Thank you all; the plants were all added about 6 weeks ago, and the tank was already 80 deg F. The only one that didn't get brown was a crypt spiralis, but it didn't grow either so I put it in the 75 gal with two others that are growing beautifully.
So just the lacy java is left, with some dead leaves and some OK ones. I suppose I could turn down the heat in the betta tank, add some new plants, and then slowly raise the temperature back to 80.
I'll take your lists of successful plants to the LFS next time I go, and hope they have some! I'm so ready to be done with plastic plants.