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Cyperus difformis

One-arm Sedge

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Image:	Plant and detail of flower head	56KB

General Information

COMMON NAMES: One-arm Sedge

TRADITIONAL NAMES: Vayavaya (PK)

GLOBAL DISTRIBUTION: NATIVE Eurasia - China - Malesia - Australia - ?w.Melanesia

COOK ISLANDS STATUS: Introduced - Recent, Naturalised; Land, lowlands, wetlands

KEY FEATURES: Clumped annual sedge to 60cm. STEM 3-angled. LEAVES BASALlimp and shorter than stem. LEAVES TERMINAL 2-3, to 25cm. INFLOR 3-9 main rays to 4cm, w/wo sub-rays with spikelet clusters 5-15mmØ; spikelets flattened, 2-8mm long with 10-30 scales, stemens 1-2, stigmas 1 (one). NUT 3-angles, 1mm long, glossy yellow or pale brown.

Cook Islands Distribution

View Distribution Map

Southern Group: Present Makatea: Present
RR	MG	AT	MK	MT	AK	PL	TK	MN
	P		++			++?		-

Northern Group: Present
TN	MH	RK	PK	NS	SW
-	?	?	+++	?	-

Key to Symbols

blank	no data
-	absent	L	localised
X	extinct 'naturally'	W	widespread
XQi	quarantine intercepted	R	recent
XQe	eradicated	?	query preceding category
P	present	T?	taxonomic query
S	seasonal	nn	present, said to have no name
O	occasional	?1	present, name not investigated
++++	very common	?2	presence not verified, no name recorded
+++	common	N/A	absent, name not expected
++	uncommon
+	rare
Cook Islands islands: RR =Rarotonga, MG = Mangaia, AT =‘Ātiu, MK=Ma‘uke, MT=Miti‘āro, AK=Aitutaki, PL=Palmerston, PN=Penrhyn, MN=Manuae, TK=Takūtea, TN=Tongareva (TS=Tongaleva Spoken, TW=Tongareva Written, they say "el" but write "r"), MH=Manihiki, RK=Rakahanga, PK=Pukapuka, NS=Nassau, SW=Suwarrow. After a Polynesian name: ^=orthography query. Countries and other: FIJ=Fiji, WT=Wallis & Futuna, SAM=Samoa, TON=Tonga, NIU=Niue, CK=Cook Islands, CKM=Cook Islands Māori, FP=French Polynesia, AUS=Australs, SOC=Societies, TAH=Tahiti, TUA=Tuamotus, MQS=Marquesas, MNG=Mangareva, PIT=Pitcain group, EAS=Easter Island, HAW=Hawai‘i, NZ=New Zealand, NZM=New Zealand Māori

Scientific Taxonomy

Cyperus difformis Linnaeus
TAXONOMY: PLANTAE; ANTHOPHYTA (=Angiospermae); LILIOPSIDA (=Monocotyledones); COMMELINIDAE; Cyperales; CYPERACEAE

Vouchers & References

Vouchers:
Pukapuka: fieldspecimen, 2/2004, G.McCormack with ID as Cyperus difformis.

References:
p.1395 Wagner et al.- Flowering Plants of Hawaii
p.1/251 A.C.Smith - Flora Vitiensis Nova

Data Update History (information):
zTX, zB02, zM02, zupM05a

Web Resources

Citation Information

McCormack, Gerald (2007) Cook Islands Biodiversity Database, Version 2007.2. Cook Islands Natural Heritage Trust, Rarotonga. Online at http://cookislands.bishopmuseum.org.
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