A plant noted for its deep, blood-red flowers, from which it took its name: seregon means 'blood of stone'. It was a plant of the same kind known today as 'stonecrop', which grows in low clumps on the face of rocks, and produces bright clusters of flowers.

Seregon was famously the only plant found on the rocky head of Amon Rûdh: when it was in flower, the head of that hill appeared to be bathed in blood. This proved to be ominous, because it was here that Túrin's outlaw band were betrayed to the Orcs by Mîm, and their blood ran among the red flowers of the seregon.