What plants for discus tank?


        I would like to add some plants to one of my discus tanks and
was wondering if some could assists me in making a selection.... This is a
55 gal tank that was set-up about a year ago.  I used Dupla laterite and
about 3 inches of very fine gravel for the substrate.  The tank is lighting
consists of 2 48" 40W bulbs (triton & daylight).  Temperature is 83-84 F, Ph
6.0-6.2, water here is very soft (~3 dKh/ dGh).  I originally planted the
tank with the following plants:

        1) hygrophilla polysperma
        2) hygrophilla siamensis
        3) hygrophilla hybrida
        4) echinodorus rubra
        5) echinodorus cordifolius
        6) echinodorus tenellus
        7) echinodorus paniculatus
        8) valisneria spiralis

The hygrophillas are still doing well and need often trimings.  The amazon
sword (#7) is the only echinodorus left ( cardifolius outgrew the tank and
all others "melted" away as did the valisneria).  The plants that are still
doing well look really nice but I would like to get some variety of plants
to add to what I already have.  If anyone has any suggestions on what plants
may do well in my conditions and where I could get them from, please let me
know.  TIA,

Tom Misiak