Regina's Apple Tree

Regina's Honey Crisp apple tree has been under her care in both Fairytale Land and Storybrooke. She has had it since she was a young girl and boasts of the tree's heartiness. Because Regina tends the tree with care, she is frequently seen having conversations near it. It is first featured in the Pilot episode. As of An Apple Red as Blood, the tree has begun rotting. The tree has been in both Fairytale Land and Storybrooke.

History
In the Pilot episode, Regina is seen tending her apple tree when Sydney brings her a copy of the latest edition of The Daily Mirror, which shows an arrest photo of Emma. Regina later goes to find Emma and offers her some apples, explaining that she picked them from her honey crisp tree and provides some background history on the tree. Henry later warns Emma not to eat apples from Regina's tree, taking the apple from her hand and throwing it.

In The Thing You Love the Most, Emma takes a chainsaw to the tree after getting frustrated with Regina. Regina sees her through the window and comes out, demanding to know what Emma is doing to her tree. After arresting Emma at the mayor's urging, Sheriff Graham goes to talk to Regina and, once again, finds her in the yard tending her damaged tree.

Back in Fairytale Land, during Fruit of the Poisonous Tree, a much younger Queen Regina is living at the palace with King Leopold when he returns one day with the Genie. After finding her by her apple tree, the Genie has an emotional discussion with Regina, who manipulates him into killing the king. The Genie is later shown under Regina's apple tree, getting the box from Regina's father that contained the vipers to kill the king.

The opening scene of An Apple Red as Blood shows Regina tied to her apple tree in the town center, with the putrified apples so rotten that they squish into a black ooze in Emma's hand. After Regina wakes from this nightmare, she notices that her apple tree really is rotting and conftonts Mr. Gold about it being a sign that the curse is breaking.

Trivia

 * The episode title Fruit of the Poisonous Tree alludes to the scenes taking place under the tree during which Regina, the Genie and her father plot to kill King Leopold.
 * The finale of the ABC show GCB references Once Upon A Time through allusion to Regina's apples. Sharon is able to help the police find their kidnapper by identifying the unique "honey crisp apple" the woman was eating, which were rare enough that only one market in the region sold them.
 * The apple tree appears to be symbolically tied to either the power of the Dark Curse or to Regina's magic - the last of which she used to bring her poison apple back from Fairytale Land.
 * The poison apple that Regina uses for the sleeping curse may have originally come from her apple tree when it was in Fairytale Land.