As per Shiva Purana, offering Aak or Madar flowers to Shiva is considered highly meritorious. It is mentioned in the Shiv Puran that Shiva is pleased immediately and grants boons on offering flowers and leaves of Aak. Therefore it is an important offering to Lord Shiva in Hindu religion.
Aak is described as the manpasand or the favorite flower of Shiva.
Aak is known as Erukku in Malayalam and Tamil, yakka in Kannada, jilledu in Telugu, Akan in Assamese, Akanda in Bengali, Madar in English, Akado in Gujarati, Rui in Marathi and Arakha in Oriya.
The leaves of the plant are used in curing diabetes and obesity.
Paste made from the root of the plant is used to cure skin diseases.
The reason for Aak flowers being the favorite of Shiva is because the milk that drains from Aak leaves is poisonous. It has power to damage the eyesight.
Anything that is poisonous is the favorite of Shiva as he alone can turn poison into Amrut.