Cyperus congestus
Common names
purple umbrella sedge
Biostatus
Exotic
Category
Vascular
Structural class
Sedges
Simplified description
Tufted leafy sedge, with triangular stems with a swollen base, up to 80 cm tall, leaves arranged in threes, with a single or group of up to 7 red-purple round 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.
Flower colours
Green, Red/Pink
Detailed description
Thickly tufted perennial. Stems 15–40–(80) cm high, rather robust, 3-angled, smooth, leafy and somewhat bulbous and woody at base. Leaves usually < stems, to 7 mm wide, flat, margins smooth below, scabrid towards tip; sheaths purple-brown, minute transverse septa evident. Involucral bracts 3–6, leaf-like, the lowest > inflorescence. Inflorescence a simple or compound umbel or reduced to a single head; rays 2–4, rather rigid, to 6 cm long. Spikelets numerous, 10–20 × 2 mm, narrow-linear, acute, in dense ovate or hemispherical reddish-purple spikes; rhachilla with membranous wings. Glumes ± 3 mm long, not closely imbricate, usually tightly appressed to rhachilla, oblong-elliptic, acute, many-nerved, keel green, margins deep red-purple. Stamens 3. Style-branches 3. Nut ± ½ length of glume, obovoid-oblong, trigonous, dark brown, apiculate.
Similar taxa
Similar to other Cyperus species, distinguished from the only other species with red-purple flowers (C. rotundus) by the lack of rhizomes and tubers and much taller growth habit.
Distribution
Scattered throughout the North Island and Nelson, Marlborough and Canterbury, locally common in many areas.
Habitat
Wet areas such as the banks of rivers and streams, swamps, ditches and also a weed of drier sites such as roadsides and cropping land.
Conservation status
Not applicable
Detailed taxonomy
Family
Ecology
Flowering
Summer to autumn
Fruiting
Summer to autumn
Year naturalised
1878
Origin
South Africa
Reason for introduction
Unknown, possibly ornamental plant, seed or soil contaminant.
Control techniques
Can be controlled manually, mechanically or herbicidally depending on situation.
Life cycle and dispersal
Seed dispersed by contaminated machinery.
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]
FAC: Facultative
Commonly occurs as either a hydrophyte or non-hydrophyte (non-wetlands).
Other information
Etymology
cyperus: From the ancient Greek name for sedge, kypeiros
NVS code
The National Vegetation Survey (NVS) Databank is a physical archive and electronic databank containing records of over 94,000 vegetation survey plots - including data from over 19,000 permanent plots. NVS maintains a standard set of species code abbreviations that correspond to standard scientific plant names from the Ngä Tipu o Aotearoa - New Zealand Plants database.
CYPCON
Referencing and citations
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.
Attribution
Facthsheet prepared by Paul Champion and Deborah Hofstra (NIWA).