- Lemna, from the Greek, lemna,
"water-plant, star-grass, Callitriche verna"
- minor, from the Latin, "lesser"
- Common Name, from its size relative to that of the other common North
American duckweed, Greater Duckweed (Spirodela
- Other common names include: Common Duckweed, Duck's Meat, Lenticule
mineure (Qué), Liden Andemad (Dan), Väike lemmel,
Konnaläätsed, Vesiläätsed, Seauba, Vesivirn,
Päevaseep, Tiigieile (Est), Pikkulimaska (Fin),
Mac gun Athair (Gaelic), Kleine Wasserlinse (Ger),
Klein Kroos (NL), Andmat (Nor), Zaburinka Menšia
(Slovak), Andmat, Vanlig Andmat (Swe)
- Kingdom Plantae, the Plants
- Division Magnoliophyta, the Angiosperms (flowering plants)
- Class Liliopsida, the Monocotyledons
- Subclass Arecidae, the Arum
- Order Arales, the Arum
- Family Lemnaceae, the Duckweeds As a
result of their adaptation to aquatic habitats, they
are among the smallest and simplest of the flowering
plants, floating monocotyledons, only 1-15mm in size.
- Genus Lemna, 13 species worldwide.
- Taxonomic Serial Number: 42590
- Also known as Lemna cyclostasa, Lemna minima
- A ¼, ½, ¾, º, é
- A diminutive floating aquatic perennial, often forming a solid cover
on the surface.
- Leaves and Stems merged in common structure typically
called a frond or thallus, though neither term is correct by strict
botanical definition. The frond itself consists of one to several layers
of conspicuous air spaces and one to several veins.
- Frond flattened, suborbicular to elliptic-obovate in outline;
generally symetrical, with smooth upper surface. The smallest
North Country Duckweed, the fronds rarely exceed 1/8" in diameter. They have three veins. Two budding pouches are locaed on either
side of the basal end. Fronds solitary or in connected clonal
clusters of 2 to 5.
- Root one
- Flower of 2 stamens and a single pistel in a membranous saclike
spathe, hidden away inside the budding pouches. Flowers uncommon.
- Because Duckweed is largely made up of metabolically active cells
with very little structural fiber, the tissue contains twice the protein,
fat, nitrogen, and phosphorus of other vascular plants. Each frond absorbs
nutrients through the whole plant and not through a central root system,
directly assimilating organic molecules such as simple carbohydrates
and various amino acids. With the entire body of the duckweed composed
of non-structural, metabolically active tissue, most photosynthesis
is devoted to the production of protein and nucleic acids, making them
very high in nutrional value.
- Roots to 15 cm, tip mostly rounded; sheath not winged. Stipes white,
small, often decaying. Fronds floating, 1 or 2--5 or more, coherent
in groups, ovate, scarcely gibbous, flat, 1--8 mm, 1.3--2 times as long
as wide, margins entire; veins 3(--5) (if more than 3, outer ones branching
from inner ones), greatest distance between lateral veins near or proximal
to middle; papillae not always distinct (one near apex usually larger);
lower surface very seldom slightly reddish (much less than on upper),
coloring beginning from attachment point of root, upper surface occasionally
diffusely reddish; air spaces 0.3 mm or shorter; distinct turions absent.
Flowers: ovaries 1-ovulate, utricular scale with narrow opening at apex.
Fruits 0.8--1 mm, laterally winged toward apex. Seeds with 8--15 distinct
ribs, staying within fruit wall after ripening.
- Identifiable as a Duckweed by its diminutive size and free-floating
- Distinguished from Greater Duckweed (Spirodela
polyrhiza) by its single root and much smaller size.
- Distinguished from Ivy Leaf Duckweed (Lemna
trisulca) by its small, round fronds.
- Widespread throughout temperate regions of the northern and southern
hemispheres, including North America, Eurasia, Australia, and New Zealand.
- Freshwater ponds, marshes, lakes, and quiet streams.
- Spreads rapidly across quiet bodies of water rich in nutrients, growing
best in water with high levels of nitrogen and phosphate. Iron
is often limiting. Can tolerate a wide pH range, but survives
best between 4.5 and 7.5.
- A cover of duckweed fronds shades the water below and reduces the
growth of algae. Floating duckweed plants are relatively easy
to remove by skimming or are eaten by herbivorous fish. These
traits make duckweeds useful in nutrient removal and bioremediation
- Grows in full sunlight as well as dense shade.
