Common Name: Duckweeds
Description: Herb floating at water surface, solitary or 2 thalli remaining connected. Roots absent. Thallus symmetric, thick, ± globose, ellipsoid or ovoid, the greatest part of the thallus submerged, green; veins not visible; dorsal and ventral scale absent. Budding pouch with lateral (actually basal) slit.
Inflorescence of 1 female and 1 male flower; bract absent. Anther 1-locular.
Distribution and occurrence: World: at least 7 spp., temp. & trop. regions. Aust.: 3 spp. (1 sp. endemic), Qld, N.S.W., Vic., S.A., W.A.
Wolffia was formerly placed in Lemnaceae.
Text by B.J. Conn, Flora of New South Wales Vol. 4: 38 (1993), in Lemnaceae
Taxon concept: Australian Plant Census (accessed May 2017)
| ||Key to the species|| |
|1||Thallus globose to ovoid, 1–1.5 times as deep as broad, biggest breadth below the water surface||Wolffia globosa|
|Thallus boat-like, 2–3 times as deep as broad, biggest breadth near the water surface||2|
|2||Thallus 0.3–0.8 mm wide, length to breadth ratio 1.3–2, depth 1.3–2 times length of upper surface; upper surface uniformly green and shining, slightly convex and rounded laterally, with 50–80 stomata||Wolffia australiana|
|Thallus 0.2–0.5 mm wide, length to breadth ratio 1.6–3.5, depth 2–3 times length of upper surface; upper surface whitish green towards central part, green near 'margin', flat and sharply edged laterally, with 8–25 stomata|
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