The 'Dangun myth' tell the story of Korea's origins. Hwanin/Haneullim is the Supreme God, whose son Hwanung descends to earth to a sandalwood tree. His son is Dangun, founder and god-king of Gojoseon, the first Korean kingdom.
The first extant record of the myth is in the Samguk Yusa (Chinese Source Text), the 'Memorabilia of the Three Kingdoms', written in Classical Chinese - the script then used in Korea. From the Haneullim Wikipedia we read:
The prince arrived under the Sindansu/ Shindansu (신단수/ Hanja: 神檀樹, "Holy Tree of Sandalwood") on the holy mountain, where he founded his holy city.
It cites Dr. Lee Chi-Ran, The Emergence of National Religions in Korea, where we see the tree reapear in this line:
However, she lacked a husband, and soon became sad and prayed beneath a Sindansu (신단수; 神檀樹, "Divine Betula") tree to be blessed with a child.
We read elsewhere that the tree is called Paktal Namu, as in Hyung Il Pai's Constructing Korean Origins: A Critical Review of Archaeology, pg. 58, "the old name for the sacred tree tansu (paktal namu)."
Some claim it is the Betula Schmidtii, like Keith Pratt and Richard Rutt in Korea: A Historical and Cultural Dictionary, pg. 481. Birch does feature in Korean shamanism, so much so that it was brought from the North to the South (where it doesn't grow), as recounted here in Are All Warriors Male?: Gender Roles on the Ancient Eurasian Steppe, pg. 121, by Katheryn M. Linduff, Karen S. Rubinson. The Koreans were even called the race of the 'sandalwood', and the tree is considered the Tree of Life in Korean Shamanism, so identifying the correct genus and species should be quite important.