Woodrush Flatsedge (Cyperus entrerianus)

Woodrush flatsedge is a perennial, moisture-loving sedge thriving in wetlands and along waterways. Its triangular stems and dense clusters of greenish-brown spikelets rise above grass-like leaves. Notably, its spreading rhizomes form extensive colonies, a testament to its robust adaptability in varied aquatic ecosystems.

I. Appearance and Characteristics 

Cyperus entrerianus, commonly known as the woodrush flatsedge, is a species of sedge that is native to southern parts of North America, Central America, and parts of South America.

The species was first formally described by the botanist Johann Otto Boeckeler in 1878.

The stem of woodrush flatsedge is distinctly triangular in cross-section, exhibiting a 3-sided profile. It is primarily green and has a smooth, firm texture. Typically, the stem can reach up to 3 feet (90 cm) in height and maintains a uniform thickness ranging from 0.1 to 0.3 inches (2.5 to 7.5 mm). The stem usually grows erect with occasional slight bending. A prominent feature is the absence of branches, which helps in distinguishing woodrush flatsedge from other species.

The leaves of woodrush flatsedge are linear, measuring 12-24 inches (30-60 cm) in length and 0.5 inches (1.27 cm) in width. They are basal, flat or V-shaped, with a glossy green surface and a distinctive purple-black base. The texture is smooth and glossy, aiding in water repulsion. These leaves are a prominent feature, with their linear form and unique coloration at the base, crucial for the identification of woodrush flatsedge.

Woodrush flatsedge displays clusters of greenish-white flowers. Terminal flowers comprise 5-11 groups of densely packed spikelets. Each spikelet is small, about 0.2 inches (5 mm) long, tightly arranged in an umbrella-like inflorescence. There is no noticeable scent. These flowers typically bloom in late summer to early autumn, providing visual subtlety with their muted color. The arrangement of spikelets makes them identifiable by their unique texture and structure rather than vibrant hues or large petals.

The fruit of woodrush flatsedge is composed of small, brown achenes that house numerous seeds. In an exceptionally prolific large plant, it can produce up to 1 million seeds. These achenes are typically dry and do not open upon maturity. The size of the achenes is not specified, but achenes generally have a subtle texture and a hardened outer surface. Their brown coloration can aid in camouflage among the soil and dead plant matter, which is a common habitat for woodrush flatsedge. Key identification features of the fruit include its brown hue and the remarkable seed output.

II. How to Grow and Care

Woodrush flatsedge is a relatively low-maintenance plant that thrives in wetland environments. The key care points include ensuring a consistently moist soil environment and providing full to partial sunlight. Woodrush flatsedge is resistant to most pests and diseases, which makes its care easier for both beginners and experienced gardeners.

Sunlight

Woodrush flatsedge will cope well with all levels of sunlight, from full sun to partial shade. However, given a preference, it grows best in full sun. Woodrush flatsedge can also be grown indoors and will cope with less sunlight if grown as a houseplant.

Temperature

Woodrush flatsedge is thought to be native to Madagascar and grows naturally in Africa. Whether in water or soil, woodrush flatsedge will tolerate light frost but not long periods of very cold weather. In cold areas, woodrush flatsedge will die back with the frost but could survive the winter and show new foliage the following season; provided the roots remain unfrozen.

A temperature range of 10 to 22 ℃ is ideal, with a minimum temperature of 4 ℃ acceptable for short periods. High temperatures are not a problem, provided the water supply at the roots is kept continuous.

Watering

Originating from wetlands, woodrush flatsedge thrives in moist environments and exhibits a high tolerance for waterlogged soils. This species is accustomed to consistent moisture and demonstrates a preference for stable hydration. The watering schedule for woodrush flatsedge should reflect its natural affinity for dampness, with a routine of watering every week. As an outdoor plant often found in riparian zones, woodrush flatsedge has adapted to seasonal fluctuations in water availability, which can influence its growth cycles significantly.

Soil

Woodrush flatsedge will grow in any soil, from light and loamy through to heavy clay soils. Likewise, it has no preference towards pH and will grow in acidic, neutral, or alkaline soils. However, it grows best in very wet soils, and can even be grown in standing water up to 30 cm deep.

Fertilizing

Woodrush flatsedge is not a heavy feeder, but small amounts of a standard-strength fertilizer can be applied once a month during active growth periods. Compared to other similar-sized plants, woodrush flatsedge will not consume as much feed.

Planting Instructions

Woodrush flatsedge can be planted from seed, through division or from cuttings. Seeds can either be collected from the plant or bought. These can be sown just under the soil surface, with the soil kept wet. The seedling should appear in a few weeks. When planting woodrush flatsedge in pots, a high loam containing a potting medium should always be used.

In frost-free areas, woodrush flatsedge can spread easily through self-seeding. If the spread is unwanted or becomes a problem, woodrush flatsedge can be planted in a container and flowers picked off before they set seed.

Pruning

In the fall, dead stems should be cut back to prevent unwanted diseases. Care should be taken when pruning woodrush flatsedge, as cutting leaflets will lead to the formation of unsightly brown tips. This is the plant’s natural defense, and cannot be addressed by cutting off the tips in the hope of leaving green growth behind; cutting off the brown leaflets will simply lead to new brown tips. If brown tips have formed for some reason, simply leave them to outgrow as the plant develops.

Propagation

A robust perennial with a proclivity for wet habitats, woodrush flatsedge is predominantly propagated through division. This entails separating the dense clumps that naturally form at the base, ensuring each division contains roots and shoots for successful establishment. Careful handling during separation will minimize stress, promoting quicker recovery and growth in their new environment. To aid in the acclimatization, maintain adequate moisture levels and provide a balanced soil mix conducive to woodrush flatsedge’s growth requirements.

Transplanting

For woodrush flatsedge, the quintessential planting windows span from the vitality of late spring’s warmth to the cusp of summer’s arrival, or as autumn hues give way to early winter’s chill. Choose a spot that offers ample moisture and partial sun. A friendly tip: ensure soil is well-drained to welcome its roots.