Downloaded and installed the TPF Explorer:

TPF Explorer does not open any of the TPF files that came with The Plant Factory, trying to open them results in "Sorry,the indicated file can not be loaded" after which TPF Explorer shuts down and has the be restarted for a new attempt. 

Created a tree , saved as .TPF , this one could be opened by TPF Explorer. The option to  export to Poser is available in TPF explorer. The Poser export creates an OBJ with MTL file, the textures are PNG and JPG (trunk). Since I don't have Poser installed at the moment I could not try the result in Poser.

Note: I have TPF Designer installed here.