Water Hyacinth (Not a true grass, aquatic plant often mistaken for aquatic vegetation/grassland weed)
Pontederia crassipes · Warm-season perennial aquatic floating plant
Grass Family
Pontederiaceae (Pickerelweed family)
Grass Category
Invasive/Weed Aquatic Plant
Variety / Cultivar
Wild type
Hardiness Zones
USDA Hardiness Zones 9-11 (killed by freezing temperatures)
About This Grass
Free-floating aquatic perennial with glossy, rounded, thick leaves and bulbous petioles filled with air cells. Produces spikes of light blue to violet flowers.
Blade Characteristics
Not a true grass; features rounded to kidney-shaped leaves with spongy, inflated petioles, smooth texture, and parallel-curved venation.
Root System
Feathery, dark purple or black dangling roots that hang freely in the water without anchoring in soil.
Growing Information
Origin Region
Amazon basin, South America; naturalized worldwide in tropical and subtropical regions
Growth Habit
Free-floating aquatic plant spreading rapidly via stolons and offsets
Sunlight & Water Needs
Full sun to partial shade, thrives in nutrient-rich still or slow-moving water bodies like ponds and lakes.
Mowing & Maintenance
Not applicable to mowing; requires manual or mechanical removal or biological control due to invasive tendencies.
Special Characteristics
Extremely fast growth rate, can double its population in two weeks, highly invasive, clogs waterways and disrupts aquatic ecosystems.
Ecological Information
Considered one of the worst aquatic weeds globally; forms dense mats that block sunlight, deplete oxygen, and outcompete native aquatic life.