prickly shrub
mesquite
Barberry
Horizontal scrub
Chaparral is a thorny shrub native to North American prairies.
It is a creeping rhizome shrub with branched thorny whitish stem.
Sounds like a Berberis.
An aspalathus is any of the genus Aspalathus of flowering plants, or a thorny shrub yielding a fragrant oil.
A barberry is a thorny shrub of the genus Berberis, which bears yellow flowers and red or blue-black berries.
An andromeda is a shrub of the genus Pieris with small leathery leaves and small flowers. Alternatively, it is another name for bog rosemary.
The Henna plant is an evergreen shrub. It is medium in size and grows 3' to 5' or more. Henna is a slow-growing shurb with dainty, bright green dense foliage.
If you cut a Eucalyptus back to ground level in the spring it will grow as a shrub and show juvenile foliage, let it grow and it will quickly become a tree.