- More cold tolerant than other aquatic vascular plants, and can sustain
temperatures as low as 7º Celcius for normal, practical growth.
Under freezing conditions, will lay dormant on the pond bottom until
warmer conditions return. A full, thick mat of duckweed may have a temperature
of about 10º above ambient air conditions due to radiation
- Wind and wave action can impede duckweed growth and stabilization
by disrupting their ability to attach themselves to each other and form
their characteristic homogenous colonial populations. Optimal
conditions for growth are quiet streams and ponds
- Flowering (rare) late spring--early fall. Mesotrophic to --eutrophic,
quiet waters, in suboceanic, cool-temperate regions with relatively
mild winters; 0--2000 m; St. Pierre and Miquelon; B.C., Ont., Que.,
Sask.; Ala., Ariz., Ark., Calif., Conn., Del., D.C., Fla., Idaho, Ill.,
Ind., Iowa, Kans., Ky., La., Maine, Md., Mass., Mich., Minn., Mo., Mont.,
Nebr., N.H., N.J., N.Mex., N.Y., N.C., N.Dak., Ohio, Okla., Oreg., Pa.,
R.I., S.Dak., Tenn., Utah, Vt., Va., Wash., W.Va., Wis.; w Eurasia;
Africa; Atlantic Islands; Australia (introduced), New Zealand (introduced).
- Natural populations of duckweeds are usually mixtures of several species.
- Trees: Tammarack (Larix
laricina), Black Spruce (Picea
- Shrubs: Bog Birch (Betula
pumila), Leatherleaf (Chamaedaphne
calyculata), Sweet Gale (Myrica
- Herbs: Blue Flag Iris (Iris versicolor), Cattails (Typha
- Ground Covers: Sphagnum Mosses (Sphagnum spp.)
- Mammals: Moose (Alces alces)
- Birds: Great Blue Heron (Ardea herodias)
- ". . . The green mantle of the stagnant pool" (King Lear, Act
III, Scene 4 - A reference to Lemna minor?)
- Very important in the ecosystem as an essential link in the food chain.
- Useful as a water crop as they can acclimatize themselves to almost
all growing conditions, with some thriving in manure-rich or eutrophic
waters. They reproduce quickly, extending over large surface areas,
and are easily harvested. Their high fat and protein content makes
them a source of food for animals and poultry.
- Duckweeds have potential in wastewater treatment, absorbing excess
nutrients from surface waters, including phosphorus and ammonias, reducing
suspended solids, and reducing biochemical oxygen demand.
- Reproduces by seed and vegetatively, thought during the growing season,
nearly all plants arise by vegetative reproduction.
- Unlike the ordinary leaves of most plants, each duckweed frond contains
buds from which more fronds may grow. These buds are hidden in
pouches along the center axis of older fronds. As they grow, new
fronds emerge through slits in the side of their parent fronds. Until
they mature, daughter fronds may remain attached to the parent frond.
Rapidly growing plants often have three or four attached fronds.
- In fall, budding pouches produce smaller, rootless, dark green or
brownish daughter plants called turions. These dense, dormant,
starchfilled structures sink in the fall and rise in the spring due
to changes in starch composition and gas spaces. Other aquatic plants
form turions which are distinctive terminal buds, but Lesser Duckweed
turions are very similar to ordinary fronds, just darker green and a
- Although Duckweed can set seed and produce fruit like other flowering
plants, flowers and seed are uncommon.
- Plants may overwinter as turions, or as seeds, sinking and resting
at the bottom of the pond until they germinate.
- Duckweed reproduce at twice the rate of other vascular plants. Under
ideal conditions, the frond area can double in a few days.
- Hardy to USDA Zone 3 (average minimum annual temperature -40ºF)
- Easily grown in garden ponds, where it removes excess nutrients from
the water while providing surface shade, both of which act to inhibit
- Like most water plants, does best in full sun.
- Goldfish, and other carp, are particularly fond of duckweed. Keep a "starter batch" in a separate, fish free container or pond, if
the fish are too voracious.
- Can be invasive in garden ponds without goldfish, but can be controlled
rather easily by surface skimming with a hand skimmer from a swimming
pool supplier. Just throw it in the compost - it's rich in nutrients.
Last updated on
26 February, 2004