Pistia

Scientific name

Pistia L.

Common names

water lettuce

Family

Araceae

Similar genera

unlikely to be confused with any other genus when plants are mature; juvenile plants and seedlings easily confused with Hydrocharis, Limnobium, Phyllanthus, Spirodela

Native distribution

information not available; possibly South America or Africa

Species cultivated

Pistia stratiotes L.

Adventive distribution

most tropical and subtropical regions of the world

Weed status

a noxious weed in numerous countries around the world

Habit

floating, stoloniferous rosetterosette:
(n) a radiating cluster of leaves, usually close to the ground at the base of a plant
plant

Brief description

Perennial, stoloniferous, free-floating. Leaves in rosetterosette:
(n) a radiating cluster of leaves, usually close to the ground at the base of a plant
, sessilesessile:
(adj) attached directly, without a stalk
or short-petiolate; leaf bladeblade:
(n) (syn. lamina) the flat, expanded part of a leaf, frond, or petal (excluding, e.g., the petiole)
obovate, emarginateemarginate:
(adj) with a shallow notch at apex
and sometimes undulateundulate:
(adj) (of, e.g., a margin) with a wavy surface; wavy in the vertical (up and down) plane
apically, densely pubescentpubescent:
(adj) (1) covered with short, soft hairs; (2) bearing hairs
, filled with aerenchymaaerenchyma:
(n) plant tissue with large, gas-filled intercellular spaces that facilitates gaseous exchange and maintains buoyancy
for floatation, venationvenation:
(n) the arrangement of veins in a leaf
parallel. Roots numerous, long, pinnately branched. Inflorescenceinflorescence:
(n) the arrangement of flowers on the floral axis
a small spadixspadix:
(n) a spike of small flowers borne on a thick, fleshy axis
borne on a short, axillaryaxillary:
(adj) in, of, or produced from an axil
peduncle; spathespathe:
(n) a large bract or bracts subtending and often enclosing an inflorescence
green, hairy, tubulartubular:
(adj) (of a corolla, perianth, calyx tube or other structure) (1) tube-shaped; cylindrical: narrow and elongate with more or less straight sides; (2) having segments fused into a tube (of any shape)
below, open above, constricted between male and female parts of spadixspadix:
(n) a spike of small flowers borne on a thick, fleshy axis
; spadixspadix:
(n) a spike of small flowers borne on a thick, fleshy axis
reduced, fused to spathespathe:
(n) a large bract or bracts subtending and often enclosing an inflorescence
on one side. Dispersal by seed and plantlets.

Natural habitat

still waters of most water bodies

Additional comments

Pistia is a highly distinctive genus that consists of a single species, P. stratiotes. The origin of Pistia is speculative, with suggestions that it originated in Africa or North America, based on historical records and fossils. Based on the preponderance of insect herbivores that originate from South America that feed on this plant, it is more plausible that this is the actual origin. Pistia is widely traded as a pond plant and under high nutrient conditions can quickly dominate a water body as a dense, floating monoculture. A 'mini' version is available but is simply juvenile plants grown under less than optimal growning conditions. This form is highly stoloniferous, with flat rounded leaves.