Constructor's CommentsOne fun/weird thing about this puzzle is that 1-Across also happens to be a theme entry. That's not usually the case, due to the relatively demanding conventions of crossword construction. I hope it makes for a slightly off-kilter solving experience—appropriate for this slightly off-kilter theme.
Fun fact: In a previous version of the puzzle, PINE TREE was the entry at 68-Across. After a bit of revision, it somehow migrated to 43-Across. The hardy conifer survives again!
Finally, many thanks to David for helping to improve this puzzle substantially from its original incarnation.