Germacranolides are a group of natural chemical compounds classified as

sesquiterpene lactone Sesquiterpene lactones (SLs) are a class of sesquiterpenoids that contain a lactone ring. They are most often found in plants of the family Asteraceae (daisies, asters). Other plant families with SLs are Umbelliferae (celery, parsley, carrots) ...

s. They are found in a variety of plant sources.

References

Sesquiterpene lactones Oxygen heterocycles {{organic-chemistry-stub