Alternanthera philoxeroides

Alternanthera philoxeroides can thrive in both dry and aquatic environments and is characterized by whitish, papery flowers along its short stalks, irregular, or sprawling hollow stems, and simple and opposite leaf pattern sprouting from its nodes. It produces horizontal stems, otherwise known as stolons, that can sprout up to in length and thanks to its hollow stems, floats easily. This results in large clusters of stem amassing and create dense mats along the surface. Presence of a peduncle is a key trait that distinguishes this species from the sessile inflorescences of Alternanthera sessilis. While seed production has been observed in its native range, there is currently no record of viable A. philoxeroides seeds in the introduced range. The weed's intricate root system can either allow them to hang free in the water to absorb nutrients or directly penetrate the soil/sediment and pull their nutrients from below. == As an invasive species ==

Alternanthera philoxeroides is considered a major threat to ecosystems because of the adverse effects it poses on both aquatic and terrestrial environments, as well as the negative influence it has on society. Impacts on vegetation The presence of this invasive species disrupts the natural flow of water due to the dense mats created by its clusters of stems. These dense mats can affect the natural flow of water that is used in irrigation systems and as well as affect the quality of the water by increasing the sedimentation present in the water. In addition, the dense mats present a challenge for the native wildlife by acting as a barrier between them and natural water sources. Impacts on society Dense mats formed by this species influence the natural flow of water, which can impede various recreational activities, such as boating and fishing. This is a commensal relationship between mosquitoes and A. philoxeroides because mosquitoes receive a breeding ground and the plant gains nothing nor loses anything. The increased population of mosquitoes can bring an increased risk of mosquito-borne diseases in humans. Furthermore, the dense mats produced by A. philoxeroides may not present suitable ecological conditions for native species or humans to thrive off. == Reproduction and dispersal ==

This invasive plant depends solely on vegetative means to reproduce and disperse itself in the area it has invaded and established its roots. In its native geographic range, the species spreads to through means of producing viable seeds; however, it has been observed within its non-native ranges that it rarely produces viable seeds. Human dispersal In effort to eradicate the species by manual means, such as mulching or pulling them out, if not removed efficiently, small stem fragments can be displaced to new areas. Soil movement caused by earthmoving machinery is another example of how humans influence the dispersal of the plant. Natural dispersal In aquatic environments, the A. philoxeroides can easily disperse its fragments by being sucked into the path of the waterways. In terrestrial environments, the small fragments of stems and leaf cuttings can be dispersed through the natural movement of soil caused by erosion. Thus, the geographic range of this invasive species can easily be expanded by any means necessary due to its ability to regenerate from practically nothing. == Methods of control ==

Preventive measures Early detection is the best bet to ensure that the invasive species does not successfully colonize a non-native region because of its ability to regenerate and propagate from small portions of its stem or leaf cuttings. However, when that is not possible, the best that can be done is to limit and control the presence of A. philoxeroides in an area. Alternanthera philoxeroides can only establish itself in shallow waters no deeper than , so one method of control is to erect barriers in shallower areas to limit the amount of suitable space the plant has. Amynothrips andersoni, the alligator weed thrips, and Vogtia malloi, the alligator weed stem borer, have also been released in the United States. These species result in immediate wilting and limit A. philoxeroides reproduction by colonizing its stems.[116th Congress (2019–2020)] on January 23, 2019. ==See also==