You might try the Swap'n'shop here, Aquabid, or Aquariumplants.com for Marsilia spp. You might also want to get into liquid ferts (I use Seachem's line) and DIY CO2. That'll make your plants really take off. Those swords have emersed leaves. These will die back as new ones (that can survive underwater) grown in. Leave the runners on as these will produce new plants. The best of luck to you!
"One day...one day, this path will lead us to the White City, and the tower guard will take up the call: the Lords of Gondor have returned!"
–Boromir, The Lord Of The Rings