Alternanthera philoxeroides, commonly known as alligator weed, is a perennial herb native to freshwater ecosystems, riverbanks, and wetlands in South America. It has become invasive in over 30 countries, including the U.S., Japan, and Australia, where it forms dense mats on the surface of water bodies and along shorelines, disrupting water flow and outcompeting native flora. This plant is highly adaptable, capable of growing in both aquatic and terrestrial environments.

Alligator weed is not typically cultivated due to its invasive nature and the ecological damage it can cause. It is characterized by its sprawling habit, small white flowers, and bright green leaves, which can be attractive but are rarely seen in a controlled garden setting. In regions where it is not invasive, it may be used for ornamental purposes or erosion control. However, its aggressive growth requires constant management to prevent it from overwhelming other plants. Alligator weed prefers full sun to part shade, and it thrives in a variety of soil types, provided they are moist or even saturated. It is important to note that Alternanthera philoxeroides is subject to strict control measures in many regions due to its potential to harm local ecosystems.CC BY-SA 4.0