He doesn't know where they're going, but the smell of tree soon answers that question for him. It's not a traditional Christmas tree, if the smell's any indication, but since it's a tree and it's inside, he assumes that it's there because of the holiday. When his fingers touch things that are most definitely not leaves, he thinks his theory has proven true.

"Christmas tree, yeah?" He turns his head in Steve's direction. "Did you help decorate it? Are some of these ornaments Steve Rogers originals?"