Alternanthera Rosaefolia is a variant of Alternanthera Reineckii aka Scarlet Temple.   This plant is commonly used in Dutch aquascapes for its bright and vibrant red colors.

It is easily characterized by the white vein-like patterns on the leaves.  Like many other stem plants, it requires medium to high light with the addition of CO2 for optimum growth.  It can be grown emersed or submerged and reaches up to 8 inches+ tall