Possible Clues:

• Source of wood for baseball bats
• Source of tough, straight-grained wood
• Wood source for a baseball bat
• Growth threatened by an emerald borer
• Plant with helicopter seeds
• What Yggdrasil of Norse mythology is
• Where many bats originate
• Theresa Cook is a producer of hurley sticks
• Source of material for a baseball bat
• A short way to get round hardwood supplier