Recognized as a distinct species in the USDA 'Plants Database' https://plants.usda.gov/core/profile?symbol=RUFR4, 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: Yankee Blackberry

General Information

Rubus frondosus is a deciduous shrub producing each year a cluster of vigorous, arching, prickly, biennial stems from a woody rootstock; the stems can be 250cm or more 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 stem tips often arch to the ground where they root and form new plants - producing a dense, impenetrable thicket in the wild[].
The plant is commonly harvested from the wild for local use as a food, and also has medicinal properties. It has been cultivated in the USA since the late 19th century and is a parent of several cultivars[].

Known Hazards

None known

Botanical References

,

Range

Eastern N. America - Ontario to Maine, south to Oklahoma and Georgia

Habitat

Thickets and borders of woods[]. Mainly found in dry soils[]. Woodlands, savannahs, prairies, fields, meadows, swamps, rock outcrops, sand dunes, sandy soil, disturbed areasl; at elevations from 1,400 metres[].

Properties

Edibility Rating
Medicinal Rating
Other Uses Rating
Habit	Deciduous Shrub
Height	0.80 m
Pollinators	Apomictic
Self-fertile	Yes
Cultivation Status	Cultivated, Wild

Cultivation Details

Easily grown in a good well-drained loamy soil in sun or semi-shade[, , ].
This species has been cultivated in the USA since the late 19th century and is a parent of several cultivars - a crossing with Rubus allegheniensis led to the successful blackberry cultivar 'Lawton' (Lawton blackberry), whilst other cultivars have been produced by crossings with Rubus pergratus[].
The plant produces apomictic flowers, these produce fruit and viable seed without fertilization, each seedling is a genetic copy of the parent[].
Plants in this genus are notably susceptible to honey fungus[].

Edible Uses

Fruit - raw or cooked[, , , , ]. The berries have been cooked, shaped into little cakes and then dried for winter use[]. The black, globose to cylindrical fruit is around 10 - 20mm in diameter[].

Medicinal

A decoction of the root has been used to restore the menstrual flow and to treat lung problems[].

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

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[].