Please, could someone tell what kind of fern this is.

It looks very much like Pteris vittata to me..
Ladder Brake Fern (Pteris vittata)
https://www.google.be/search?q...

@bonitin
Thank you for i.d.!

You're very welcome Rainbow!

I thank you also, Myriam! I've been hoping to ID this fern that spontaneously planted itself beside my little pond for a while. That long terminal leaflet on the frond is very distinctive on the Ladder Brake fern, isn't it?

dyzzypyxxy said:That long terminal leaflet on the frond is very distinctive on the Ladder Brake fern, isn't it?

yes, it is Elaine!

I only discovered today we have a fern forum! That's great, I have always loved ferns, they have something mysterious about them..
I recognized Rainbow's fern ( which is also yours according to your picture) because I had met them in Brazil on one of my trips to there.

I have a bunch of Brazilian Atlantic Forest ferns I still have to find an ID for... difficult job and very time consuming..

I have been thinking that it would be good to have a basic picture key just to recognize the different families according to the patterns of the sori on the back of the fronds..

bonitin said:
I have a bunch of Brazilian Atlantic Forest ferns I still have to find an ID for... difficult job and very time consuming..

I have been thinking that it would be good to have a basic picture key just to recognize the different families according to the patterns of the sori on the back of the fronds..

That would be nice. I have different kinds of ferns that grow sporadically around here. They do propagate from spores, right?

@dyzzypyxxy Elaine, there are apparently a few Pteris (Brake Ferns) found in Florida: http://www.florida.plantatlas.... but P. vittata seems widespread and is listed as a Category II invasive in Florida: http://florida.plantatlas.usf....

I think P. vittata might be the one growing behind my deck and also in a neighbors yard.

Hm, much as I dislike the idea of growing an invasive fern, this one has only appeared in one spot in my garden, and is quite small and well-behaved. If I see it propagating itself elsewhere in the garden I'll sure pull it out, but I really kind of like it where it is, growing out of the stones on the fake waterfall of my pond.

I wonder if it doesn't like the high pH well water that the rest of the garden is irrigated with, in the dry seasons (if we ever get a dry season again . . . ) If that's the case, well it's not going anywhere from where it's situated right now.

I haven't had issues with it taking over here in the 4 years we've been in this house, it's actually stayed in the one spot behind our deck and they don't seem to spread at my neighbors house either. Maybe ours is a different Pteris than the P. vittata which is said to be invasive here in Florida.

Then again . . . we don't exactly know how far a fern's spores can travel, do we. Argghh. It's a compelling question! Do we keep it and take the chance or do we get rid of a pretty plant in a nice spot . .. ?