To access the object, from the create panel select Geometry and then Branches. You will now be able to draw branches in the viewport. By hovering over existing branches you can link branches together. The parameters allow control over the type and style of branch you are creating.

One unusual thing to note is that there are four parameters for radius and twist. The reason for this is that a branch is a patch mesh controlled using a central spline, and as each spline segment has four control points, there are four parameters for the radius and twist at these control points. The amount of taper is a result of the difference in value from the first to the last radius parameter.

Deviation parameters add random variations to the radius and twist parameters. Profile noise moves the patch points to create bumpiness and the blend value smoothes the noise out along the branch. Number of segments controls the number of patches around the branch. And the view steps controls the resolution of the patch.

The small button in the top left of the parameters dialogue allows for picking of parameters from existing branches.