American burnweed, also known as fireweed or Erechtites hieraciifolius, is not considered toxic to rabbits. However, it is not a preferred food for rabbits and may cause digestive upset if consumed in large quantities.

It's always a good idea to introduce new foods to rabbits slowly and in small quantities to monitor for any adverse reactions. Additionally, rabbits require a balanced diet that includes hay, fresh vegetables, and a limited amount of pellets. It's important to provide your rabbit with a varied diet to ensure they receive all the nutrients they need to maintain good health.