Wolffia arrhiza (L.) Horkel ex Wimm.

Rootless duckweed (en), Lentille deau sans racines (fr), Wolffie sans racines (fr), Lentille d'eau sans racines (fr)

Species

Angiosperms > Alismatales > Araceae > Wolffia

Characteristics

Fronds with round to ovate dorsal outline, usually as long as wide, rarely somewhat longer, 0.8-1.3 by 0.6-0.8 mm; 0.6-0.8 mm high; base and apex obtuse; margin entire or with papillae; dorsal side flat to slightly convex; ventral side strongly inflated, globular, consisting of large cells; width greatest in the dorsal plane; green, without brown pigment cells in the epidermis.
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Perennial herb, hydrophyte. Fronds spherical to ellipsoid, 0.5-1.5 x 0.4-1.2 mm, upper surface shiny, bright green, with 1 basal, lateral, funnel-shaped budding pouch; stomata 10-100. Roots absent. Flowering cavity in upper surface of frond. Inflorescence of 1 female and 1 male flower, without a membranous sheath. Ovary with 1 locule. Seeds 0.4-0.5 x 0.4 mm, globose.
A water plant. It is like a greenish tinge on the water surface. The vegetative part is less than 1 mm long. It is inflated. It is rounded and with 1 side pocket. It does not have roots. The flower breaks through the tip part of the vegetative body. It does not have a spathe or sheath like structure around it. This is made up of one female flower and one male flower.
Perennial, aquatic herb. Roots absent. Fronds floating, spherical to ellipsoid, 1.0-1.3 x as long as wide, biggest width below water surface, shiny and bright green on upper surface, with 10-100 stomata.
Aquatic herb. Fronds globoid to ovoid, 1.0-1.5 times as deep as wide, greatest width below water surface, intensely green on upper side, with 10-100 stomata.
Minute, floating aquatic forming colonies, without roots.
Life form perennial
Growth form herb
Growth support aquatic
Foliage retention evergreen
Sexuality hermaphrodite
Pollination hydrogamy
Spread hydrochory
Mature width (meter) 0.01
Mature height (meter) 0.01
Root system -
Rooting depth (meter) -
Root diameter (meter) -
Flower color
Blooming months -
Fruit color -
Fruiting months -
Nitrogen fixer -
Photosynthetic pathway c3

Environment

A tropical and temperate plant. It grows on the water surface. It can float in rivers. It grows in wetlands.
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Floating on quiet waters. A rare native of southern Britain, growing in still waters.
Stagnant waters, often mixed with other floating aquatics.
Light 7-9
Soil humidity 8-12
Soil texture 1-6
Soil acidity 4-9
Soil nutriment -
Hardiness (USDA) 6-9

Usage

It is used for soup.
Uses animal food fodder
Edible leaves
Therapeutic use -
Human toxicity -
Animal toxicity -

Cultivation

They mostly spread by vegetative means. Daughter plants bud from adult plants. This takes about 3 days.
Mode divisions seedlings
Germination duration (days) -
Germination temperacture (C°) -
Germination luminosity -
Germination treatment -
Minimum temperature (C°) -
Optimum temperature (C°) -
Size -
Vigor -
Productivity -

Images

Leaf

Wolffia arrhiza leaf picture by Sylvain Piry (cc-by-sa)

Distribution

Wolffia arrhiza world distribution map, present in Angola, Australia, Austria, Benin, Burkina Faso, Bangladesh, Bulgaria, Brazil, Botswana, Canada, Czech Republic, Germany, Algeria, Spain, France, Ghana, Guinea-Bissau, Greece, Hungary, Indonesia, Iran (Islamic Republic of), Italy, Kenya, Morocco, Madagascar, Mozambique, Nigeria, Netherlands, Pakistan, Philippines, Korea (Democratic People's Republic of), Portugal, Romania, Russian Federation, Rwanda, Senegal, Togo, Tunisia, Taiwan, Province of China, Tanzania, United Republic of, Uganda, Ukraine, United States of America, and South Africa

Conservation status

Wolffia arrhiza threat status: Least Concern

Identifiers

LSID urn:lsid:ipni.org:names:1044795-2
WFO ID wfo-0000334448
COL ID 5C2XD
BDTFX ID 72993
INPN ID 130119
Wikipedia (EN) Link
Wikipedia (FR) Link

Synonyms

Lemna arrhiza Lemna microscopica Wolffia arrhiza Wolffia delilii Horkelia arrhiza Wolffia michelii Horkelia arrhiza Bruniera vivipara Lenticula arrhiza