Water hyacinth
Botanical Name
Pontederia crassipes
Family
Pontederiaceae (pickerel-weed)
Where is it originally from?
South America
What does it look like?
Free-floating aquatic perennial. Distinctive swollen, bladder-like petioles attached to heavy, glossy, leathery leaves allow it to float on the surface of water. Pale lilac hyacinth-like flowers with purple markings and a yellow spot inside emerge above foliage.
Why is it weedy?
Spreads rapidly - twenty five plants can form a one hectare mat over one growing season. Frost-tender, but dense mats can tolerate moderate frosts.
How does it spread?
Seeds and plant fragments are dispersed by water, wind, machinery. Seeds remain viable for up to 20 years.
What damage does it do?
Grows rapidly, forms dense mats on the surface of them, choking them and displacing native plants.
Which habitats is it likely to invade?
Still or slow moving freshwater - ponds, streams, swamps.
What can I do to get rid of it?
If you suspect that you have found water hyacinth, do not touch it. This pest plant is under an active national eradication programme, and any attempt to get rid of it could accidentally spread the pest. Any plants found that are suspected to be this species should be reported to Biosecurity New Zealand using the pests-and-diseases hotline on 0800 80 99 66. They will work with you to control the weed.
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