Neptunia oleracea Lour., Fabaceae

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Present on Pacific Islands?  yes

Primarily a threat at high elevations?  no

Risk assessment results:  Risk assessment from the Government of Queensland, Australia (PDF format)

Other Latin names:  Neptunia natans auct.; Neptunia prostrata auct.

Common name(s): [more details]

English: garden puff, water mimosa

Habit:  aquatic herb

Description:  "Aquatic herb with creeping stems usually floating, swollen, and rooting especially at nodes, glabrous or rarely puberulous when young. Leaves very sensitive; stipules obliquely ovate, 5-9 mm. long, 3-5 mm. wide, thin; petiole 2.5-9 cm. long; rhachis 1.1-4.2(-6.5) cm. long; pinnae 2-4 pairs; leaflets 7-22 pairs, oblong, 5-20 mm. long, 1.5-4 mm. wide, basal ones smaller, glabrous or with a few hairs on margins. Flowers yellow, in heads 1.5-2.5 cm. long; peduncles 6.5-23(-30) cm. long. Calyx 1-3 mm. long. Corolla about 3-4 mm. long. Stamens 10; anthers eglandular at apex, even in bud; staminodes up to 17-21 mm. long. Pods bent at an angle to the short basal stipe, shortly oblong, 1.3-2.7(-3.8) cm. long, 1-1.2 cm. wide. Seeds 5-5.5 mm, long and 3-3.5 mm, wide." (Flora of Tropical East Africa [as cited/included in the JStor Global Plants compilation for Neptunia oleracea])

"Aquatic herb. Stems creeping, often swollen and floating, rooting at the nodes. Leaves sensitive, bipinnate with 2-4 pairs. Leaflets in 7-22 pairs, oblong 5-20 mm long, mostly hairless. Flowers in subspherical axillary heads, 1.5-2.5 cm in diameter, bright yellow, on very long peduncles. Pods shortly oblong, up to 1.2 x 3.5 cm, in umbel-like clusters, bent at an angle to a short basal stipe  (Flora of Zimbabwe).

Habitat/ecology:  "In and around pools, lakes and swamps"  (Flora of Zimbabwe).  "Water mimosa takes root on the banks of watercourses and grows out over the water surface, forming floating rafts. Within its native range, water mimosa is a common floating plant in freshwater pools, swamps and canals at low altitudes of up to 300 m. When water levels fall during the dry season, the plants often perish. The plants prefer slow-moving water 30-80 cm deep, full sun and hot, humid conditions. Shade, brackish water and saline soil adversely affect plant growth. Under favourable conditions, water mimosa grows out from the banks to form floating rafts of dense interwoven stems. These can be dislodged by water movement (especially during floods) and are soon replaced by more water mimosa. These floating rafts can: restrict water flow in creeks, channels and drains, impede recreational water sports and boating access, increase water loss through evapotranspiration, reduce water quality by preventing light penetration  and reducing oxygenation of water, create a favourable habitat for mosquitoes, reduce fish activity, cause the death of native, submerged water plants and fish and replace native wetland plants" (Fact sheet on Neptunia oleracea and Neptunia plena from the Queensland Government).

Propagation:  Seed and plant pieces carried by water (Fact sheet on Neptunia oleracea and Neptunia plena from the Queensland Government).

Native range:  "Native to tropical Asia, Africa and South America. It grows wild and is cultivated as a vegetable throughout South-East Asia, particularly Thailand and Indo-China"  (Fact sheet on Neptunia oleracea and Neptunia plena from the Queensland Government).

Presence:

Pacific
Country/Terr./St. & Island group	Location	Cited status & Cited as invasive & Cited as cultivated & Cited as aboriginal introduction?	Reference & Comments
State of Hawaii Hawaiian Islands	O‘ahu Island		Bishop Museum (U.S.A. Hawaii. Honolulu.) (1997) (voucher ID: BISH 649184) Taxon name on voucher: Neptunia oleracea Lour.
Philippines Philippine Islands	Philippine Islands	native	U.S. Dept. Agr., Agr. Res. Serv. (2013)
Philippines Philippine Islands	Philippine Islands		Merrill, Elmer D. (1923) (p. 251) In shallow lakes and swamps at low altitudes.

