Recognized as a distinct species in the USDA 'Plants Database' https://plants.usda.gov/core/profile?symbol=RUJA, this species is treated in the Flora of N. America as a putative hybrid involving Rubus hispidus L., and Rubus setosus Bigelow[
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: Spreading Dewberry
Rubus jacens is a deciduous shrub producing each year a cluster of slender, low-arching to more or less prostrate, prickly biennial stems growing 60 - 100cm long from a woody rootstock. The stems only produce leaves, and do not flower, in their first year, forming flowering branches in their second year and then dying after fruiting. Plants usually form new roots in the autumn at the tips of 1 year old stems, thus producing new plants and forming thickets of growth,
The plant is harvested from the wild for local use as a food.
Eastern N. America - Vermont, New Hampshire, New York and Pennsylvania.
Dry pastures and clearings[
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Species in this genus are generally easily grown in a good well-drained loamy soil in sun or semi-shade[
Plants in this genus are notably susceptible to honey fungus[
Fruit - raw or cooked[
]. Sweet and pulpy. The black, globose fruits comprise 1 - 10 drupelets each around 3 - 4mm in diameter.
A purple to dull blue dye is obtained from the fruit[
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[