Ezellohar, also called Corollairë, was the green mound in the midst of the Ring of Doom, upon which the Two Trees of Valinor once grew.
Ezellohar was the name of a small hill that was located just outside the western gates of Valimar, the city of the Valar. After Yavanna hallowed it, she sang a powerful song sitting upon the green grass before the Máhanaxar. Of which, she thought of all the things that could grow from the mound. Afterwards, Nienna pondered in silence and watered Ezellohar with her tears. As the other Valar watched, two slender shoots emerged from the mound when the song of Yavanna was the only sound that could be heard. The saplings quickly grew "fair and tall", eventually becoming the Two Trees of Valinor.
Later, Manwë sat with Yavanna upon Ezellohar beneath the Two Trees, informing her of Eru's judgment concerning Ents and Eagles.
During a high feast, Melkor and Ungoliant came before Ezellohar. The Unlight of Ungoliant devoured the roots, while Melkor came onto the mound, slaying the Two Trees with his black spear. The sap of the Two Trees poured like blood upon Ezellohar where Ungoliant sucked it up, before draining the Wells of Varda and covering the green mound in a black vapour.
When the winds of Manwë had cleared away the black vapours, Yavanna came onto Ezellohar, only to find that it had become bare and black. After Fëanor refused to break the Silmarils to restore the Two Trees, Nienna came up onto Ezellohar, threw back her grey hood, and washed away the Ungoliant's defilements of the green mound, mourning the Marring of Arda with a bitter song.