Wild-spored rockery ferns

Fern-No.4-002-0.jpg Fern-No.4-001-1.jpg Fern-No.4-003-2.jpg

Dear Andrew, Alison,

Can you help me identify some young ferns that have appeared on a tufa rockery in my London garden. The tufa is in full shade, moist & moss covered.

To give you a sense of scale I’ve potted them up into 9cm pots. The largest (Fern no.4 is in a 1 litre pot. So far, it is only no. 4 that has developed indusia.

I upload images of fern 4 with this post