Pacific Rim
Country/Terr./St. & Island group	Location	Cited status & Cited as invasive & Cited as cultivated & Cited as aboriginal introduction?	Reference & Comments
Australia Australia (continental)	Queensland	introduced invasive	Queensland [Australia] Government (2009)
Cambodia Cambodia	Cambodia (Kingdom of)	native	U.S. Dept. Agr., Agr. Res. Serv. (2013)
Central America Central America (Pacific rim)	El Salvador (Republic of)	native	U.S. Dept. Agr., Agr. Res. Serv. (2013)
Central America Central America (Pacific rim)	Guatemala (Republic of)	native	U.S. Dept. Agr., Agr. Res. Serv. (2013)
Central America Central America (Pacific rim)	Honduras (Republic of)	native	U.S. Dept. Agr., Agr. Res. Serv. (2013)
Central America Central America (Pacific rim)	Nicaragua (Republic of)	native	ILDIS Co-ordinating Centre (2013)
Central America Central America (Pacific rim)	Panama (Republic of)	native	ILDIS Co-ordinating Centre (2013)
Indonesia Indonesia	Indonesia (Republic of)	native	ILDIS Co-ordinating Centre (2013)
Malaysia Malaysia	Malaysia (country of)	native	U.S. Dept. Agr., Agr. Res. Serv. (2013)
Mexico Mexico	Mexico (United Mexican States)	native	U.S. Dept. Agr., Agr. Res. Serv. (2013)
Singapore Singapore	Singapore (Republic of)	introduced invasive	Chong, Kwek Yan/Tan, Hugh T. W./Corlett, Richard T. (2009) (p. 63) Naturalised
South America (Pacific rim) South America (Pacific rim)	Colombia	native	U.S. Dept. Agr., Agr. Res. Serv. (2013)
South America (Pacific rim) South America (Pacific rim)	Ecuador (Republic of) (continental)	native	U.S. Dept. Agr., Agr. Res. Serv. (2013)
South America (Pacific rim) South America (Pacific rim)	Perú (Republic of)	native	U.S. Dept. Agr., Agr. Res. Serv. (2013)
Thailand Thailand	Thailand (Kingdom of)	native	U.S. Dept. Agr., Agr. Res. Serv. (2013)
Vietnam Vietnam	Vietnam (Socialist Republic of)	native	U.S. Dept. Agr., Agr. Res. Serv. (2013)

Indian Ocean
Country/Terr./St. & Island group	Location	Cited status & Cited as invasive & Cited as cultivated & Cited as aboriginal introduction?	Reference & Comments
India (Indian Ocean offshore islands) Andaman Islands	Andaman Islands	native	ILDIS Co-ordinating Centre (2013)
India (Indian Ocean offshore islands) Nicobar Islands	Nicobar Islands	native	ILDIS Co-ordinating Centre (2013)
Maldives Maldive Islands	Maldive Islands	native	U.S. Dept. Agr., Agr. Res. Serv. (2013)
Mauritius Mautitius Islands (Mauritius and Rodrigues)	Mauritius Island	introduced	ILDIS Co-ordinating Centre (2013)

Control: 

Physical:  "There are no chemicals registered specifically for use against water mimosa. In most instances, the most appropriate method of control is to physically remove the infestation. This can be done by removing all plant matter from the infested water body and pulling plants out of the surrounding banks, ensuring removal of the attached root system. This should be repeated on a regular basis until regrowth ceases. All removed plant parts should then be disposed of in an appropriate waste facility or rubbish bin" (Fact sheet on Neptunia oleracea and Neptunia plena from the Queensland Government).