They're also not very observant. Within this article regarding Washington's plans to plant cherry trees behind the outfield fence at their new ballpark, opening in 2008, team president Stan Kasten is quoted as saying, "We couldn't find another ballpark that had trees in the ballpark." That's kind of a cumbersome way to say what you're trying to get across, Stan, but it also indicates that you must not have looked very hard.
From the "Coors Field A-Z Guide" on rockies.mlb.com: "Trees used are Colorado spruce, pinon pine, bristle cone pine, con color fir, limber pine, gamble oak and curl leaf mahogany." Italics mine!
Stupid Nationals. You totally deserve to have Peter Angelos siphoning off all of your profits for the next twenty years.