Rubus fruticosus complex

Name and classification

Rubus fruticosus L. agg. (complex)
Family Rosaceae

Common names

blackberry, dewberry

Disseminule

fruit segment (drupelet)

Description

Aggregate fruit a head of many drupelets, each containing one seed. Drupelets narrowly to broadly D-shaped or rounded triangular, ca. 2–3.2 mm long, 1.5–2.8 mm wide, 1–1.8 mm thick. Surface reticulate and/or wrinkled, with varying amounts of adherent pericarp. Color ranging from whitish, straw-yellow, amber, orange-red, reddish black, to nearly black. Embryo spatulate.

Identification considerations

It is frequently difficult to impossible to distinguish Rubus species by their fruits. Drupelets of Rubus species look very similar, and there is much variability within species. It is beyond the scope of this page to determine if there exist drupelet characters diagnostic for the many species within the R. fruticosus complex.

Similar species

Rubus moluccanus L.

Rubus—selected non-FNW species (not in R. fruticosus agg.)

Distribution

native to Europe

Species within the complex have become established in many temperate regions of the world, such as Australia, New Zealand, Afghanistan, India, Indonesia, Sri Lanka, Turkey, Chile, United States.

Habitat

humid and subhumid temperate; streambanks, irrigation ditch banks, disturbed areas, roadsides, farmlands, orchards

General information

The name Rubus fruticosus refers not to a single species, but is used in the aggregate sense, comprising some 2,000 described European species, these nearly all the European species in section Rubus, subgenus Rubus of the genus Rubus. The name is based on a mixture of R. plicatus Weihe & Nees and R. ulmifolius Schott. Many of the species arose as a result of hybridization and apomixis. All species belonging to R. fruticosus L. agg. are exclusively European, except for those that may have spread to other parts of the world.

Rubus fruticosus agg. species are perennial, erect and spreading shrubs with prickly stems and leaves, 1–2 m tall. These plants can spread rapidly, to form dense thickets impenetrable to people and animals. Sheep may get caught in the brambles and die. The thickets may dominate large areas, preventing the growth of other vegetation, and the dry underbrush creates a fire hazard. Goats reportedly consume the edible fruit and may help control infestations. The plants are spread by birds and other animals that eat the fruits.

A few selected Rubus species are discussed below.

Within R. fruticosus agg.:

Rubus armeniacus Focke (=R. discolor Weihe & Nees; R. procerus P.J. Muell.) (Himalayan blackberry) is a common non-native invading riparian areas in California and the Pacific Northwest, originally spread from Eurasia to Australia, New Zealand and S. Africa. Rubus laciniatus Willd. (cutleaf blackberry) is a closely related species. In addition to these two, the following six species are problem weeds in Australia: R. cissburiensis Barton & Riddelsd., R. selmeri Lindeb., R. polyanthemus Lindeb., R. ulmifolius Schott, R. vestitus Weihe & Nees, and R. rosaceus Weihe & Nees. R. vulgaris Weihe & Nees is reportedly one of the worst weeds in cultivation.

Not in R. fruticosus agg.:

Rubus allegheniensis Porter and R. hispidus L. are examples of native North American species in section Rubus, subgenus Rubus, but not in the R. fruticosus aggregate. Rubus spectabilis Pursh (salmonberry) is a native North American species in subgenus Idaeobatus, cultivated for ornament and found in the western U.S. Rubus ursinus Cham. & Schlecht. (California blackberry) is native to North America and is not noxious. Rubus rosifolius Sm. is an introduced raspberry (subgenus Idaeobatus) from Asia. In the U.S., it occurs only in Hawaii.

Rubus armeniacus Focke drupelets; dorsal view (right)

Rubus armeniacus Focke drupelets; dorsal view (right)

Rubus chloocladus  W.C.R. Watson drupelets; dorsal view (right)

Rubus chloocladus W.C.R. Watson drupelets; dorsal view (right)

Rubus plicatus Weihe & Nees drupelets; dorsal view (right)

Rubus plicatus Weihe & Nees drupelets; dorsal view (right)

Rubus rosaceus Weihe & Nees drupelets; dorsal view (right)

Rubus rosaceus Weihe & Nees drupelets; dorsal view (right)

Rubus ulmifolius  Schott drupelets; dorsal view (right)

Rubus ulmifolius Schott drupelets; dorsal view (right)

Rubus ulmifolius aggregate fruit

Rubus ulmifolius aggregate fruit

Rubus vulgaris  Weihe & Nees drupelets; dorsal view (right)

Rubus vulgaris Weihe & Nees drupelets; dorsal view (right)

Rubus vulgaris aggregate fruit

Rubus vulgaris aggregate fruit