Water Velvet Azolla caroliniana
Other Common Name(s):
- Phonetic Spelling
- a-ZOL-luh kair-oh-lin-ee-AN-uh
- Description
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Eastern mosquito fern is a native annual aquatic plant in the Water-fern family (Salviniaceae). It is widespread in eastern North American and northern South America, growing in still or very slow-moving water, shallow ponds, ditches and sluggish streams.
It grows in partial to full sun, in permanent standing water. To propagate this plant, move divisions of it to a new area. To keep it alive when temperatures dip, overwinter it indoors.
The delicate, lacey, scale-like leaves overlap and float on the water’s surface forming a dense mat with the roots trailing below the surface. New leaves are a bright green or gray green and can fade to rusty red especially if grown in bright conditions. The leaflets house a symbiotic blue-green alga (Anabaena azollae) that fixes nitrogen. This very short plant grows less than 1 inch tall but can break off and form a mat that covers the water’s surface very quickly making it difficult for mosquitos to deposit their eggs, hence the common name "mosquito fern." Another explanation is that this fern is associated with mosquitoes, as they both favor similar environments.
Use it in water gardens, ponds or aquaria. The leaves are normally not eaten by fish. It is a rapidly growing and spreading aquatic plant, which may affect the location chosen for its use.
Insects, Diseases, and Other Plant Problems: No serious problems.
- See this plant in the following landscape:
- Cultivars / Varieties:
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- Cultivars / Varieties:
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Attributes:
- Genus:
- Azolla
- Species:
- caroliniana
- Family:
- Salviniaceae
- Uses (Ethnobotany):
- Grown in rice paddies as a green fertilizer or used as animal feed. It is being studied as a biofuel and has been used for pollution mitigation.
- Life Cycle:
- Annual
- Recommended Propagation Strategy:
- Division
- Stem Cutting
- Country Or Region Of Origin:
- Americas
- Wildlife Value:
- This plant benefits waterfowl and shorebirds.
- Play Value:
- Wildlife Cover/Habitat
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Whole Plant Traits:
- Plant Type:
- Annual
- Fern
- Native Plant
- Water Plant
- Habit/Form:
- Spreading
- Growth Rate:
- Rapid
- Maintenance:
- Medium
- Texture:
- Fine
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Cultural Conditions:
- Light:
- Full sun (6 or more hours of direct sunlight a day)
- Partial Shade (Direct sunlight only part of the day, 2-6 hours)
- Soil Drainage:
- Frequent Standing Water
- Occasionally Wet
- Available Space To Plant:
- Less than 12 inches
- NC Region:
- Coastal
- Piedmont
- USDA Plant Hardiness Zone:
- 7a, 7b, 8a, 8b, 9a, 9b, 10a, 10b, 11a, 11b
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Fruit:
- Display/Harvest Time:
- Summer
- Fruit Description:
- No fruits. Magaspores (female gameophytes) and microspores (male gametophyte) appear from June to September.
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Flowers:
- Flower Description:
- No flowers.
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Leaves:
- Leaf Color:
- Gray/Silver
- Green
- Red/Burgundy
- Deciduous Leaf Fall Color:
- Red/Burgundy
- Leaf Type:
- Fronds
- Leaf Margin:
- Lobed
- Hairs Present:
- Yes
- Leaf Length:
- < 1 inch
- Leaf Width:
- < 1 inch
- Leaf Description:
- Lacey, bright green to gray green fronds arranged in two rows of .5 mm long scale-like leaves with two lobes. The upper leaf is above the surface and the lower larger leaf floats below. On the upper lobe leaves have one celled hairs. Turn reddish in full sun and during fall.
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Stem:
- Stem Is Aromatic:
- No
- Stem Description:
- Prostrate stems branch
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Landscape:
- Landscape Location:
- Pond
- Landscape Theme:
- Native Garden
- Water Garden
- Problems:
- Weedy