daizeUK said:
A bit of googling turns up Fittonia as a possible culprit? They have white and red veined varieties that look similar to yours.
Think daize is absolutely correct, it does seem to be Fittonia which is definitely a houseplant.
http/houseplants.about.com/od/More_Plant_Profiles/p/Fittonia-How-To-Grow-Fittonia-Houseplants.htm
I fell into this trap too when i first bought plants for my tank when I was setting up my first tank, I bought Draconias even though was in well known LFS and plants were submerged in water!
I've since then took out the plants and repotted them, they are growing and doing fine!
The danger of leaving houseplants fully submerged, more often than not, will die within 6 months then plant roots and leaves will rot, giving the possibility of ammonia spike......
Best to take them out now really, am afraid, maybe you can get a refund or swap for proper aquatic plants if you ask nicely.
And yes, I hate when LFS do this, but this is not usually down to the LFS staff really so don't have a go at them, more like at management level or above trying to get more profits.
Now have learned my lesson! research, research, research before buying anything live for your tanks.
Best that you learned this now, a small price to pay really, as you have learned a pretty valuable lesson, do not take any of LFS advice or stocking at face value.