Firethorns are upright or sprawling thorny evergreen shrubs, native to western Asia. They are so popular in the United States that over 30 species and varieties are available. They're grown for their fine foliage and bright berries that last into the winter. Scarlet firethorn (Pyracantha coccinea) is the most commonly grown species.
Size: Firethorn grows as a shrub with an open habit from 6 to 10 feet tall. Trained against a wall it may reach to 20 feet. Un-pruned, it will spread 6 to 10 feet. Low growing versions that serve as groundcovers grow to only 2 or 3 feet at maturity.
Foliage: Firethorn leaves are 1 to 1-1/2 inches long, narrowly oval with smooth edges. They grow alternately along stiff, thorny branches. Although they are deep green above, they are a lighter green underneath. Pyracantha foliage is described as semi-evergreen because in the South leaves stay green over the mild winter. Farther north, as winters grow more severe, firethorn foliage turns brown or purplish. At the northernmost edge of its range, firethorn may lose all of its leaves over the winter.
Flowers and Berries: Firethorn is dotted with clusters of small (1/4-inch diameter) white flowers from April to May. They have an unpleasant scent that does not seem to discourage honeybees. Later, distinctive bright red or orange berries appear in large bunches in the fall and last into January. These berries are attractive to birds, such as starlings, which consume great numbers of them.