Sixteen swamp white oak trees arrived at Ground Zero (World Trade Center site) this morning, nine years after the terrorist attacks on the twin towers. These trees are the first of nearly 400 trees that will be planted at the cobblestone memorial plaza surrounding two big pools built on the footprints of the twin towers. Designers of the memorial envisioned a verdant and quiet space that would bring solace to visitors. The white oak trees were cultivated for 4 years at a nursery in Millstone, New Jersey. White oaks were chosen for their beauty and their ability to withstand the severe weather in Manhattan. An elaborate subterranean irrigation system will water and fertilize the grove.