The sacred tree often planted at Shinto shrines is sakaki.
Sakaki is the evergreen species Cleyera japonica, native to warm parts of Japan and other regions of East and South Asia. Its glossy leaves and year-round greenery help explain its association with continuity and sacred space. The Japanese character 榊 combines the elements for “tree” and “divine” or “spirit.”
Sakaki is used in Shinto offerings, especially tamagushi: branches decorated with folded paper streamers called shide. Shrine boundaries have also traditionally been associated with sacred trees and evergreen vegetation. In the Kojiki’s account of Amaterasu’s cave, a sacred sakaki tree from Mount Kagu plays a role in the ritual display used to draw her outside.
A common mix-up is confusing sakaki with cherry, pine, or bamboo. Those plants can have cultural or religious importance in Japan, but sakaki is the canonical answer for the sacred shrine tree in this question.