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habit (photo: Biosecurity Queensland)
leaves (photo: Biosecurity Queensland)
stems and leaves (photo: Biosecurity Queensland)
stems and leaves on land (photo: Biosecurity Queensland)
Neptunia oleracea Lour. and Neptunia plena (L.) Benth.
Neptunia oleracea Lour.: Neptunia natans (L.f.) Druce; Mimosa natans L.f.; Neptunia prostrata (Lam.) Baill.; Mimosa prostrataLam.; Mimosa aquatica Pers.
Neptunia plena (L.)Benth.: Mimosa plena L.
Fabaceae: sub-family Mimosoideae (New South Wales)
Leguminosae (South Australia)
Mimosaceae (Queensland, the ACT, Victoria, Tasmania, Western Australia and the Northern Territory)
water Mimosa; water sensitive plant; dead and awake
Mexico, north and south America, widely cultivated and naturalised in Asia
Used as an vegetable in Asia, where it is cultivated mostly from cuttings
Water Mimosa (Neptunia oleracea ) is considered to be naturalised around Brisbane, although under eradication there, and N. plena is considered to be naturalised around Brisbane, Cairns and Darwin, similarly under eradication at site.
Water bodies and riparian zones in the tropics and subtropics
Floating, prostrate or ascending perennial herb sometimes forming dense thickets 2-3m high.
- forms thick floating mats on open water
- floating stems can be inflated with spongy white tissue, rooting at nodes
- leaves are finely divided and may be sensitive to touch
- flowers are yellow, in globose heads 1-2cm across
- pods are grouped and held erect, 2-4cm long and c. 1cm wide
- seeds are 4-8 per pod (N. oleracea) and 8-20 per pod (N. plena)
Stems and Leaves
Stems, leaves and leaflets are nearly hairless, or with some small hairs on leaflet margins. Stems are usually reddish on land, and inflated with white spongy tissue on water, often rooting at leaf nodes. Leaves are twice divided (bipinnate) with 2-4 pinnae per leaf , each with 12-25 leaflets per pinna. The leaves are alternate on the stem, but the pinna and leaflets are in opposite pairs. Neptunia plena has a gland on the petiole between the lowest pair of pinnae (absent in N. oleracea ). The leaflets are oblong, 7-12 mm long and 1.3-2.2 mm wide.
Flowers and Fruit
Flowers are grouped in obovoid to globose heads on erect peduncles 3-20 cm long. Each head has 30-50 flowers. The prominent stamens are yellow. The stamens are gland-tipped in N. plena .
Reproduction and Dispersal
Water Mimosa (Neptunia oleracea and N. plena) readily reproduces by seed or vegetatively from broken stems.
Water Mimosa (Neptunia oleracea and N. plena) poses a serious threat to waterways and wetlands. It forms thick mats that impede drainage, and replace native flora, excluding light and reducing oxygen in waterbodies.
Water Mimosa (Neptunia oleracea and N. plena) is a nitrogen fixer, and can therefore increase nutrients in waterways. The hard seeds are likely to be long-lived.
Water Mimosa (Neptunia oleracea and N. plena ) is declared under legislation in the following states and territories:
Biosecurity Queensland fact sheet http://daff.qld.gov.au
Water Mimosa (Neptunia oleracea and N. plena ) are distinguished from native Neptunia species by the fleshy stems and larger pods ( > 2 cm long).
Common sensitive plant (Mimosa pudica) has pink flowers and hairy stems and pods.
Neptunia oleracea and Neptunia plena are difficult to tell apart if not in fruit: N. oleracea has 4-8 seeds per pod and N. plena has 88-20 seeds per pod. Neptunia plena also has a gland on the petiole between the lowest pair of pinnae, and and apical glands on the stamens althogh these tend to fall off.
Fact sheets are available from Department of Employment, Economic Development and Innovation (DEEDI) service centres and our Customer Service Centre (telephone 13 25 23). Check our website at www.biosecurity.qld.gov.au to ensure you have the latest version of this fact sheet. The control methods referred to in this fact sheet should be used in accordance with the restrictions (federal and state legislation, and local government laws) directly or indirectly related to each control method. These restrictions may prevent the use of one or more of the methods referred to, depending on individual circumstances. While every care is taken to ensure the accuracy of this information, DEEDI does not invite reliance upon it, nor accept responsibility for any loss or damage caused by actions based on it.
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