Potamogeton, Genus, spp., Multiple species,
- Genus
- Multiple species
pondweeds
Cosmopolitan - fresh waters of all continents except Antarctica
Overview
Potamogeton is a cosmopolitan genus of about 70 to 90 submerged and floating-leaved perennial water plants in the family Potamogetonaceae, the pondweeds. Plants root in the bed of lakes, ponds, rivers, and ditches and spread by creeping rhizomes, sending up slender stems 1-6 ft (0.3-1.8 m) long. Many species bear two leaf forms: thin, translucent, often wavy submerged leaves and tougher, leathery floating leaves that rest on the surface. Small greenish flowers crowd into short spikes that stick up just above the water and are pollinated by wind and water; rounded nutlets follow. Species range across fresh waters worldwide, from cold lakes to warm ditches, and several tolerate slightly brackish or calcareous water. Pondweeds are a key wildlife food in fresh water, with the foliage, tubers, and seeds eaten by waterfowl, fish, and aquatic insects. A few, such as curly-leaf pondweed P. crispus, have naturalized outside their range and form dense weedy beds. Growth can clog small waters and slow channels.
Native Range
Potamogeton occurs in fresh waters on every continent except Antarctica, with native species across North America, Eurasia, Africa, and Australia. Many species are native and widespread throughout North America. The genus grows in lakes, ponds, slow rivers, streams, and ditches, in water from a few inches to several feet deep.Suggested Uses
Grown in wildlife ponds, lakes, and large water gardens as a submerged oxygenating plant that shelters fish and feeds waterfowl. The floating-leaved species give surface cover and shade that cools the water. Used in pond restoration and habitat plantings rather than as an ornamental feature.How to Identify
Appearance
Size & Dimensions
Height1' - 6'
Width/Spread1' - 5'
Bloom Information
Potamogeton flowers from late spring through summer, lifting short greenish spikes above the water for wind and water pollination. The flowers are small and easy to miss, and fruiting follows over the warm months. Flowering depends on water level, as spikes must reach the surface to open.
Detailed Descriptions
Flower Description
Greenish, inconspicuousFoliage Description
Translucent green to olive, floating leaves leathery greenGrowing Conditions
Sun Requirements
Requires 4-8 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
Potamogeton grows rooted in the sediment of still to slow-moving fresh water in full sun to part shade, in depths from a few inches to several feet. Plants need permanent water and a soft silt, sand, or organic bed, and they tolerate a wide pH, with many species favoring neutral to alkaline water. Most are hardy through cold winters, dying back and overwintering as rhizomes or specialized buds called turions. Growth can be vigorous, and dense beds may need thinning in ornamental ponds. Shading from algae blooms or turbid water reduces growth.Pruning
Excess stems are raked or cut from ponds in summer to keep open water and prevent dense mats. Cut material is left briefly at the water's edge so aquatic animals can return to the pond, then composted. Curly-leaf pondweed in particular is removed before it sets turions to slow its spread.Container Growing
Suitable for container growing
Minimum container size: 2 gallons
