I’m making a scene about a street with houses and stuff, and to give it more realism I made a tree using the Lsystem (Which amazed me how good it is). But once I make the tree I don’t know how to export it to the file I’m working on. You know what I mean? I make the tree on the Lsys, I go to the Street file, I tried to pass it through the library import (Shift-F1) but nothing happens. Should I save the new Lsys tree under another name every time I create a new tree? Or if anyone knows other method I would greatly apreciate it. Thanks!!! 
I have been using the same script and had the same problem.
My method, which may be clumsy but works, is that once I have a tree I like, I save it, giving it a new file name using “Save As”.
Later, I create a New [empty] scene, and append in from the tree I made the last two meshes under “OBJECTS”. These might be something like mesh.007 and mesh.008. Then I save that file to be used later.
I do the same basic thing when I use the MAKE HEAD script. Just save everything, then load in the needed meshes later.
Hope this helps.
I do exactly like you
Stefano
Right. Me too, with this modification when making multiple trees…
When I have a tree that I like, I dupe it (Ctrl-D), rename it and move it to the side. After I SAVE AS my blend file, I then have a single blend with a pile of objects that are easily identifiable from the Append dialogue.
What I did before reading your advice was to add a plane to the street scene, use Shift-F1, and the plane turned into the tree repeated the same for the leaves, but I’m going to try your method anyway because it seems that the tree is kind of short.
Thanks again. 