About the _D. adelae_, if its the one from me theleaf may have gotten damaged
(cold, etc) during transit. Just clip off the leaf to avoid fungus growth on
the dying tissue. Even if the main plant died there is a good chance of new
plants forming from the roots. As far as the seeds go, the same thing
happened to my windowsill collection, I believe I've heard the term "snow mold"
applied to this critter. After I gave the pot more air (like you've done) the
mold dropped back and seeds germinated just fine (_D. peltata_). So hang in
there! Oh, the germination time was 6 weeks. I actually think the fungus
arrived with the seeds.
Warming mats seem pricey to me. I've been using the top of my TV, refrig., and
fluorescent light ballasts. But be very careful of leaky trays! For lights I
just picked up two 2 bulb flourescent shop lights at Home Quarters Warehouse
for $7.60 US each (some overstock, but maybe this is a national thing?). I use
these to supplement window light. Later.
Jeff in NC
(where its slush)