| | Re: Is this HOTTONIA PALUSTRIS?
Because of the big number of leaves per whorl, 9 or so, I believe it's rather a Limnophila (sessilis or indica or similar). But let's see how it looks when grown out.
@ryu1: In Hottonia the leaves have a dispersed arrangement on the stem, that means, only 1 leaf per node. Many Myriophyllums, e.g. mattogrossense, and Limnophilas have the leaves in whorls - a number of leaves per node, as in Your plant.