Cyperus congestus
Common name
Purple umbrella sedge
Family
Cyperaceae
Flora category
Vascular – Exotic
Structural class
Sedges
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
Conservation status
Not assessed
Brief 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.
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.
Features
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.
Flowering
Summer to autumn
Flower colours
Green, Red/Pink
Fruiting
Summer to autumn
Life cycle
Seed dispersed by contaminated machinery.
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.
Etymology
cyperus: From the ancient Greek name for sedge, kypeiros
Attribution
Facthsheet prepared by Paul Champion and Deborah Hofstra (NIWA).
References and further reading
Healy, A.J.; Edgar, E. (1980). Flora of New Zealand, Volume III. Adventive Cyperaceous, Petalous and Spathaceous Monocotyledons. Government Printer, Wellington. 220pp.
Champion et al (2012). Freshwater Pests of New Zealand. NIWA publication. http://www.niwa.co.nz/freshwater-and-estuaries/management-tools/identification-guides-and-fact-sheets/freshwater-pest-species
Johnson PN, Brooke PA (1989). Wetland plants in New Zealand. DSIR Field Guide, DSIR Publishing, Wellington. 319pp.