Flora of North America species comparison

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Pistia stratiotes

apon-apon, laitue d'eau, lechuguita de agua, pistie, tropical duckweed, water-lettuce
Roots

to 50 cm, with short branches.
Leaves

light green to grayish green, 2–15(–20) cm, spongy, pubescence dense, white;

major veins 5–13(–15), nearly parallel, abaxially prominent.
Inflorescences

spathe white to pale green, convolute basally, slightly constricted above middle, spreading apically, pwhite to pale green, pubescent outside, glabrous inside;

spadix adnate to spathe more than 1/2 its length, shorter than spathe;

axis naked at base of staminate part and sometimes extending beyond staminate flowers.
Flowers

staminate flowers (2–)6–8, in single whorl around central stalk, stamens 2, connate;

pistillate flower solitary;

ovariesy 1-locular, 4–5 mm;

ovules 4–15(–20), orthotropous;

styles ca. 3 mm;

stigmas obtuse, with small hairs.
Fruits

with thin pericarp.
Seeds

light brown, cylindric, 2 × 1 mm.
; staminate flowers (2–)6–8, in single whorl around central stalk; stamens 2, connate.

2n

= 28 (India, Borneo).

Pistia stratiotes
Phenology Flowering mainly late summer–early winter (although; plants have been collected in flower in almost all months).
Habitat Slow-moving streams, canals, drainage ditches, ponds, lakes, and springs
Elevation 0–10 m (0–0 ft)
Distribution
from FNA
FL; LA; TX; Mexico; Central America; South America; West Indies; Asia; Africa; Pacific Islands; Australia
[WildflowerSearch map]
[BONAP county map]
Discussion

Pistia stratiotes has been collected north and west of its U.S. range in Arizona, California, Georgia, Missouri, New Jersey, Ohio, and South Carolina. These are probably populations that do not persist. Although P. stratiotes is often reported as occurring from Florida to Texas, I saw no verifying herbarium specimens from Alabama or Mississippi, nor were any populations located during my fieldwork in those states.

(Discussion copyrighted by Flora of North America; reprinted with permission.)
Source FNA vol. 22.
Parent taxa Araceae > Pistia
Synonyms P. spathulata
Name authority Linnaeus: Sp. Pl. 2: 963. (1753)
Web links 
Unless otherwise noted, all data comes from the online version of the Flora of North America, who have made most of their content available via a Creative Commons license (CC BY 4.0).



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