American Blackberry
Rubus cuneifolius
NEMBA: Category 1b
English: American Blackberry, Sand Blackberry, Florida Blackberry, Dewberry, American Bramble, Bramble
Afrikaans: Amerikaanse Braam, Stekelbraam
Misapplied scientific names: Rubus fruticosus
Rubus cuneifolius, commonly known as American Blackberry, is a scrambling, thorny, semi-evergreen to deciduous shrub that forms dense, tangled thickets. Its woody stems, called canes, are armed with numerous sharp, flattened prickles and often arch or trail along the ground, rooting where their tips touch the soil. Its leaves are typically divided into three (trifoliate) leaflets, with the central leaflet often having a distinctive wedge-shaped (cuneate) base. In spring and early summer, it produces clusters of white, five-petalled flowers, which then develop into shiny black, edible berries that resemble small thimble-like fruits.
This plant is a severe invasive species in South Africa, especially in disturbed areas, forest margins, and grasslands, as it spreads rapidly through its rooting canes and seeds, forming impenetrable thorny barriers that displace indigenous plants and make land unusable.
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Origin:
Native to the southeastern United States.
Distinguishing features:
Extremely thorny canes: Stems (canes) are very prickly, covered with numerous, strong, sharp, flattened, and often reddish-brown prickles.
Trifoliate leaves with wedge-shaped central leaflet: Leaves are usually divided into three leaflets, with the central one often distinctly wedge-shaped at its base. Leaflets can be hairy on the underside.
White, five-petalled flowers: Small, white flowers with five petals, produced in clusters.
Shiny black, edible berries: Clusters of juicy, black, aggregated fruits (like miniature bunches of grapes) that are typically sweet and delicious when ripe.
Arching and rooting canes: Canes grow in an arching manner, with their tips often touching the ground and rooting, allowing the plant to spread vegetatively over large areas.
Overall appearance:
A formidable, scrambling, thorny shrub that forms dense, tangled thickets. It is characterised by its prickly stems, three-part leaves, white flowers, and black berries.
Height:
Canes typically grow 1 to 2 metres tall but can sprawl extensively.
Width:
Forms dense, spreading clumps or thickets that can cover many square metres due to its vigorous growth and rooting canes.
Leaves:
Semi-evergreen to deciduous, alternate, and typically trifoliate (divided into three leaflets), though sometimes 5-foliate on vigorous shoots. The leaflets are oval to elliptical, 3 to 8 centimetres long, with sharply toothed margins. The central leaflet often has a distinctive wedge-shaped (cuneate) base. They are dark green above and paler, sometimes hairy, on the underside.
Flowers:
Small, white, five-petalled, about 1.5 to 2.5 centimetres in diameter, with numerous stamens. They are borne in clusters (racemes) at the ends of branches or in leaf axils. The flowers are hermaphroditic.
Flowering season (South Africa):
Mainly flowers in spring to early summer (around September to December), but can flower sporadically later in the season.
Fruits:
Aggregated fruits (berries), typically round to conical, 1 to 2.5 centimetres long, composed of many small, juicy drupelets. They are initially green, turning red, and finally shiny black when ripe. They are sweet and edible.
Seeds:
Small, hard, roughly oval seeds, each contained within a drupelet of the fruit. Numerous seeds are produced per berry.
Bark:
Canes are typically reddish-brown to greenish-brown, often covered in a whitish waxy bloom. They become woody and tougher with age.
Thorns:
Canes are densely covered with numerous, stout, rigid, flattened, and often recurved (hooked) prickles (spines), typically 5-10 millimetres long. These make the plant very difficult to penetrate.
Wood:
The canes are woody but typically not of timber quality.
Roots:
Develops a robust, fibrous root system that produces new canes (suckers), enabling rapid vegetative spread. Its canes also root readily when they touch the ground, forming new plants.
Soil type:
Highly adaptable to a wide range of soil conditions, including poor, degraded, sandy, or clay soils. It tolerates varying pH levels and prefers moist but well-drained sites, but can also withstand some drought.
Aspect:
Prefers full sun for optimal growth and fruit production, but can tolerate partial shade. It thrives in disturbed areas, forest margins, and open ground. It is tolerant of moderate frost.
Edibility:
The ripe black berries are edible and have a sweet flavour. They can be eaten fresh or used in pies, jams, and desserts.
Toxicity:
Generally considered non-toxic, with the berries being a popular food source. The main physical hazard is its very sharp prickles.
Uses:
Primarily cultivated for its edible berries. In South Africa, it was likely introduced for this purpose and as an ornamental or hedging plant.
Ecology:
As an alien invasive plant in South Africa, Rubus cuneifolius is a very severe threat, particularly in higher rainfall areas, grasslands, fynbos, forests, and disturbed sites. It forms dense, impenetrable thickets that completely outcompete and displace indigenous vegetation, reducing biodiversity and altering natural habitats. Its aggressive vegetative spread (through rooting cane tips and suckers) and prolific seed production (dispersed by birds and mammals attracted to its edible berries) allow it to rapidly colonise large areas. These thorny thickets make land inaccessible for grazing livestock and wildlife, reduce agricultural productivity, and can increase fire risk by providing dense fuel loads.
Distribution and habitat:
Widely cultivated and extensively naturalised and highly invasive throughout the higher rainfall and temperate regions of South Africa. It is a major problem in the Eastern Cape (very common around Kenton-on-Sea, particularly in disturbed areas, forest margins, grasslands, and along roadsides), KwaZulu-Natal, Mpumalanga, Limpopo, Western Cape, and parts of Gauteng and Free State. It invades grasslands, fynbos, open woodlands, forest margins, riparian zones, roadsides, and abandoned farmlands.
Derivation of name:
The genus name Rubus is the classical Latin name for brambles or blackberries, referring to their rough, prickly stems.
The species epithet cuneifolius is Latin for "wedge-leaved," referring to the often distinctive wedge-shaped base of the central leaflet.
"American Blackberry" refers to its native origin.
Historical aspects:
Rubus cuneifolius was introduced to South Africa as a fruit-bearing plant, likely in the late 19th or early 20th century, for its edible berries. Its vigorous growth, adaptability, and the appeal of its fruits (which led to wide dispersal by birds and animals) quickly facilitated its escape from cultivation. It has since become one of the most aggressive and widespread invasive plants in South Africa, causing significant ecological and agricultural damage, particularly in grazing lands and natural ecosystems.
Interesting facts:
This plant is basically a superhero of spreading! Its long, arching stems can touch the ground and sprout new roots, creating new plants and helping it take over huge areas!
It's covered in super sharp prickles, like a thorny bodyguard, which makes it nearly impossible for anything (or anyone!) to walk through its thickets.
Even though it's a thorny menace, it produces delicious, juicy black berries that are great for eating fresh or making jams!
Birds and animals absolutely love munching on these berries, which is why this plant spreads so fast – they're basically its little seed-delivery service!
Friendly alternatives:
Forest Num-num
Carissa bispinosa subsp. bispinosa
Cape Honeysuckle
Tecoma capensis
Plant type:
Semi-deciduous, deciduous, shrub or scrambler
Plant family:
Rosaceae (Latin plant name) - Order: Rosales