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Giant Spikerush

Eleocharis interstincta (ee-lee-OK-ar-is in-ter-STIK-tah)

Family: Cyperaceae Non-native Herbaceous (3-15 ft)

Giant spikerush is a perennial grasslike rush in the Cyperaceae (sedge) family that grows in the margins of ponds and lakes. It has an upright habit with stems that emerge from thick rhizomes and can reach 4 feet tall. It has no leaves, but it does have long sheaths at the stem base that are often tinged dark-red. The inflorescence is a single, long, cylindrical spikelet at the tip of the stem that is covered with brown, broadly rounded scales. The spikelet has up to 140 small flowers that mature into small, shiny nutlets. The flowers may not be considered showy, however, they are interesting. The stem is segmented with light green lines showing the segment walls. Spreading by rhizomes, large patches of giant spikerush can be formed. This plant grows in freshwater wetlands in full sun and is found in TX, GA and FL in this country but also in Mexico and South America. Ducks, geese, and muskrats all eat portions of this plant. Submerged portions of the plant provide protection to a variety of fish and other water wildlife. Use along ponds and bogs. Insects, Diseases, and Other Plant Problems: No significant problems Salt water and spray can cause the leaves to burn.

Source: NC State Extension Gardener Plant Toolbox ↗ NC State Extension Gardener Plant Toolbox, 51 attributes.

How it fits the guild

Guild layer 4 - Herbaceous (3-15 ft)
See companions & conflicts ↓

Companions & Conflicts

Curated pairwise relationships between this plant and others in the library — who feeds whom, who competes, who confuses the pests. Green reads as a good pairing, red as one to avoid.

No curated interactions recorded for this species yet.

Also noted by NC State

Related species the NC State Plant Toolbox flags for this plant — look-alikes to tell apart, and plants that play a similar role in a planting. Ones we carry in the library are linked.

Full plant profile

Growing Conditions
Plant type
Ground Cover; Herbaceous Perennial; Ornamental Grasses and Sedges
Life cycle
Perennial
USDA zones
9a, 9b, 10a, 10b, 11a, 11b
Light
Full sun (6 or more hours of direct sunlight a day)
Soil texture
High Organic Matter
Soil drainage
Frequent Standing Water | Occasional Flooding
Available space
12 inches-3 feet
Mature size
Height: 1 ft. 0 in. - 4 ft. 0 in. | Width: 1 ft. 0 in. - 3 ft. 0 in.
Growth rate
Medium
Maintenance
Low
Canopy layer
4 - Herbaceous (3-15 ft)
Form & Appearance
Habit / form
Clumping; Erect
Texture
Medium
Leaf color
Green; Red/Burgundy
Leaf type
Sheath
Hairs present
No
Leaf detail
No leaves but has sheathes with a dark reddish color at the base
Flower color
Brown/Copper
Flower value
Showy
Flower form
Spike
Flower size
< 1 inch
Flower detail
Singular spiklet, with 50 to 140 small flowers, and rounded brown scales and stiff short hairs, cylindrical and found at the tip of the stems.
Bloom time
Spring; Summer
Fruit color
Brown/Copper; Gold/Yellow; Gray/Silver
Fruit type
Achene
Fruit size
< 1 inch long, < 1 inch wide
Fruit detail
The small nutlets are smooth and shiny and bulge on both sides. The nutlets that each contains 1 seed do not open when ripe.
Stem color
Green; Red/Burgundy
Stem detail
1/2" diameter segmented hollow, green stems with light green lines up to 4 feet tall.
Wildlife & Ecology
Native status
Non-native
Origin
Tropical and subtropical Americas
Distribution
Alabama, Texas, Georgia and Florida
Wildlife value
The plant is eaten by pond wildlife and provides habitat for waterfowl and fish.
Attracts
Frogs; Small Mammals
Play value
Wildlife Cover/Habitat; Wildlife Food Source
Food & Medicine
Fruit type
Achene

Uses (ethnobotany)

Often used for natural setting landscape and the restoration of habitats.

Landscape Use
Landscape location
Pond; Riparian
Landscape theme
Rain Garden; Water Garden
Garden tags
#lakes #fish #salt intolerant #naturalized area #marshes #drought intolerant #salt spray intolerant #water garden #rain garden #grass #grass-like #waterfowl #wet soils tolerant #freshwater #pond #wetland
Problems & Resistance
Resistant to
Wet Soil
Propagation
Division; Seed

Planted at Hunnicutt

Nobody’s planted this one yet.