Indigo Milk Cap (Lactarius indigo) is a widespread but uncommon, distinctively colored mushroom. In the summer and fall it can be found on the ground alone, scattered, or in groups, in oak and pine woodlands. It grows on the roots of hardwoods, including oak, ironwood, and blue beech; and pines.
The cap is blue when young, often with concentric rings of darker blue. As it ages the color fades to silvery-blue and it may develop greenish stains. The flesh instantly turns blue when cut and it slowly bleeds blue latex. The flesh and latex eventually turn green with exposure to air.
No other milk cap mushroom “bleeds blue”. This species is further identified by the blue gills.