Pistia stratiotes – Water Lettuce

Pistia stratiotes - Water Lettuce, Water-lettuce

Pistia stratiotes - Water Lettuce, Water-lettuce

Plant Name

Scientific Name: Pistia stratiotes

Common Names: Water Lettuce, Water-lettuce

Plant Characteristics

Duration: Perennial

Growth Habit: Herb/Forb

Hawaii Native Status: Introduced. This naturalized ornamental water garden plant is native to tropical America, but it is now a pan-tropical water weed.

Flower Color: Inconspicuous (white, pale green)

Height: Up to 8 inches (20 cm) tall, but usually less

Description: The tiny flowers have a white to pale green spathe and are followed by small, green, berrylike fruit. The leaves are whorled in small, lettuce-like rosettes that float on the surface of the water. The leaf blades are pale green, spongy, velvety-hairy, lined with indented parallel veins, sessile, wedge-shaped, and waterproof (water beads up and slides off of them). The roots dangle in the water and are up to 20 inches (50 cm) long. The plants usually propagate by stolons (creeping stems bearing cloned new plants).

These weedy aquatic plants can completely take over ponds, marshes, and slow-moving streams and canals, choking out native aquatic plants and disrupting the aquatic ecosystem.

Special Characteristics

Poisonous – The plants contain needle-like calcium oxalate crystals that can cause intense mouth burning and swelling along with gastrointestinal upset if ingested. These plants also absorb toxic metals from the water.

Classification

Kingdom: Plantae – Plants
Subkingdom: Tracheobionta – Vascular plants
Superdivision: Spermatophyta – Seed plants
Division: Magnoliophyta – Flowering plants
Class: Liliopsida – Monocotyledons
Subclass: Arecidae
Order: Arales
Family: Araceae – Arum family
Genus: Pistia L. – pistia
Species: Pistia stratiotes L. – water lettuce

More About This Plant

Hawaii County Distribution Map