The terminology applied to the plant forms of annuals and perennials is sometimes different from that applied to trees and shrubs....
David Beaulieu
Creeping phlox picture.
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).