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Dune Sedge
Cyperus laevigatus
SA tree number
English: Dune Sedge, Sand Dune Sedge, Smooth Flat Sedge, Smooth Flatsedge, Boredrain Sedge
Afrikaans: Rivierkweek
Misapplied or old scientific names: Scirpus laevigatus, Juncellus laevigatus, Carex arenicola
Historical scientific names: Acorellus laevigatus, Cyperus mucronatus, Juncellus laevigatus, Pycreus laevigatus
Subspecies: Cyperus laevigatus subsp. distachyos, Cyperus laevigatus subsp. laevigatus
Cyperus laevigatus, commonly known as Dune Sedge, Smooth Flat Sedge or Rivierkweek, is a widespread perennial sedge that thrives in wet and often saline or alkaline environments. It is a distinctive grass-like plant, characterised by its smooth, cylindrical stems and inconspicuous flower clusters that appear to emerge from the side of the stem.
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Distinguishing features
Grows as a perennial sedge, reaching up to 95 cm tall.
Often forms dense clumps or mats interconnected by a horizontal rhizome.
Stems (culms) are typically rounded to triangular, appearing smooth and rush-like.
The inflorescence is a small, capitate (head-like) cluster of cylindrical spikelets, often with a single upright, leaf-like bract that makes the inflorescence appear to be lateral.
Spikelets vary in colour from green to reddish to dark brown.
Overall appearance:
Cyperus laevigatus is a creeping, rush-like sedge that varies in size, forming tufted clumps or spreading colonies from a long rhizome.
Height:
Can grow from 3 cm up to 95 cm tall.
Width:
Forms dense mats or vast stands; specific clump width is variable depending on growing conditions.
Leaves:
Leaves are often reduced to short sheaths, but when present, leaf blades are linear, inrolled, and almost culm-like, typically 2.2–6.5 cm long and 0.5–2 mm wide.
Flowers:
The inflorescence is a small, capitate (head-like) cluster of sessile (stalkless) spikelets. It is often green to reddish or dark brown, with one to three leaflike bracts at the base, one of which is usually upright and continues in the direction of the culm, making the inflorescence appear lateral. Dioecious nature (separate male and female plants) is not commonly noted for this species, it is usually bisexual or monoecious.
Flowering season:
Flowers can appear throughout the year, depending on conditions.
Fruits:
Produces small, grey to brown, shiny nutlets (achenes) that are obovoid to ellipsoid in shape, typically 1.4–2.1 mm long and 0.8–1.2 mm wide. They are flat on one side and rounded on the other.
Seeds:
Contained within the nutlets, smooth.
Stems:
Culms are tufted or spaced along the rhizome, typically 3–95 cm long and 0.5–4.4 mm wide. They are generally rounded to trigonous (three-angled), sometimes triquetrous (sharply three-angled), and appear smooth or polished.
Roots:
Possesses a long, creeping rhizome, 1–5 mm in diameter, which can extend 30 cm or more, facilitating its spread and forming dense mats.
Soil type:
Thrives in wet areas, especially along lake shores, streambanks, in temporary pools, flood areas, near hot springs, and in hollows of coastal dunes. It prefers moist to wet, sandy or loamy soils, and is highly tolerant of brackish water, saline, or alkaline conditions.
Aspect:
Prefers full sun to partial shade.
Edibility:
Information regarding the edibility of Cyperus laevigatus for human consumption is not widely documented in general sources. In some cultures, parts of Cyperus species may be used medicinally, but specific traditional uses for this particular species should be consulted with local botanical knowledge.
Toxicity:
No information regarding the toxicity of Cyperus laevigatus was found.
Uses:
Extensively used in some cultures for weaving mats.
A valuable plant for erosion control in wetlands, helping to stabilise soil and sediment.
Often used in landscaping, particularly for waterside planting near water features and ponds, due to its attractive foliage and ability to thrive in wet conditions.
Ecology:
As a wetland plant, Cyperus laevigatus plays a significant role in its ecosystem. It provides habitat and shelter for various wildlife species, including birds and aquatic insects. Its dense growth helps to filter pollutants from water, contributing to water quality. It often forms dense monospecific stands (areas dominated by only this species) around saline or alkaline hot springs and lake shores.
Distribution and habitat:
Cyperus laevigatus is widespread across tropical and subtropical regions globally, including the Americas, Africa, the Mediterranean Basin, the Middle East, India, Central Asia, Australia, and various oceanic islands. In South Africa, it is found in many regions, typically in wetlands, on the margins of brackish pools, lake shores, and riverbanks.
Derivation of name:
The genus name Cyperus comes from the Latin 'cyperos', derived from the Greek 'kypeiros', an ancient Greek name for various sedge plants.
The specific epithet laevigatus is from Latin, meaning "smooth" or "polished," referring to its smooth and often shiny stems.
Historical aspects:
This sedge has been recognised and utilised in various cultures for its properties, particularly for crafts like mat weaving, as noted in Hawai'i where it is known as 'makaloa'. Its ability to thrive in diverse wetland conditions has made it a notable species across many continents.
Interesting facts
Cyperus laevigatus is a true survivor, capable of growing in some of the most challenging environments, including hot springs and highly saline soils where few other plants can flourish!
Despite being a "sedge," its smooth, rush-like stems can sometimes make it look more like a grass or a reed, showcasing nature's clever adaptations.
The way its inflorescence appears to emerge from the side of the stem, rather than the top, is a cool botanical trick that helps distinguish it!
Growing tips
Prefers consistently moist to wet conditions, so it's ideal for water gardens, pond margins, or boggy areas.
Plant in full sun to partial shade for optimal growth.
It can tolerate a wide range of soil types, including sandy, loamy, and even saline soils, as long as they remain moist.
Consider using it for erosion control in wetland or waterside areas, as its rhizomatous root system helps stabilise soil.
This plant is a fantastic alternative for:
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