Recognized as a distinct species in the USDA 'Plants Database' https://plants.usda.gov/core/profile?symbol=RUAR2, this species is treated as a synonym of Rubus pensilvanicus Poir., in the Flora of N. America[].
The genus Rubus, (especially the blackberries, which are often loosely referred to as Rubus fruticosus agg.) presents some of the most difficult taxonomic problems. This is partly due to the frequency of polyploidy; also to the frequent occurrence of hybridization; and also due to apomixis, where minor differences between plants are preserved because seedlings are genetically identical to their parent. As a result, differences of opinion on the number of species to be recognized from a given region can vary tremendously (for example, a treatment by M. L. Fernald[] in 1950 recognized 205 species for the northern half of the eastern United States plus parts of southeastern Canada, whilst H. A. Gleason and A. Cronquist in 1991 recognized only 25)[]. Where possible, a relatively conservative approach is taken here[].

Common Name: Highbush Blackberry

General Information

Rubus argutus is a deciduous shrub producing each year a cluster of erect to arching, prickly, biennial stems from a woody rootstock; the stems can be 100 - 300cm long. The stems only produce leaves, and do not flower, in their first year of growth, forming flowering branches in their second year and then dying after fruiting. The plant can spread rapidly to form thickets.
The plant is commonly harvested from the wild for use as a food and a medicine. It is sometimes cultivated for its fruit in N. America, where it is a parent of several cultivars[, , , ]. It can be used within its native range to stabilize soils and restore native woodland.
Rubus argutus has been declared a noxious terrestrial weed in various countries, including New Zealand and Japan - in Hawaii it is listed among the 12 most significant environmental weeds It is capable of spreading both via seed and vegetative growth and competes with native vegetation. It spreads most rapidly with disturbance; seedling emergence is stimulated by soil disturbance and vegetative growth is much more rapid if the canopy is removed. Even when above-ground shoots are killed by cutting or spraying, it may re-sprout from well-developed roots. While it is effective in recolonizing areas with a moderate or opened canopy, growth of the plant is inhibited by deep shade[].

Known Hazards

None known

Botanical References

,

Range

Eastern N. America - Massachusetts to Virginia.

Habitat

Dry or moist thickets and woodland margins[]. Woodlands, savannahs, prairies, fields, meadows, swamps, rock outcrops, sand dunes, sandy soil, disturbed areas, dry to wet soil; at elevations up to 1,400 metres[]

Properties

Weed Potential	Yes
Edibility Rating
Medicinal Rating
Other Uses Rating
Habit	Deciduous Shrub
Height	2.50 m
Pollinators	Insects
Self-fertile	No
Cultivation Status	Cultivated, Wild

Cultivation Details

Rubus argutus grows best in a warm temperate climate with mild winters and no distinct dry season. It is tolerant of continental climates with hot summers and cold winters and also of more tropical climates, so long as there is rainfall all year round[]. It can tolerate moderate frosts, with some provenances of the plant perhaps surviving occasional falls to as low as -25°c for short periods[].
Easily grown in a good well-drained loamy soil in sun or semi-shade[, , ]. The plant is adapted to a broad range of soil textures. It grows best in full or partial sun but under drier conditions can become desiccated. Habitats ranging from wet to mesic are suitable), including boggy sites. Its drought tolerance is only moderate and it does not tolerate salinity[].
Plants in this genus are notably susceptible to honey fungus[].
This species is occasionally cultivated for its edible fruit in N. America, and is a parent of many cultivated forms[[, , ].
Rubus louisianus (generally considered to be a synonym of this species) is probably the wild form of the cultivar 'Crystal White blackberry' which in the USA is locally (e.g. Illinois) grown for its fruits[].

Edible Uses

Fruit - raw or cooked[, , , ]. Variable in size and quality but generally with rather large and juicy drupelets[]. The pulpy fruit is up to 25mm long[]. Some forms have white fruits[].

Medicinal

The roots are antihaemorrhoidal, antirheumatic, astringent, stimulant and tonic[]. An infusion can be used in the treatment of venereal disease and as a wash in the treatment of piles[].

An infusion of the roots or leaves can be used in the treatment of diarrhoea and rheumatism[].

Agroforestry Uses:

Most, if not all, thicket-forming species of Rubus have good erosion control value. They usually grow satisfactorily on barren and infertile soils and invade and occupy eroded areas. They also establish quickly on burns, old fields, and logged areas. Forming extensive and nearly impenetrable thickets, they can provide excellent cover for wildlife as well as nesting sites for small birds. They are often natural pioneer species, paving the way for woodlands to develop, but they should only really be used within their native range in order to avoid any risks of them invading other habitats[, ].

Other Uses

This species is useful in blackberry breeding programmes, where it can be used to produce cultivars with erect growth. Among others, it has produced the successful cultivar 'Early Harvest'[].

A purple to dull blue dye is obtained from the fruit[].

Propagation

Seed - requires stratification and is best sown in early autumn in a cold frame. Stored seed requires one month stratification at about 3°c and is best sown as early as possible in the year. Prick out the seedlings when they are large enough to handle and grow on in a cold frame. Plant them out into their permanent positions in late spring of the following year.
Cuttings of half-ripe wood, mid summer in a frame[].
Tip layering in July. Plant out in autumn.
Division in early spring or just before leaf-fall in the autumn[].