The plant form (growth habit) for the ground cover, creeping phlox, for example, is often termed "cascading." The equivalent term for a shrub that functions as a ground cover would be "broadly spreading" (for instance, for creeping juniper shrubs).
Example of a Cascading Form or "Habit"
The Beautiful Cascades of Creeping Phlox
The terminology applied to the plant forms of annuals and perennials is sometimes different from that applied to trees and shrubs....
Creeping phlox picture.
David Beaulieu