Cyperaceae
Isolepis

Isolepis fluitans (L.) R.Br.

First published in Prodr. Fl. Nov. Holland.: 221 (1810)
This species is accepted
The native range of this species is Old World. It is a helophyte or annual and grows primarily in the temperate biome.

Descriptions

Cyperaceae, K Hoenselaar, B. Verdcourt & H. Beentje. Hypolytrum, D Simpson. Fuirena, M Muasya. Flora of Tropical East Africa. 2010

Type
Type: Europe, lectotype Morison 1699 (OXF, lecto.; chosen by Simpson et al. 2001)
Morphology General Habit
Mat-forming short-lived perennial.
Vegetative Multiplication Rhizomes
Rhizome horizontal, green and above ground, 4–30 × 0.3–1.2 mm.
Morphology Culms
Culms 1–47 cm tall, 0.2–1.1 mm diameter, with one or more internodes.
Morphology Reproductive morphology Inflorescences Peduncles
Peducle 1–19 cm tall, 0.2–0.9 mm diameter
Morphology Leaves
Leaves with sheath green or brown, 3–25 × 0.3–1.7 mm; blade 2–80 × 0.2–1.1 mm
Morphology Reproductive morphology Inflorescences
Inflorescence terminal, not proliferating.
Morphology Reproductive morphology Inflorescences Bracts
Bract 2–12 × 0.3–1.3 mm.
Morphology Reproductive morphology Inflorescences Spikelets
Spikelet 1, 2.4–9.4 × 0.7–2.7 mm, with 4–28 glumes.
Morphology Reproductive morphology Inflorescences Bracts Glume
Glumes green or with brown patches, 1.5–3.4 × 0.5–1.3 mm, acute to obtuse, midrib green with mucro < 0.1 mm long
Morphology Reproductive morphology Flowers Androecium Stamens
Stamens 2–3.
Morphology Reproductive morphology Flowers Androecium Stamens Anthers
Anthers 0.4–1.5 mm, crested
Morphology Reproductive morphology Flowers Gynoecium Style
Style bifid
Morphology Reproductive morphology Fruits
Nutlets brown, 0.9–1.8 × 0.5–1.2 mm, minutely reticulate
Figures
Fig. 20, p122
Ecology
Floating in shallow water or terrestrial in seepage and bogs; 1200–3700 m
Distribution
Flora districts: U2 U 3 K 1, K2 K3 K4 K5 K6 T1 T2 T3 T7 Range: Widespread in tropical Africa; Madagascar, Europe, North Africa, India, Australia and New Zealand
[FTEA]

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]

J. Browning, K.D. Gordon-Gray†, M. Lock, H. Beentje, K. Vollesen, K. Bauters, C. Archer, I. Larridon, M. Xanthos, P. Vorster, J. Bruhl, K. Wilson and X. Zhang (2020). Flora Zambesiaca Volume: 14: Cyperaceae. M.Á. García, J.R. Timberlake (Eds). Kew Publish

Type
Europe (England?), n.d., Morison 1699 (OXF lectotype), lectotypified by Simpson et al. in Kew Bull. 56: 1011 (2001).
Morphology General Habit
Aquatic or semi-aquatic, mat-forming, or dryland short-lived perennial; fine roots from branching noded rounded stems 0.2–1 mm diameter
Morphology Leaves
Leaf blade glabrous, often inrolled, eligulate, 1–5 cm long; lateral branches infertile or fertile
Morphology Culms
Culms 2–40 cm tall
Morphology Reproductive morphology Inflorescences
Inflorescence a terminal solitary, elliptic, non-proliferating spikelet, with or without overtopping involucral bract
Morphology Reproductive morphology Inflorescences Spikelets
Spikelets 4–5 × 1–2 mm
Morphology Reproductive morphology Inflorescences Bracts Glume
Glumes 8–10, c. 2 × 1 mm, obtuse, midrib green, with or without mucro, side with 3–4 veins, pale cream with brown patch in upper third
Morphology Reproductive morphology Flowers Androecium Stamens
Stamens 2 (rarely 3)
Morphology Reproductive morphology Flowers Gynoecium Style
Style bifid, 0.5 mm long, branches 1.5 mm long
Morphology Reproductive morphology Fruits
Nutlet 1–1.2 × 0.6–1 mm, faintly trigonous, ovoid to obovoid, apex short conical; smooth to minutely reticulate, pale brown at maturity.
Distribution
Zambia, Zimbabwe, Malawi, Mozambique. Distributed widely across the Old World but absent from the Americas; in Uganda, Kenya, Tanzania, South Africa, Lesotho and Swaziland.
Ecology
Mainly in freshwater streams and along margins of large water bodies, streams in montane grasslands, or as a tufted upright terrestrial plant in frequently damp situations; 1000–2000 m.
Conservation
Widespread; not threatened.
Note
Isolepis fluitans, reported to be non-proliferous, is an extremely variable species collected from all countries within the Flora area except Botswana. It is particularly common in the Eastern Highlands of Zimbabwe. When submerged or floating in freshwater pools the culms, each bearing a single spikelet, rise above the water surface.
[FZ]

IUCN Red List of Threatened Species https://www.iucnredlist.org/species/167850/120171641

Conservation
LC - least concern
[IUCN]

Cyperaceae, Miss S. S. Hooper. Flora of West Tropical Africa 3:2. 1972

Morphology General Habit
Aquatic or semi-aquatic with weak floating or trailing many-noded stems
Ecology
In or near water.
[FWTA]

Sources

  • Angiosperm Extinction Risk Predictions v1

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

  • Flora Zambesiaca

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

  • Flora of Tropical East Africa

    • Flora of Tropical East Africa
    • http://creativecommons.org/licenses/by-nc-sa/3.0

  • Flora of West Tropical Africa

    • Flora of West Tropical Africa
    • http://creativecommons.org/licenses/by-nc-sa/3.0

  • Herbarium Catalogue Specimens

    • 'The Herbarium Catalogue, Royal Botanic Gardens, Kew. Published on the Internet http://www.kew.org/herbcat [accessed on Day Month Year]'. Please enter the date on which you consulted the system.
    • 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 2025. 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 2025. 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