There are three, you have to go all the way to the left of the world and you'll meet a another critter
I think you misunderstand what OC is saying, they said "FxM," meaning female + male (more commonly just F/M or F+M). Though, I only saw 1 M/F scene, I don't think the plant counts.
Oh yeah, mb.. but yeah there are only 1 MxM and 1 MxF... and the plant thing doesnt really count