Alligator Weed, or Alternanthera philoxeroides, is native to South America, and its dense mat-like coverage can cause considerable problems along shorelines. The perennial plant grows on dry ground as well as in water in which it has a creeping behavior with a stem growing up to 4 feet in length. The sprawling plant has a pinkish stem, either singular or branched. The stem can become hollow with age. The elliptic leaves appear opposite growing to 3.5 inches long with a few teeth along the margin. Roots typically form at the leaf nodes. The aquatic plant produces small fragrant flowers about 1/2 inch in diameter. Each flower produces a single seed.
