Can you identify these plants?
 

I do not now what species of aquatic plant this is. I have found it in a lake in southern california, it would be nice if somebody could name it for me. would it be ok if i put these in my tropical aquarium?

Not sure... I think I found the same thing in Alabama at a lake though.

There's a risk of transmitting disease to an aquarium if you move wild-caught plants to the aquarium, so most people won't do it.

If it was me, I'd do it after planting it in moist soil for a while. (ie, grow it emersed)

BTW, here's my pics. Think it's the same thing?
http://i.imm.io/6qp4.jpeg

wow looks alot like the plant I have. I put it in my planted aquarium 2 days ago and the fish seem to be doing fine.

Looks like your plant has a wider stem, but other than that they look quite similiar.
I think yours could be mexican oak-leaf plant.. but it's a wild guess.

Could yours be Ludwigia palustris?