page was last edited on 23 April, 2006