Giant duckweed
Spirodela polyrhiza · Aquatic plants
A stand of it · Photo: Petr Harant / CC BY
Also called Big duckweed, Spirodela polyrrhiza, Greater duckweed, Water flaxseed
How to identify Giant duckweed
- Round fronds 1/4 to 3/8 inch, the largest duckweed
- Underside purple to reddish
- Several roots per frond, 5 to 15
- Forms small dark winter buds that sink in fall
Similar plants
Common duckweed is smaller, green underneath and has one root, and dotted duckweed is smaller with 2 to 7 roots and purple dots.
Growth profile
| Growing season | Winter buds rise in late spring, fronds peak from July to September, and new buds sink to the bottom in fall. |
|---|---|
| Starts growing | About 55 to 60 F water |
| Light | Full sun to partial shade |
| Depth | Surface of still water of any depth |
| How it spreads | Budding fronds and winter buds |
| Habitat | Quiet, warm, nutrient rich ponds and ditches. |
Why it matters in a lake
Often mixed with common duckweed and watermeal in full surface mats. Winter buds on the bottom restart the population each year.
Where it is found
- Idaho: Occasional
- Oregon: Common
- Wyoming: Occasional
Classification
| Kingdom | Plantae |
|---|---|
| Phylum | Tracheophyta |
| Class | Magnoliopsida |
| Order | Alismatales |
| Family | Araceae |
| Scientific name | Spirodela polyrhiza |
Common duckweed
Columbia watermeal
Mosquito fern
Star duckweed
Purple fringed riccia
Turion duckweed
Mexican mosquito fern
Least duckweed
Floating crystalwort
Brazilian watermealNeed a hand?
Is it taking over your lake?
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