A few years ago, I began researching the rules and regulations of wooden bats used in Major League Baseball, MLB. With all the shattered baseball bats in recent years (blasting players and spectators), I began thinking about possible reasons for all the broken bats. The traditional species of wood used in baseball bats was Ash, a ring porous hardwood (similar to oak or hickory) specifically white Ash. I hypothesized that it was diffuse porous woods, such as Sugar Maple (acer saccharum) that was the main culprit.
And http://www.woodbat.org agrees, stating that- in the early 90's, bat manufacturers began using maple more often, likely because A. saccharum' physical properties are 5-10% > Ash.
MLB Official Rules:
(a) The bat shall be a smooth, round stick not more than 23/4 inches in diameter at the thickest part and not more than 42 inches in length. The bat shall be one piece of solid wood.
NOTE: No laminated or experimental bats shall be used in a professional game (either championship season or exhibition games) until the manufacturer has secured approval from the Rules Committee of his design and methods of manufacture.
(b) Cupped Bats. An indentation in the end of the bat up to one inch in depth is permitted and may be no wider than two inches and no less than one inch in diameter. The indentation must be curved with no foreign substance added.
(c) The bat handle, for not more than 18 inches from its end, may be covered or treated with any material or substance to improve the grip. Any such material or substance, which extends past the 18 inch limitation, shall cause the bat to be removed from the game.
NOTE: If the umpire discovers that the bat does not conform to (c) above until a time during or after which the bat has been used in play, it shall not be grounds for declaring the batter out, or ejected from the game.
(d) No colored bat may be used in a professional game unless approved by the Rules Committee.
What struck me when looking over the rules above /\ was what wasn't there- wood species. It's my feeling that not specifying wood species is important as size and weight regulations for Major League Baseball bats.
Here is a good article from NYTimes that I just found (from 2008) http://www.nytimes.com/2008/07/25/sports/baseball/25maple.html?_r=0.