Alternanthera rosaefolia

Family Amaranthaceae, it is also a fairly difficult plant to maintain in a tank, even though it is a fast growing plant. However, it is a very worth while plant to have because of its good colour if grown well. It can be propagated easily by seed or cuttings. Seeds prefer to be grown emersed while cuttings can be cut and planted directly into the tank substrate. Apparently plants grown from seed adapt more easily to the aquarium environment than plants grown from cuttings, but given good light and ample micronutrients both do well. CO2 does help considerably

http://www.aquariumplants.co.za