Plant identification

I hope someone could please help me identify this plant. Details as below..

Location: Coimbatore, India
Date of Picture: 29.08.2011
Source: A relative of mine had given this plant saying its leaves has excellent herbal properties.
Mis. info: This plant had grown from the seeds of the mother plant. The plant is grows upto 1.5 Meters high in 3 months. The flowers of this plant are yellow in colour.

Thanks in advance for your help.

 

Maybe... Ludwigia longifolia

 

Thanks for your reply.
However I have found it to be a Barleria Lupulina.