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[
Rubus coptophyllus A.Gray
Rubus corchorifolius coptophyllus (A.Gray) Kuntze
Rubus corchorifolius palmatoides (Kuntze) Kuntze
Rubus corchorifolius palmatus (Thunb.) Kuntze
Rubus corchorifolius tanakae (Kuntze) Kuntze
Rubus dulcis Koidz.
Rubus edulis Koidz.
Rubus fauriei H.Lév. & Vaniot
Rubus grayanus yakumontanus (Masam.) Hatus.
Rubus horiyositakai Koidz.
Rubus incisus palmatoides (Kuntze) H.Lév.
Rubus omogoensis Koidz.
Rubus palmatoides Kuntze
Rubus similis Kuntze
Rubus sohayakiensis Koidz.
Rubus tanakae Kuntze
Rubus yakumontanus Masam.
Rubus palmatus is a deciduous shrub producing each year a cluster of prickly, biennial stems from a woody rootstock; the plant usually grows up to 180cm tall, but in warm, protected environments has been known to reach 600cm[
]. 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 is harvested from the wild for local use as a food. It is sometimes grown as an ornamental in gardens[
E. Asia - central and southern Japan
Hills and low mountains[
|Cultivation Status||Ornamental, Wild
Rubus palmatus can tolerate occasional, short-lived winter temperatures falling as low as -10°c, though it grows best in regions with milder winters and warm to hot summers[
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[
]. The yellow fruit is about 20mm in diameter[
The leaves are used as a tea substitute[
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[