Lemnaceae

Common duckweed Lemna minor, copyright Mokkie.

Belongs within: Araceae.

The Lemnaceae, duckweeds, are a cosmopolitan group of small to minute floating aquatic plants.

Characters (from Healy & Edgar 1980): Very small gregarious aquatic perennials, usually <5 mm long, floating on, or just under, surface of still or slowly moving water, often together forming a complete cover; consisting of ± flattened leafless green platelets, with or without roots, each new platelet arising from a bud in a horizontal pouch on an older platelet. Inflorescence rarely seen, produced in a similar pouch, of 1-2-(3) male flowers maturing successively, and 1 female flower, the whole enclosed within or associated with a membranous spathe. Male flower a single stamen; filament projecting well beyond spathe; pollen sacs 1-2, rounded, splitting transversely; pollen globular. Female flower of rounded ovary and short erect style; carpel single, ovules 1-6, basal. Fruit flattened, sometimes ± winged. Seeds relatively large, smooth or ribbed.

<==Lemnaceae [Spathiflorae]
    |--Telmatosphace gibba [=Lemna gibba] C55
    |--Spirodela Schleiden 1839 ME70
    |    |--S. polyrhiza [=Lemna polyrhiza] HE80
    |    `--S. punctata (Meyer) Thompson 1897 HE80 (see below for synonymy)
    |--Wolffia Horkel ex Schleiden 1839 ME70
    |    |--W. arrhiza (Linnaeus) Wimm. 1857 [=Lemna arrhiza Linnaeus 1771] ME70
    |    `--W. australiana (Bentham) den Hartog & van der Plas 1972 [=W. arrhiza var. australiana Bentham 1878] HE80
    `--Lemna Linnaeus 1753 ME70
         |--L. aequinoctialis LK14
         |--L. disperma ME70
         |    |--L. d. var. disperma ME70
         |    `--L. d. var. fallax ME70
         |--L. minor Linnaeus 1753 ME70
         |--L. paucicostata ME70
         |--L. perpusilla PP07
         `--L. trisulca ME70

Spirodela punctata (Meyer) Thompson 1897 HE80 [=Lemna punctata Meyer 1818 HE80; incl. L. oligorrhiza Kurz 1866 HE80, Spirodela oligorrhiza (Kurz) Hegelm. 1868 ME70]

*Type species of generic name indicated

REFERENCES

[C55] Candolle, A. de. 1855. Géographie Botanique Raisonée: Ou exposition des faits principaux et des lois concernant la distribution géographique des plantes de l’époque actuelle vol. 2. Librairie de Victor Masson: Paris.

[HE80] Healy, A. J., & E. Edgar. 1980. Flora of New Zealand vol. 3. Adventive cyperaceous, petalous and spathaceous monocotyledons. P. D. Hasselberg, Government Printer: Wellington (New Zealand).

[LK14] Lyons, M. N., G. J. Keighery, L. A. Gibson & T. Handasyde. 2014. Flora and vegetation communities of selected islands off the Kimberley coast of Western Australia. Records of the Western Australian Museum Supplement 81: 205–244.

[ME70] Moore, L. B., & E. Edgar. 1970. Flora of New Zealand vol. 2. Indigenous Tracheophyta: Monocotyledones except Gramineae. A. R. Shearer, Government Printer: Wellington (New Zealand).

[PP07] Pandey, R. P., & P. M. Padhye. 2007. Studies on phytodiversity of Arid Machia Safari Park-Kailana in Jodhpur (Rajasthan). Bulletin of the Botanical Survey of India 49 (1-4): 15–78.