From flowers, bushes and fruit trees to dense forest shrubs to dry desert plants, an enormous variety of plants bear prickly thorns. Some plants--such as the rose bush or the Prickly Pear--are admired for their aesthetics in spite of their thorns or spines, while gardeners sometimes shun other thorny plants, like the Devil's Walking Stick. Regardless of the variety, always use caution when planting, harvesting or otherwise interacting with thorny plants.
According to Purdue University's Department of Horticulture and Landscape Architecture, all true varieties of lemon trees (the genus of citrus limon) produce long, sharp thorns on their twigs. These thorns generally bear the greenish color of lemon twigs and can reach up to about 3 inches in length. Lemon trees grow in tropical and subtropical climates, reaching up to 20 feet in height and bearing fragrant yellow fruits as well as dark green oblong leaves and small pale yellow flowers. Genoa, Libson and Florida Rough varieties tend to produce the most thorns. Many varieties of lemon fruit are harvested for their juice, fragrance and oil; harvesters should beware of long thorns capable of painful skin punctures and scratches.
Perhaps just as famous for prickling thorns as they are for beautiful blossoms, diverse rose species produce equally diverse types of thorns. America's national flower, this popular garden plant comes in over 6,000 varieties and blooms from spring until late autumn (according to the Alabama Cooperative Extension System). Rose thorns grow densely on all sides of the stem, often appearing reddish in color and bearing a triangular, fin-like shape and reaching about a centimeter in length. In plentiful direct sunlight, roses bear fragrant flowers in a variety of colors--from white to red to orange. Rose bushes grow up to six feet tall; due to their thorny yet aesthetically pleasing nature, landscapers often employ them as borders, barriers or hedges.
Aptly nicknamed the Devil's Walking Stick, Hercules' Club, Prickly Ash, Pick Tree or Prickly Elder, the aralia spinosa is a spiny tree that grows up to 35 feet tall in forest areas. Plentiful thorns grow on the branches and stems of the trees, as well as on the leaves of young plants. These thorns appear in the same brown color as the tree's stem and form in clusters or spiral patterns; some take short, stubby shapes, while other have thick bases and protrude up to about 4 inches. According to the United States Forest Service and Floridata, this plant begins life with naked stems and pale green leaves clustered on top, but eventually evolves into an almost shrub-like form. Aralia spinosa produce white flowers in the warm months and clusters of purple, mildly toxic berries in the autumn season.