I was given this plant by someone several years ago and stuck it into a planted tank with compost and volcanic rock on top. It has a slight stripe to it and in full sun sometimes goes red but at present it's in a window with only a couple of hours sun daily.
The 60litre tank is unheated now that the fish are gone, and receives no supplemental lighting. I only occasionally add some flourish excel to try and keep the hair algae at bay. Room temperature ranges from 5-25 C.
I wonder if it's a sword but the leaves are a bit small being a maximum of 2 inches in length.
Random planting including Vallisneria. Lots of reflection artifact present.