வாக்குன்னார்

வாக்குன்னார் Indian hemp (Crotalaria juncea)
It is a rapid growing crop that is used for fiber production in Indo-Pakistan, also good for use as a green manure in many tropical and subtropical areas in the world as an organic and nitrogen source.    
Ref: http://www.flowersofindia.in/catalog/slides/Sunn%20Hemp.html 

Flower

Fruit