I have 40 watt
lighting on a 20 gallon aquarium, so I will need low light
plants.

Not necessarily. You have 2 watts per gallon - moderate light, in my book.
You can probably grow most plants with that lighting, especially if you have a
20 long instead of a 20 high. In fact, you probably should include some fast
growers, or you'll have algae problems.

The only thing is, your tank is not very big, so you'll want plants that don't
get too big. I think you may find many Apons eventually get too big for a 20
gallon.

The biggest one has 7 short (about 3-4 inches) leaves and
for some reason it sent up 2 shoots that are about 8-9
inches tall. is that supposed to happen?

Yes. Apons tend to get very, very large. They don't stay 3"-4", I'm afraid.

Java fern, java moss, and anubias are all great for beginners. However,
consider something like wisteria (Hygrophila difformis) as well. With your
lighting level, you can and should grow some faster growing plants as well.


Leigh

http://www.fortunecity.com/lavender/halloween/881/