Whorled Watermilfoil
Myriophyllum verticillatum
Whorled watermilfoil is a submerged perennial aquatic plant primarily found in stagnant or slow-moving, nutrient-rich freshwater habitats. The plant is characterized by its finely pinnate leaves, which are typically arranged in whorls of five. In autumn, it develops specialized overwintering buds (turions) that sink to the bottom for survival and vegetative reproduction. Its inconspicuous flowers are arranged in spikes that emerge above the water surface.
Details
Oxygen production
High, especially during the intensive growth phase in summer.
Habitat function
Serves as a 'nursery' for fish and as a colonization space for periphyton organisms.
Nutrient uptake
High capacity for absorbing nitrogen and phosphorus from the water.
Food source for
Waterfowl (e.g., ducks) and various phytophagous insect larvae.
Human use
Used as an ornamental plant in garden ponds and cold-water aquaria.
Ecology
Ecological role
Primary producer; provides habitat for invertebrates and shelter for juvenile fish; contributes to the oxygen supply of the water body.
Natural predators
Waterfowl, herbivorous fish (e.g., rudd), aquatic snails.
Competitor species
Myriophyllum spicatum, Elodea canadensis, Ceratophyllum demersum.
Ecosystem service
Nutrient sequestration, water clarification, erosion protection of the sediment.
Threats
Water pollution, excessive eutrophication, mechanical disturbances from boat traffic.
Scientific profile
Profile
Reproduction
Generative via seeds; vegetative very effective through turions (winter buds) as well as through the rooting of broken shoot fragments.
Protection & threats
Main threats
Excessive eutrophication (leading to algal mats), mechanical weed control, herbicide runoff from agriculture, and destruction of shallow water zones.