Araceae
Wolffia

Wolffia arrhiza (L.) Horkel ex Wimm.

First published in Fl. Schles., ed. 3: 140 (1857)
This species is accepted
The native range of this species is Africa, Europe to N. India, S. Korea to Philippines. It is a hydroannual and grows primarily in the subtropical biome.

Descriptions

J. R. Timberlake, E. S. Martins (2012). Flora Zambesiaca, Vol 12 (part 1) Araceae. Royal Botanic Gardens, Kew

Morphology Leaves
Frond spherical to ellipsoid, 0.5–1 × 0.4–1.2 mm, 1–1.3 times as long as wide, 1.25–1.5 times as deep as wide; upper surface bright green
Morphology Reproductive morphology Inflorescences
Inflorescence occasionally produced
Morphology General Habit
Plants rarely fruiting; seed 0.4–0.5 × c.0.4 mm;
Distribution
Botswana, Mozambique. Found in temperate, subtropical and tropical regions of Europe, Western Asia and Africa; introduced to Brazil.
Ecology
Often forming large populations on water surface of pools, sheltered lakes and in ditches; 10–1000 m.
Conservation
Widespread; not threatened.
[FZ]

Extinction risk predictions for the world's flowering plants to support their conservation (2024). Bachman, S.P., Brown, M.J.M., Leão, T.C.C., Lughadha, E.N., Walker, B.E. https://nph.onlinelibrary.wiley.com/doi/full/10.1111/nph.19592

Conservation
Predicted extinction risk: not threatened. Confidence: confident
[AERP]

IUCN Red List of Threatened Species https://www.iucnredlist.org/species/164241/120209232

Conservation
LC - least concern
[IUCN]

CATE Araceae, 17 Dec 2011. araceae.e-monocot.org

Diagnostic
Fronds with 10-100 stomata, on the upper surface relatively deep green (not transparrent).
Distribution
Temperate, subtropical and tropical regions of Europe, Africa, western Asia and eastern Brazil with relatively mild winters and not very hot summers.
General Description
Fronds spherical to ellipsoid, with the greatest width just below the surface of the water, 0.5-1.5 mm long, 0.4-1.2 mm wide, 1-1 1/3 times as long as wide, 1 1/4-1 1/2 times as deep as wide, with 10-100 stomata, bright green on the surface (not transparent). INFLORESCENCE: Plants occasionally flowering and rarely fruiting. INFRUCTESCENCE: Seeds 0.4-0.5 mm long, about 0.4 mm thick.
[CATE]

Sources

  • Angiosperm Extinction Risk Predictions v1

    • Angiosperm Threat Predictions
    • http://creativecommons.org/licenses/by/4.0

  • CATE Araceae

    • Haigh, A., Clark, B., Reynolds, L., Mayo, S.J., Croat, T.B., Lay, L., Boyce, P.C., Mora, M., Bogner, J., Sellaro, M., Wong, S.Y., Kostelac, C., Grayum, M.H., Keating, R.C., Ruckert, G., Naylor, M.F. and Hay, A., CATE Araceae, 17 Dec 2011.
    • http://creativecommons.org/licenses/by-nc-sa/3.0

  • Flora Zambesiaca

    • Flora Zambesiaca
    • http://creativecommons.org/licenses/by-nc-sa/3.0

  • Herbarium Catalogue Specimens

    • Digital Image © Board of Trustees, RBG Kew http://creativecommons.org/licenses/by/3.0/

  • IUCN Categories

    • IUCN Red List of Threatened Species
    • http://creativecommons.org/licenses/by-nc-sa/3.0

  • Kew Backbone Distributions

    • The International Plant Names Index and World Checklist of Vascular Plants 2024. Published on the Internet at http://www.ipni.org and https://powo.science.kew.org/
    • © Copyright 2023 World Checklist of Vascular Plants. http://creativecommons.org/licenses/by/3.0

  • Kew Names and Taxonomic Backbone

    • The International Plant Names Index and World Checklist of Vascular Plants 2024. Published on the Internet at http://www.ipni.org and https://powo.science.kew.org/
    • © Copyright 2023 International Plant Names Index and World Checklist of Vascular Plants. http://creativecommons.org/licenses/by/3.0

  • Kew Science Photographs

    • Copyright applied to individual images