Least duckweed |
Fronds of the least duckweed
| Lemna minuta L.: | |
| Blooming period: | May–September |
| Fronds: | 0.8 to not more than 4 mm long, 1–2 times as long as wide |
| Staminate flowers: | 2, microscopically small, each with only one stamen, sepals and petals missing |
| Pistillate flowers: | 1, microscopically small, sepals and petals missing, style: 1 |
Plant herbaceous, drifting freely in the water, root 0.2–1.5 cm long. No winter buds (turions) are formed.
Fronds symmetrically to almost symmetrical, flat until thickened, on the top dark green to gray green, glossy, fine-grained, with 1 vague vein, which occupies 2/3 of the length between nodes and apex. Plant never reddish.
Fronds entire, rounded at the base, ogival-shaped at the apex, individually or 2–4 fronds contiguous.
Along the center line there is a ridge, which makes the water lens appear roof-shaped.
Lemna minuta blooms very rarely. The tiny inflorescence is surrounded by a membranous spathe, which is open on one side, and consists of a female flower with one ovary, which consists of a single carpel, and 2 flowers, each with one stamen. Petals absent.
After pollination by water spiders and water striders a single-seeded, achene-like fruit is formed, which contains a 0.6–1 mm large seed provided with 12–15 longitudinal ribs.
| Floral formula: |
| ♂ * P0 A1 G0 ♀ * P0 A0 G1 |
Occurrence:
Ponds,
small lakes or peripheral zones of larger lakes or slow moving water
bodies. Prefers nutritious to very nutritious waters.
Distribution:
Originally
Americas. In Japan and Europe naturalized.