An ash blossom is the flower of a Commonwealth plant which grows almost exclusively in heavily irradiated bodies of water. This plant is nearly identical to the melon blossom plant found elsewhere in the Commonwealth, but with ash-colored vines and ash-purple flowers.
Statistically, ash blossoms are identical to melon blossoms, providing the exact same health restoration and radiation penalty. However, ash blossoms are the only plant which grows within the irradiated expanse of the Glowing Sea, and thus are the only viable food option available to the Sole Survivor if they run low on other provisions.
Ash blossoms cannot be purchased or looted from NPCs or containers, and can only be obtained from one source: ash blossom plants. A total of 99 ash blossom plants can be found throughout the Commonwealth.
Two ash blossom plants can be found growing in a small inlet across the river almost due south from Cambridge Polymer Labs. Unlike the plants found in the Glowing Sea, these plants are found growing on the rocks of the shore, rather than in the water itself. These are the only ash blossom plants found outside of the Glowing Sea.