Green spots on plants

I was wondering if anyone could help identify these strange round, green
spots that have started growing on my plants (namely on the hygro).  They are generally 2-3 mm 
in diameter, and are a deep green colour.  Is this a type of strange
green algae, or could this be a plant infection of some sort?  I have
two S.A.Es, but they seem to have no effect on removing these strange
spots.  Any plant leaves that have these green spots on them curl up and 
eventually die off.  My tank is a heavily planted 33 gallon which contains
hygro, wisteria, amazon sword, and cabomba).  I do have some visible algae
growth in my tank (a little on the sides of the tank, and a bit on some rocks).

Any help would be greatly appreciated!