Related Clues:

• It has bark with no bite
• Christmas __
• Maple or oak
• Aspen, for one
• Ygdrasil or rowan
• Apple, plum or pear, e.g.
• Yggdrasil, e.g.
• Wack-job
• Koala's hangout
• Genealogist's drawing
• Bolt attachment
• Pre-Christmas buy
• See 57 Across
• Acorn, e.g.
• See 38 Down