A fern is a member of a group of vascular plants that reproduce via spores and have neither seeds nor flowers.
They differ from mosses by being vascular, i.e., having certain tissue that conducts water and nutrients, and having branched stems.
Like other vascular plants, ferns have leaves, and these are “megaphylls”, which are more complex than the “microphylls” of clubmosses.
Most ferns are leptosporangiate ferns, sometimes termed “true ferns”; they produce what are called “fiddleheads” that uncoil and expand into fronds.
The group includes about 10,560 known extant species. (source)
Can Guinea Pigs Eat Ferns?
No they can’t at all. They are not nice for them to eat and from my experience they will avoid them.
For more foods that guinea pigs can and can’t eat, check out our guinea pig food list