Creeping Water Primrose Identification & Treatment
Scientific Name: Ludwigia spp. (L. peploides, L. grandiflora, L. repens) Category: Emergent Tier: 1 — High-Priority — Most prevalent and/or most damaging across the US
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Identification
Creeping water primrose has shiny, dark green, oval to lance-shaped alternate leaves on long, creeping stems that root at the nodes. Stems can trail across the water surface or extend along the shoreline. Produces bright yellow 5-petaled flowers. Plants often form dense floating mats that extend from the shoreline into open water. Key distinguishing features:
- Trailing/creeping stems that root at nodes
- Shiny, dark green alternate leaves
- Bright yellow 5-petaled flowers
- Forms dense mats extending from shore over water surface
Commonly confused with: Dollar weed/pennywort (round leaves), smartweed (similar growth habit but pinkish flowers and swollen nodes)
Treatment
Recommended Natural Waterscapes Products:
- Glyphosate 5.4 — Systemic herbicide applied to emergent foliage. Most effective in late summer. Glyphosate 5.4
- Clearcast (imazamox) — Systemic herbicide for emergent/floating plants. Clearcast
- Harvester (diquat) — Contact herbicide for visible foliage. Harvester
Full Profile
- Native Range: L. peploides — native to the Americas. L. grandiflora — South America.
- US Distribution: Found across the southern two-thirds of the US. EPA Ecoregions: Southeastern Plains, Southern Coastal Plain, Central California Valley, Mississippi Alluvial Plain, Central Corn Belt Plains. Expanding northward. USDA Zones 5–11.
- Regulatory Status: L. grandiflora is listed as invasive in several states. Not federally listed.
- Habitat: Pond and lake margins, ditches, wetlands, stream banks. Grows in shallow water and saturated soil.
- Reproduction: Primarily vegetative — stem fragments root readily. Also produces seed.
- Ecological Benefits: Provides shoreline stabilization and invertebrate habitat. Flowers attract pollinators. However, dense mats shade out native vegetation, block water flow, and can impede boat access.
- Seasonal Behavior: Active growth spring through fall. Dies back to roots in winter in northern areas. Persistent year-round in southern regions.
Sources: Texas A&M AquaPlant – Water Primrose | USDA PLANTS Database
These species are significant nuisances in multiple EPA ecoregions but may not be encountered as universally as Tier 1 species.
Related Species
- Cattails (Typha latifolia (broadleaf), T. angustifolia (narrowleaf), T. × glauca (hybrid)) — Emergent, Tier 1
- Phragmites (Common Reed) (Phragmites australis subsp. australis (invasive) vs. P. australis subsp. americanus (native)) — Emergent, Tier 1
- Dollar Weed (Pennywort) (Hydrocotyle spp. (H. umbellata, H. ranunculoides, H. verticillata)) — Emergent, Tier 2
- Alligator Weed (Alternanthera philoxeroides) — Emergent, Tier 2
- Flowering Rush (Butomus umbellatus) — Emergent, Tier 3
- Purple Loosestrife (Lythrum salicaria) — Emergent, Tier 3
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