Thorns are altered branches or stems covered with pointy, sharp barbs. Thorn bushes can be either deciduous or evergreen shrubs that grow to 1 to 20 feet tall. Thorn bushes have a long history of protection; farmers and gardeners use thorn bushes to keep wildlife away from crops and livestock. Some homeowners plant thorn bushes next to windows and around the property line to deter burglars.
Mysore raspberry (Rubus neveus) is a member of the Rosaceae plant family. This native of Southeast Asia develops into a large bush 10 to 15 feet in height. Mysore raspberry bushes have flexible green stems covered in hooked thorns. The 4- to 8-inch leaves have spines along their underside. Mysore raspberry bushes grow edible sweet black raspberries that turn dark black-purple when ripe. This bush thrives in well-draining soil and requires seasonal pruning.
Rosa ausca "Fair Bianca" is an upright, sturdy deciduous perennial rose. Fair Bianca reaches heights of 3 to 4 feet with a 2-foot spread. The stems of Fair Bianca are narrow with sharp thorns. From spring through summer, Fair Bianca blossoms with large, showy pure white English roses. The double flowers have a saucer formation and a strong scent. Fair Bianca rose bushes have ornamental value in gardens and walkways.
Southern dewberry (Rubus enslenii) is a perennial woody shrub from the Rosaceae family. This Texas native grows in numerous soil types and is found along roadsides, fences and thickets. Southern dewberries are a low-forming bush with thorn-covered stems. The thorns curve backward coupled with red tipped bristles. Southern dewberry bushes have star-shaped hairy leaves with a toothed edge. The fruit of the Southern dewberry is a black berry about 1 inch in diameter. Late spring to early summer the Southern dewberry blooms with white flowers.
Black hawthorn (Crataegus douglasii) is a deciduous thorny bush indigenous to northern and western North America. This compact, upright bush grows up to 30 feet in height, classifying some black hawthorns as small trees. The 1- to 4-inch long leaves of the black hawthorn are simple with an alternate arrangement and an egg shape. The bark of the black hawthorn has a thin appearance with scales, and the twigs have a reddish-brown colour and stiff short thorns. Black hawthorns grow edible dark purple fruit and white flowers with green centres.