Water chestnut
Trapa natans · Aquatic plants
Whole plant · Photo: Milan Chytrý / CC BY
Also called Trapa, Water caltrop, European water chestnut
State noxious weed listing
- Idaho: Early detection
- Oregon: A list
How to identify Water chestnut
- Floating rosettes of triangular toothed leaves
- Leaf stalks with swollen spongy air bladders
- Hard black nuts with 4 sharp spines
- Long rooted stem anchors the rosette
Similar plants
Water smartweed has oblong leaves and pink flowers, and floating leaf pondweeds lack toothed triangular leaves.
Growth profile
| Growing season | Seeds sprout in spring, rosettes cover the surface by midsummer, nuts ripen in late summer, and plants die in fall leaving nuts on the bottom. |
|---|---|
| Starts growing | About 54 F water for seeds to sprout |
| Light | Needs full sun |
| Depth | 1 to 15 feet |
| How it spreads | Spiny nuts, which stay viable for up to 12 years |
| Habitat | Quiet, nutrient rich ponds, lake bays and slow rivers over soft mud. |
Why it matters in a lake
Forms dense mats that block boating and swimming, and the spiny nuts can injure feet. It is on the Idaho early detection list and listed in Oregon.
Where it is found
- Idaho: Not yet found
- Oregon: Not yet found
- Wyoming: Not recorded
Classification
| Kingdom | Plantae |
|---|---|
| Phylum | Tracheophyta |
| Class | Magnoliopsida |
| Order | Myrtales |
| Family | Lythraceae |
| Scientific name | Trapa natans |
American pondweed
Floating leaf pondweed
Yellow pond lily
Fragrant water lily
Water smartweed
Floating marshpennywort
Uruguay water primrose
Watershield
Water purslane
Floating primrose willowNeed a hand?
Is it taking over your lake?
We identify what is growing, map how much of it there is and build a control plan that targets it without harming the rest of the lake.
Idaho / Wyoming (208) 501-4531Oregon (541) 280-0596