OregonFlora species comparison

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Spirodela polyrrhiza

Spirodela

greater duckweed

duckweed
Habit Plants free-floating aquatics, on the surface; green, sometimes reddish, flat plant bodies without true stems and leaves; veins 7–16.
Roots

up to 3 cm long.

7–21.
Buds

formed in 2 lateral pouches; turions present or absent.
Turions

1–2 mm diameter; greenish brown.

Inflorescences

a single flower in a membranous spathe within the budding pouch, rarely produced.
Flowers

bisexual;

tepals 0;

stamens 2.
Fruits

1–2(5) seeded follicles.
Plant bodies

(3)5–10 mm long, 1–1.5 times longer than wide, orbicular to obovate, 7–16 veins;

lower surface flat; reddish purple;

upper surface green, usually with a reddish purple spot above the root attachment, generally in clusters of 2–5 or solitary.

2n

=30, 38, 40, 50, 80.

Spirodela polyrrhiza

Spirodela
Distribution
[WildflowerSearch map]
[BONAP county map]
Discussion

0–1700 m. BR, Casc, Est, Sisk, WV. CA, ID, NV, WA; throughout North America; temperate and tropical regions worldwide. Native.

There are pigment cells in the epidermis of Spirodela species that are visible in dead plants as brown dots.

Freshwater. Cosmopolitan. 2 species; 1 species treated in Flora.
Source Flora of Oregon, volume 1, page 150
Katie Mitchell		 Flora of Oregon, volume 1, page 150
Katie Mitchell
Subordinate taxa
S. polyrrhiza
Web links 
Unless otherwise noted, all data comes from OregonFlora.



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