Many flowering plants commonly used in landscaping bear wicked thorns. Thorned plants create beautiful and effective natural barriers if nurtured as hedges. In the wrong locations--in playgrounds or near entryways and paths--thorned varieties can become troublesome. Clippings left on the ground could injure pets and children. Some thorns could flatten tires on lawn equipment or penetrate the soles of shoes.
The Rosaceae family includes over 100 species of flowering plants, most of which bear prickles or thorns as well as blossoms. Growing the ornamental rose can be a challenge for even the master gardener, but the multiflora rose grows wild in fencerows and thickets across the country. Introduced to the U.S. as rootstock for ornamentals, this wild Japanese rose forms thick natural hedges of sturdy vines bearing clusters of white flowers in spring.
Important to home landscapes in arid regions, cacti are known more for their unique shapes and needles than for their flowers. Varieties grown as indoor container plants sometimes bloom profusely or not at all. The conditions which trigger flowering don't always occur when the plant grows away from its natural habitat. The period of bloom may be short--saguaro cacti bloom in the middle of the night and the flowers close permanently by the afternoon of the next day.
Blackberries and raspberries provide home gardens with easily grown and dependable fruit crops, showing clusters of white flowers in early spring. Many of the sweetest varieties of domesticated brambles include bountiful crops of thorns. Thornless varieties may be less productive as well--sweet thornless cultivars like Navajo won't flourish in all regions. In many areas the Himalayan blackberry grows wild as an invasive weed, forming impenetrable thorny thickets.
Several thorned shrubs grow well as tended hedges, providing security as well as beauty. Hawthorne--a species of rose--grows vigorously with a dependable spring bloom and colorful haws or fruits enjoyed by wildlife. Quince also provides thorny security, flowers and edible pear-like fruit. Though the fruits of barberry--another common hedge plant--are edible, thorns guard the berries so well that few people attempt their harvest.
America's native wild plums bear brittle woody thorns along fruiting stems. Sand plum and wild goose plum sometimes find use as flowering ornamentals but are still more common as wild plants. With some of the most spectacular thorns of any American species, the honey locust tree sprouts tough needles in clusters directly from the trunk as well as branches. Individual thorns vary from four to eight inches in length. Spring blooms provide an important nectar source for honeybees.