Wolffia

Horkel ex Schleiden

Beitrage zur Botanik 1: 233. 1844.

Common names: Water-meal
Etymology: for Johann. F.riedrich Wolff, 1778–1806, German physician
Treatment appears in FNA Volume 22. Treatment on page 151.
 TaxonIllustrator 
FNA22 P27 Spirodela Lemna Wolffiella Wolffia pg 146.jpegLemna minor
Spirodela punctata
Lemna trisulca
Wolffia borealis
Lemna obscura
Wolffia arrhiza
Wolffia columbiana
Lemna minuta
Lemna perpusilla
Wolffiella gladiata
Spirodela polyrrhiza
Lemna turionifera
Lemna valdiviana
Wolffiella lingulata
Lemna gibba
Wolffia brasiliensis
Lemna aequinoctialis
Wolffiella oblonga
Wolffia globosa
John Myers
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John Myers

Roots absent. Fronds floating or submersed (only turions sink to bottom), 1 or 2, coherent, each frond globular, ovoid, or boatshaped, 3-dimensional, smaller than 1.6 mm, margins entire; air spaces not in tissue; reproductive cavity terminal, at base from which daughter fronds (but no flowers) originate, conic, lower side of cavity with short tract of elongated cells along median line forming connection between node and attachment to mother frond; veins 0; scale at base of frond absent; anthocyanins absent; in some species pigment cells present (visible in dead fronds as brown dots); turions light green, globular, smaller than growing fronds. Flowers 1 per frond, originating in cavity ± on median line of upper frond surface, not surrounded by utricular scale; stamen 1, 2-locular. Seeds 1, nearly smooth. x = 10, 20, 21, 22, 23.

Distribution

Nearly worldwide (except arctic and antarctic regions)

Discussion

Species 11 (5 in the flora).

Selected References

None.

Key

1 Fronds boat-shaped, 0.3–1 times as deep as wide, with pigment cells in vegetative tissue. > 2
1 Fronds globular to ovoid, 1–1.5 times as deep as wide, without pigment cells in the vegetative tissue. > 3
2 Fronds 1–1.5 times as long as wide, rounded at apex, papilla usually prominent in center of upper surface Wolffia brasiliensis
2 Fronds 1.3–2 times as long as wide, with point at apex bent upwards, papilla absent Wolffia borealis
3 Fronds with 10–100 stomates, slightly pointed at apex, the adaxial upper surface intensely green (not transparent) Wolffia arrhiza
3 Fronds with 1–10(–30) stomates, rounded or slightly pointed at apex, upper surface transparently green. > 4
4 Fronds 1.3–2 times as long as wide, 0.3–0.5 mm wide Wolffia globosa
4 Fronds 1–1.3 times as long as wide, 0.4–1.2 mm wide Wolffia columbiana
... more about "Wolffia"
Elias Landolt +
Horkel ex Schleiden +
small green +
Water-meal +
Nearly worldwide (except arctic and antarctic regions) +
for Johann. F.riedrich Wolff, 1778–1806, German physician +
coherent +
submersed +  and floating +
2 +  and 1 +
boat-shaped +, ovoid +  and globular +
1.6 cm16 mm <br />0.016 m <br /> (?) +
not differentiated +
tapering +  and bottle--shaped +
Beitrage zur Botanik +
distinct +
funnel--shaped +
Wolffia +
Lemnaceae +
light green +
globular +
smaller +
submersed +  and floating +
23 +, 22 +, 21 +, 20 +  and 10 +