Cyperus polystachyos
Common name
bunchy sedge
Synonyms
Pycreus polystachyos (Rottb.) Domin
Family
Cyperaceae
Flora category
Vascular – Exotic
Structural class
Sedges
Conservation status
Not applicable
Brief description
Tufted yellow-green leafy sedge, with triangular stems up to 50 cm tall, leaves arranged in threes, with up to 7 upright yellow-green to pale brown ragged flowerheads, each made up of narrow flattened flower spikes, with 3 to 6 long grass-like leaves immediately under this, at the end of flower stalk.
Distribution
Restricted to Northland and Auckland where it is locally common.
Habitat
Wet pasture, margins of water bodies and drains.
Wetland plant indicator status rating
Information derived from the revised national wetland plant list prepared to assist councils in delineating and monitoring wetlands (Clarkson et al., 2021 Manaaki Whenua – Landcare Research Contract Report LC3975 for Hawke’s Bay Regional Council). The national plant list categorises plants by the extent to which they are found in wetlands and not ‘drylands’. The indicator status ratings are OBL (obligate wetland), FACW (facultative wetland), FAC (facultative), FACU (facultative upland), and UPL (obligate upland). If you have suggestions for the Wetland Indicator Status Rating, please contact: [Enable JavaScript to view protected content]
FACW: Facultative Wetland
Usually is a hydrophyte but occasionally found in uplands (non-wetlands).
Detailed description
Densely tufted annual to perennial. Stems to 50 cm tall, 3-angled, leafy at base. Leaves < stems, 2–3 mm wide, smooth; sheaths purple-brown, sometimes with a few transverse septa. Involucral bracts 3–6, leaf-like, > inflorescence. Inflorescence capitate or with rays to 4 cm long. Spikelets ± stiffly erect in rather dense clusters, narrow-linear, acute, ± 15 × 1.5 mm. Glumes ± 2 mm long, densely imbricate, membranous, subobtuse, chestnut or straw-coloured with green keel. Stamens 2. style-branches 2. Nut ± ½ length of glume, oblong, compressed-biconvex, brown.
Similar taxa
Similar to and often growing with Cyperus eragrostis and C. congestus, differring by the upright, close set inflorescence, the flowerheads are not globular.
Flowering
Summer to autumn
Flower colours
Brown, Green
Fruiting
Summer to autumn
Life cycle
Seed dispersed by contaminated machinery.
Year naturalised
1953
Origin
Pantropical and subtropical, also more temperate Australia
Reason for introduction
Unknown, possibly ornamental plant, seed or soil contaminant.
Control techniques
Not controlled in New Zealand.
Etymology
cyperus: From the ancient Greek name for sedge, kypeiros
Attribution
Factsheet prepared by Paul Champion and Deborah Hofstra (NIWA). Features description from Healy and Edgar (1980).
References and further reading
Champion P. et al. 2020. Freshwater Invasive Species of New Zealand 2020. NIWA publication. https://docs.niwa.co.nz/library/public/FreInSpec.pdf
Healy AJ, Edgar E. 1980. Flora of New Zealand, Volume III. Adventive Cyperaceous, Petalous and Spathaceous Monocotyledons. Government Printer, Wellington, NZ. 220 p.
Johnson PN, Brooke PA. 1989. Wetland plants in New Zealand. DSIR Field Guide, DSIR Publishing, Wellington, NZ. 319 p.