Visual3D Game Engine has built-in support for SpeedTree-like functionality for realistic, high performance vegetation rendering, animation, placement, and procedural forest/world generation, for trees and other vegetation (grass, plants,  flowers, shrubs/bushes, etc.), as well as natural land cover (eg. rocks) and other models.

This is based on our Vegetation and Land Cover rendering system, which includes support for normal and parallax mapping, clustering/procedural forest generation, instanced, cluster-based rendering, and wind animation.

Wind animation  works out-of-box with any tree/plant (or even non-plant, eg. flag) models (avoiding need to animate them using a 3rd party tool). 

We have  automatic (yet still configurable) wind/vegetation animation support which is enabled, for any Model, by setting a Model's ObjectType (through Object Editor or Model Editor) to Plant, Tree, Grass or Bush.  You can select a Model Part in Object Editor and configure additional wind animation settings there, as well as define and reuse Plant Wind/Waving Animation Shader presets, as found under Media/Shaders in Asset Explorer.

We have built-in tools for painting vegetation and other ground cover (rocks, objects, etc.) onto the terrain, as well as painting, sculpting, importing, and generation of terrain, and can also import Land Cover Classification maps, as a number of applications, including geovisualizations, flight simulators, and games, have used in the past for very scalable massive virtual world rendering and generation.
We will have a video tutorial and documentation available soon for Land Cover painting, as its a newer feature available in our latest public release.

Our user base has found this to be effective for their needs, especially since it allows them to avoid $10,000+ in licensing fees per title and platform and avoid the proprietary SpeedTree format and per-vegetation-species licensing fees (where our licenses are both less expensive, and for unlimited royalty-free titles). Considering that, we have had little interest expressed in in we have had very little request for SpeedTree integration.  We also have had built-in support for procedural tree model generation, though haven't tested or updated that recently as we have found very good, inexpensive, powerful and easy to use alternatives to SpeedTree's modeling tool and plant libraries, but without SpeedTree's high, per-title/platform licensing fees, such as

We suggest the following model libraries and procedural modeling/generation tools for trees, plants and vegetation used with Visual3D.

1. XfrogPlants (libraries of both game-ready .obj / .3ds and editable models, $149 for 60 models, or $599 for 360)
2. Xfrog ($299-$399 for standalone modeling tool, includes vegetation library, generate vegetation or procedurally edit XfrogPlant models)
3. Xfrog for Maya or Xfrog for CINEMA 4D ($399, same as Xfrog, except as a plugin for a modeling package)
4. OnyxGarden ($595, includes large library)
5. natFX for 3ds max or Maya ($990, for use with the largest known library of realistic trees/vegetation)
6. T-Gen ($162, and free for non-commercial use),

All of the above options have been found to very competitive alternatives to SpeedTree, when combined with our built-in vegetation rendering and animation systems, placement tools, and procedural forest generation support.  They are not only much less expensive, but also often are much easier to get started with, and in some cases, have larger libraries of game-ready and procedurally editable trees and other vegetation, which can allow trees to be exported to standard formats (as opposed to SpeedTree's proprietary format and runtime licensing/deployment restrictions). 

If there are some cases in which SpeedTree is preferred, please let us know, and we will consider adding it as an option, to accommodate those who may already be familiar with using.

However, the aforementioned tools and packages are royalty-free options which allow use of trees with an unlimited number of game or simulation title (avoiding ~$10,000 per title per platform licensing fees with SpeedTree), so they therefore work well with Visual3D Game Engine's licensing model, for royalty-free use for an unlimited number a titles.