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Egeria spp.
waterweed
Overview
Egeria spp. is a small genus of submerged aquatic perennials in the frog-bit family, Hydrocharitaceae, native to South America, with E. densa (Brazilian waterweed) the species most often grown. Plants root in the bed of still and slow-moving fresh water and form long, brittle, branching stems to 2-3 m (7-10 ft), clothed in whorls of three to six narrow, finely toothed, bright green leaves 1-3 cm (0.4-1.2 in) long. Small white flowers with three rounded petals are held at or just above the water surface on slender stalks, mainly in summer. The genus spreads readily from stem fragments, and outside its native range E. densa has become a serious invasive weed in waterways, lakes, and irrigation systems on several continents. It grows in ponds, lakes, ditches, and rivers in full sun to part shade and is widely sold for aquariums and for oxygenating ponds, though sale and transport are restricted in many regions because of its weed status.
Native Range
Native to South America, in the warm-temperate and subtropical fresh waters of Brazil, Argentina, and Uruguay. Plants root in the beds of ponds, lakes, slow rivers, and ditches.Suggested Uses
Grown as a submerged oxygenating plant in ponds and aquariums where it is legal to keep. Used as cover and spawning habitat for fish in ornamental pools, within barriers that keep it from escaping to natural waterways.How to Identify
Appearance
Size & Dimensions
Height7' - 10'
Bloom Information
Small white flowers with three petals open at or just above the water surface, mainly in summer, on slender stalks from the leaf axils. In much of its naturalised range only male plants occur, so seed is rarely set. Spread is mostly by stem fragments rather than seed.
Detailed Descriptions
Foliage Description
bright greenGrowing Conditions
Sun Requirements
Requires 4-10 hours of direct sunlight daily
• Full Sun: 6+ hours of direct sunlight
• Partial Shade: 3-6 hours of direct sunlight
• Full Shade: Less than 3 hours of direct sunlight
Care & Maintenance
Care Guide
Grows submerged in full sun to part shade in still or slow-moving fresh water over a silty or sandy bed. It tolerates a wide range of water chemistry and temperatures but is frost-sensitive at the surface in cold climates. Growth is fast, and stems fragment and re-root easily, so plants can quickly fill a pond. In many regions sale, movement, and disposal are regulated because the genus is an aggressive aquatic weed. Removed material is dried and binned rather than returned to waterways.Pruning
Stems are thinned and trimmed through the growing season to control spread in ponds and tanks. Cuttings are taken from the water rather than left to drift, since fragments re-root. No seasonal pruning is otherwise needed.Pruning Schedule
summer
Container Growing
✓ Suitable for container growing
Minimum container size: 5 gallons