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Egeria densa

Dense Waterweed

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Image:	Flower and leaves	53KB

General Information

COMMON NAMES: Dense Waterweed, Waterweed, Ditch Moss, Water Thyme

GLOBAL DISTRIBUTION: NATIVE subtropical South America

COOK ISLANDS STATUS: Introduced - Recent, Sparingly Naturalised; Freshwater, ponds

KEY FEATURES: Submerged herb with whorled densely-packed leaves; unisexual flowers, above the water, with 3 white petals. Naturalised in pools and ponds, and commonly used in aquaria. Native of South America.

Cook Islands Distribution

View Distribution Map

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

Northern Group:
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

Egeria densa Planch.
SYNONYMS: Elodea densa

TAXONOMY: PLANTAE; ANTHOPHYTA (=Angiospermae); LILIOPSIDA (=Monocotyledones); ALISMATIDAE; Hydrocharitales; HYDROCHARITACEAE

More Information

IDENTIFICATION: Branching submerged herb. LEAVES dense-packed, whorled, recurved, oblong, to 3cmx5mm. FLOWERS petals 3 white wide-oval 1cm, unisexual; MALE 9-10 stamens, yellow; FEMALE 3 sterile stamens. FRUIT ~8mm long.

Vouchers & References

Vouchers:
Rarotonga: fieldspeicmen+Photo, Marie Melvin, 8/2001, ID GMcC.

References:
p.1443 Wagner et al.- Flowering Plants of Hawaii
p.58 Neal - In Gardens of Hawaii
p.421 Hortus 3rd
p.410 Royal Hort. Soc. Index of Garden Plants

Data Update History (information):
zTX, zB02, zM02, zD02

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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