Micranthemum glomeratum, (manatee mudflower, baby tears) is a creeping, aquatic or semi-aquatic plant endemic to swamps, shores of lakes, ponds, and rivers of peninsular Florida. It is popular among aquarium enthusiasts for its attractive appearance and low-maintenance requirements. A wild population was found in May 2023 near a dam connecting to Nu’uanu Stream, Oahu, which appears to be the first record of naturalization anywhere in the world. It is suspected that the plants could have originated from discarded aquarium water or plants. The ability of this plant to spread by stem fragments carried by water, and by seeds in mud attached to waterbirds, suggests that it could be more widely distributed on Nu’uanu Stream and perhaps in other streams or aquatic habitats on the island, but it is unclear what impacts this would have in these environments.
High Risk Traits:
- Grows, and capable of spreading, in regions with tropical climates
- Naturalized on Oahu (Hawaiian Islands)
- Reported to be weedy by aquarium enthusiasts, and designated as a weed in at least one publication, but negative impacts have not been described
- Other Micranthemum species are also reported to be weedy, but with unspecified impacts
- A mat-forming plant that may competed with native or desirable vegetation in aquatic habitats
- Reproduces by seeds and vegetatively by stem fragments
- A fast-growing annual, capable of reaching maturity in one growing season
- Seeds and stem fragments spread by water and through intentional cultivation.
- Suspected of being spread by dumped aquarium plants.
- Seeds are reported to be dispersed by mud stuck to waterbirds.
Low Risk Traits:
- Unarmed (no spines, thorns, or burrs)
- Palatable, if not a preferred forage plant, for browsing animals
- Grows in high light environments (dense shade might inhibit growth or spread)
- Herbicides are reported to be effective at controlling a related species and may be similarly effective on Micranthemum glomeratum.