symbol

tree or DAG (not cyclic)

hierarchical tree (with matrix and other parameters at each node)

sibling based tree (ply pointers)

the book's scene graph tree (with push/pop for the rendering embedded within the tree nodes) [also does make sence at scene designer level, but more focused on getting the render to work fast]
more dynamic (layer display list)

the VRML tree (mapping a data base)

the active version of VRML

shading tree [could make the calculation faster with caching]

CSG (constructive solid geometry) tree

BSP (binary spatial-partition tree) 'separation planes' painter's algorithm cast into a tree. For the one view point the tree walk describes what to show.
'on events' calling 'objects' and EAI (External Authoring Interface)

the VTK tree and the rendering engine pulling on the code

to look at these trees, think of drawing and modeling a car. The car has a wheel and a steering wheel. Both the steering wheel and the wheel turn together. Within the steering space the wheel also rotates.

now think about doing calculations with a lumpy wheel which also moves the car.

animation uses articulated kinematics
we need inverse kinematics (this is hard) so we have the designer specify some values (key frames) and get the rest of the values by inbetweening