In the left corner, downstage, stands the four-foot-high stump of a slender apple tree whose upper trunk and branches lie toppled beside it, fruit still clinging to its branches." (1.1)
This is Larry's tree, built as a memorial when he didn't return from World War II. It's a polarizing fixture of the Kellers' backyard, and a symbol of the complex attachment characters have to Larry's memory. Kate is relieved when lightning strikes it down, a sign that Larry is still alive, that they tried to bury him too soon. At the opening of Act 2, killing time (and burning off some nervous energy) before dinner, Chris chops the remaining trunk down. He wants no reminders of his brother messing up his impending engagement to Ann, his brother's former fiancée.