Why are ferns unique?

Dr Patrick Brownsey and Dr Leon Perrie from Te Papa explain why ferns are unique among land plants. Ferns have 2 independent living structures within their life cycle – the sporophyte and the gametophyte.

Point of interest:

• How does the gametophyte of a flowering plant differ from the gametophyte of a fern?

DR PATRICK BROWNSEY

Ferns are unique in land plants in having two separate living structures, so the ferny plant that we see out in the bush produces spores, and those spores, when they are released, don’t grow straight back into a new ferny plant. They grow into a little tiny plant that we call a gametophyte. It’s about half the size of your little fingernail and very hard to find in the bush. That gametophyte and the sporophyte plant, which is the ferny plant, they are 2 independent living parts of the life cycle of the fern and no other land plants have those 2 separate independent living stages.

DR LEON PERRIE

What really separates ferns from the others is that they are – both of the phases, the sporophyte and the gametophyte – are free living. They are not dependent on one another. In the mosses and in the liverworts, the sporophyte is dependent for its food on the gametophyte. In the flowering plants and the other seed plants, the gametophyte is not free living. It’s dependent nutritionally on the sporophyte. Ferns are different because both of them are independent.

Acknowledgement: Museum of New Zealand Te Papa Tongarewa