Rubus hispidus aka Running Blackberry

Rubus hispidus, or swamp dewberry, belongs to the rose family. This low, woody shrub is native to eastern North America. Its range spans eastern Canada and much of the eastern United States. It grows in swamps, ditches, fields, and open woods. In North Carolina, it favors the coast and mountains. It is less frequent in the Piedmont.

Its branching stems trail across the ground rather than arch upward. They can reach 8 feet [2.4 metres] in length. Stem tips take root and form new plants. The roots live for years, but each stem lasts two years. Stems bear fruit in their second year, then die. Young stems range from pale green to red. They have soft hairs, bristles, and scattered prickles. Their shape ranges from round to angled. Leaves grow alternately and divide into three toothed leaflets. The upper surfaces are green, smooth, and slightly glossy. The paler undersides may have soft hairs.

White flowers open from April through June. Each has five petals with fine, soft hairs. Many stamens surround the green center of each flower. Bees are the main flower visitors and gather nectar. The plant can also form viable seeds without fertilization. These seeds produce plants that match the parent. The aggregate fruits turn from green to red, then dark purple. They ripen in summer and measure about 0.04 feet [0.012 metres] across. People eat them fresh or cooked, though their taste is sour. Preserves are their main food use.

Swamp dewberry suits partial shade or light filtered through trees. Plants For A Future also reports success in sun. It grows in acidic soil rich in organic matter. It tolerates wet ground and also grows in well-drained loam. Sources record it in both moist and dry wild sites. NC State lists USDA hardiness zones 3 through 7. The plant needs little upkeep and can serve as ground cover. It fits natural areas, woodland gardens, and pond edges.

Birds and mammals eat the fruit, while bees use dead stems for nests. The berries also yield blue to purple dye. Plants For A Future records traditional medicinal uses, not proof of benefit. That source lists no known hazards. The stems' prickles remain a concern when handling plants. Cane borers, leaf beetles, aphids, and other insects may attack it. NC State also lists Fusarium wilt as a possible disease.