Nísimaldar (the "Fragrant Trees") was the name given to the area in Númenor surrounding the city and haven of Eldalondë.

In Nísimaldar grew thick groves of many beautiful evergreen trees, brought there as gifts by the elves of Tol Eressëa, and bearing wonderfully fragrant flowers and fruits.

Many of the trees could be found elsewhere on Númenor, although not in such thick groves, but Nísimaldar was the only place wher the famed Mallorn could be found. It was from fruits from the mallorns of Nísimaldar, that the Lady Galadriel grew the famed groves of Lothlórien.
Encyclopedia entry originally written by PotbellyHairyfoot