Possible Clues:

• Doctors who check out head colds, for short
• Tolkien's Treebeard et al
• Sinusitis specialists, briefly
• Fangorn Forest folk
• Foes of the evil Saruman
• Fangorn Forest race
• 'The Lord of the Rings' tree creatures
• Tolkien's Quickbeam et al
• Specialty docs
• Tolkien's tree herders