Plants in VectorWorks 2008 have changed a lot. Placing plants has not changed. They are…
Vectorworks Tip #227 – Plant Tool – Placing Multiple Plants by Spacing
Use this mode to place multiple plants. This mode uses the plant spacing from the plant definition, rather than the click, and it places the plants along the path between the clicks. You can draw a line or a polygon and Vectorworks will place the plants along it for you.