Ludwigia glandulosa

Ludwigia glandulosa from North America is a very beautiful water plant. It is slow growing and requires CO2 addition to grow well. Stems becomes 15-40 cm tall and 5-12 cm wide. The leaves turn greener if sufficient light is provided. Used to be sold as Ludwigia perennis.

http://www.tropica.com/en/plants/plantdescription.aspx?pid=035A