Floating Sweet-grass
Glyceria fluitans
Floating Sweet-grass is a perennial grass species that primarily grows in shallow, stagnant, or slow-moving waters. The stems can reach lengths of up to 150 centimeters and frequently float on the water's surface, which gives the species its common name. The leaves are narrow, light green, and feature a characteristic hood-shaped tip along with a rough texture. During its flowering period, the plant produces long, narrow panicles with greenish to purplish spikelets. Historically, the species was economically significant as a source of manna seeds, used as a cereal grain.
Details
Oxygen production
Minor oxygen release through the submerged parts of the plant.
Habitat function
Important habitat for caddisfly larvae and spawning site for amphibians.
Nutrient uptake
High; efficiently filters nitrogen and phosphorus from the water and sediment.
Food source for
Waterfowl, herbivorous fish, insect larvae, formerly also human nutrition.
Human use
Formerly collected for its sweet seeds to produce groats (manna croup); today occasionally used as an ornamental grass for ponds.
Ecology
Ecological role
Primary producer; provides shelter for juvenile fish and aquatic invertebrates; serves as nesting material and food for waterfowl.
Natural predators
Waterfowl (e.g., ducks), muskrats, grazing livestock.
Competitor species
Great Manna-grass (Glyceria maxima), Common Reed (Phragmites australis), Reed Canary Grass (Phalaris arundinacea).
Ecosystem service
Shoreline stabilization, nutrient removal from the water body, provision of habitat.
Threats
Drainage of wetlands, intensive shoreline construction, excessive herbicide use near water bodies.
Scientific profile
Profile
Reproduction
Generative reproduction via seeds (hydrochory and epizoochory) as well as effective vegetative reproduction via creeping rhizomes and rooting of stem nodes.
Protection & threats
Main threats
Destruction of wetlands through drainage, intensive agricultural use of riparian zones, and herbicide input.