Ferns: How big can a circular sorus be?

I looked at some small ferns under the microscope. The circular sori of the ferns I looked at were less than 2 mm in diameter. The microscope I used had rather weak magnification, so I didn’t get to see lots of detail. Later, I came across an image of large sori Wikipedia:

_{Image source. License: public domain.}

I am surprised by the size of the circular sori in the image. If I could obtain large sori such as these, I would probably be able to see more detail under weak magnification. I’m wondering:

• How big in terms of diameter can circular sori be?

• What are some species of ferns with large sori?