Pistia Per Piece

A free-floating, stemless, perennial aquatic herb forming rosettes that resemble heads of lettuce. Rosettes 6–30 cm (2–12 in) across (dwarf forms stay smaller). Leaves are thick, soft, obovate-spathulate, 2–15 cm long, light gray-green, with parallel veins, wavy margins, and a velvety covering of short white hairs that trap air for buoyancy; leaf bases are spongy with large air spaces. Long feathery roots (20–50 cm) hang submerged beneath. Inflorescences are inconspicuous, hidden among leaf bases: a tiny white spathe (5–12 mm) encloses a minute spadix with one basal female flower and 2–8 male flowers above; berries are small green capsules with several seeds. Main reproduction is vegetative via stolons (daughter rosettes form at the ends and break off), so it can quickly form dense mats.

Quick care: full sun to partial shade (best growth with bright light; shade = smaller plants). Requires still or slow-moving fresh water; warm water 22–30 °C (72–86 °F), pH 6.5–7.5, soft to moderately hard. No substrate needed—just float on the surface. Nutrient uptake from water; avoid heavy fertilizers (causes algal blooms). Control spread by thinning regularly; remove excess plants before they cover the surface (blocks light/oxygen, encourages mosquitoes). Not frost-hardy (hardy USDA 8–10; suffers below ∼10–15 °C/50–59 °F). In cold climates treat as annual or overwinter a few rosettes indoors in a bright, warm tub (≥10 °C). Propagate by separating daughter rosettes. Caution: illegal/restricted in many places because it clogs waterways; dispose of excess plants in trash, never into natural waters.