Fabaceae

Neptunia plena

Common Names: Water mimosa

Plant Form: Floating or spreading herb. Size: Thickets up to 3 m high. Stem: Hairless, reddish on land, inflated with spongy white material when submerged, often rooting at leaf nodes. Leaves: Twice divided, 12-25 leaflets in groups of 2-4 per leaf, leaflets in opposite pairs but arranged alternately on stem. Close when touched. Flowers: In ball shaped clusters of 30-50 with prominent, gland tipped yellow stamens, smaller when plant is on land. Fruit and Seeds: Oval shaped and brown seeds up to 5 mm long. Habitat: Freshwater swamps, ponds, drainage channels. Distinguishing Features: Glandular stamens distinguish from another Water mimosa species (Neptunia oleracea), but otherwise very similar. Impacts: Reduces water flow, creates habitat for mosquitoes, deoxygenates water killing native fish, outcompetes native vegetation.