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: Thimbleberry

General Information

Rubus parviflorus is a deciduous shrub, forming a cluster of erect, unarmed, biennial stems 50 - 300cm tall from a woody rootstock, The plant forms an extensive underground rhizome system from which it vigorously sprouts, spreading to form dense thickets of growth[, ].
The plant is harvested from the wild for local use as a food, medicine and source of materials. It is occasionally grown as a fruit crop and can be used within its native range to stabilize soil. It is often grown as an ornamental, where it can be used as a tall ground cover for large areas.
The plant is cultivated, mainly as an ornamental, in various temperate countries. It has escaped from cultivation in parts of Europe and Australia, where it has become naturalized and invasive. There is concern that the regeneration of conifers in clear-felled areas can be prevented because Rubus parvifolius can quickly form dense monocultures in such conditions[].

Known Hazards

None known

Botanical References

, ,

Range

N. America - Alaska to Alberta and Montana, south to California and New Mexico; Ontario, south to South Dakota, Illinois, Michigan

Habitat

Woodlands, canyons and open areas[]. Moist areas, open woods, thickets, clearings, stream banks, canyons, grassy meadows, rocky cliffs, sand dunes, upper beaches, dry sandy areas, roadsides; at elevations up to 3,000 metres[].

Properties

Weed Potential	Yes
Edibility Rating
Medicinal Rating
Other Uses Rating
Habit	Deciduous Shrub
Height	2.50 m
Growth Rate	Medium
Pollinators	Insects
Cultivation Status	Cultivated, Ornamental, Wild

Cultivation Details

Rubus parviflorus has a very wide environmental tolerance, being found from Alaska to as far south as California and New Mexico (usually at higher elevations in the south). It can tolerate considerable frost, succeeding in cold continental climates, and also grow well in warm temperate climates. It is able to tolerate dry summers[], though fruit quality suffers[].
Easily grown in a good well-drained loamy soil in sun or semi-shade[, , ]. Can be grown in a woodland garden though it is less likely to fruit well in such a position[].
If flowers and fruit production are a priority, consider pruning as follows:
(1) Remove canes that have fruited immediately after fruit is harvested, leaving the new vegetative (non-fruiting) canes to overwinter. Also remove at this time any non-fruiting canes that exhibit weakness or disease or are growing in strange directions.
(2) In late winter, remove any canes damaged by winter and thin the remaining canes as needed, leaving only healthy, well-spaced canes[].
This plant has perennial stems without prickles[] and is less invasive than the related Rubus odoratus[].
Plants in this genus are notably susceptible to honey fungus[].
Rubus parviflorus is distinguished from other flowering raspberries by its erect, unarmed stems, simple leaves, large flowers, white petals, glabrous, clavate styles, and yellowish to reddish stipitate glands covering most plant parts[].

Edible Uses

Fruit - raw or cooked[, , , ]. It makes excellent jams and preserves[]. The fruit can also be dried for later use[]. A sweet and pleasant flavour[, , ] though this is not always properly developed in the cooler summers of Britain[]. The fruit is very seedy[]. Rich in vitamin C[]. The red, hemispherical fruit is about 10 - 20mm in diameter[, ].

Young shoots - peeled and eaten cooked or raw[, , , , ]. The shoots are harvested as they emerge in the spring, and whilst they are still young and tender[, ]. They can be cooked like asparagus[]. The shoots are rich in vitamin C[].
Also great quantities of the tender young shoots were eaten raw in the spring[].

Flowers - raw[].

Medicinal

The leaves are antiemetic, astringent, blood tonic and stomachic[, ]. An infusion is used internally in the treatment of stomach complaints, diarrhoea and dysentery, anaemia, the spitting up of blood and to treat vomiting[, ]. An infusion has been taken by women when their periods are unusually long[].
A poultice of the dried powdered leaves has been used to treat wounds and burns[]. The leaves have been crushed and rubbed over the skin to treat pimples and blackheads[]. A poultice of the leaf ashes, mixed with oil, has been used to treat swellings[].

The young shoots are alterative and antiscorbutic[].

The roots are appetizer, astringent, stomachic and tonic[, ]. An infusion has been used by thin people to help them gain weight[]. An infusion has also been used in the treatment of stomach disorders, diarrhoea and dysentery[, ]. A decoction of the roots has been taken in the treatment of pimples and blackheads[].

Agroforestry Uses:

Plants are very vigorous and can be grown as a tall ground cover for large areas[].
The vigorous root system is effective in binding soil and so the plant is of value within its native range for erosion control[].

Other Uses

In North America used as a partner for crossings with Rubus idaeus, R. occidentalis and blackberries because of its adaptability to warmer climate and its resistance to anthragnose (cane spot)[].
R. parviflorus is valued for its genetic diversity for breeding. It has been identified as a genetic source of resistance for root rot in red raspberry (Rubus idaeus)[].

The leaves are used to line baskets etc for carrying soft fruit or other delicate items[, ].

A soap is obtained from the boiled bark[, , ].

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

Propagation

Seed - requires stratification, is best sown in early autumn in a cold frame. Sow stored seed as early as possible in the year in a cold frame and stratify for a month at 3°c if sowing later than late winter. 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.
Tip layering in July. Plant out in autumn.
Division in early spring.