A new competitor to SpeedTree is on the horizon in a tool called “Woody3D”. Fully animated tree generation and rendering with just a click of a button, and it now comes complete with C++ and SDK code to allow you to link it into any application of your choosing. The new version even comes with a free license allowing you to “try before you buy”, really giving you no reason not to at least give it a shot.
If you decide to buy, it’s available for $99 with a license that allows 2 PC’s per seat, and an unlimited number of applications (Although a commercial license is required for apps grossing over $250k)
Hit their website for all the details and downloads.