Its name says it all. Firethorn, Pyracantha coccinea, produces an abundance of fiery red berries on unavoidably thorny stems. A few old fashioned cultivars produce equally fiery orange berries. Cultivars with fiery yellow berries are now rare. Berries ripen for autumn, in time to feed migratory birds. Late berries can last longer after migratory birds are gone.
The rigid and wickedly thorny stems of firethorn work well as impenetrable hedges. They are rather difficult to prune and handle without impalement though. Unfortunately, simple shearing deprives formal hedges of some of their new growth that blooms and fruits most abundantly. Selective pruning is tedious and more hazardous, but might enhance bloom.
Shrubby cultivars of firethorn can grow higher than first floor eaves. Mature and vigorous hedges with hefty interior trunks at such height can generate spirelike growth that almost reaches second floor eaves. With pruning, some cultivars that sprawl close to the ground can stay quite low. Without pruning, some slowly form thickets that are several feet deep.