Related Clues:

• Oak or pine
• It has bark but no bite
• Hierarchical chart
• Squirrels' hangout
• Swing support, perhaps
• It's stuffed with wood
• Cherry or chestnut
• Family diagram
• Cheshire cat's hangout
• Bird house?
• Arboretum specimen
• Shoe saver
• Oxford insert
• See 75-Down
• Conifer