In its first year, a new stem grows vigorously to its full length of 3-6 m, arching or trailing along the ground and bearing large palmately compound leaves with five or seven leaflets; it does not produce any flowers. In its second year, the stem does not grow longer, but the flower buds break to produce flowering laterals, which bear smaller leaves with three or five leaflets. First and second year shoots are usually spiny with numerous short curved very sharp thorns (thornless cultivars have been developed purposefully).
Unmanaged mature plants form a tangle of dense arching stems, the branches rooting from the node tip when they reach the ground. Vigorous and growing rapidly in woods, scrub, hillsides and hedgerows, blackberry shrubs tolerate poor soils, readily colonizing wasteland, ditches and vacant lots.
The flowers are produced in late spring and early summer on short racemes on the tips of the flowering laterals. Each flower is about 2-3 cm in diameter with five white or pale pink petals. The newly developed primocane produces flowers and fruits on the new growth.
The early flowers often form more drupelets than the later ones. This can be a symptom of exhausted reserves in the plant's roots, marginal pollinator populations, or infection with a virus such as Raspberry bushy dwarf virus. Even a small change in conditions, such as a rainy day or a day too hot for bees to work after early morning, can reduce the number of bee visits to the flower, thus reducing the quality of the fruit. The drupelets only develop around ovules that are fertilized by the male gamete from a pollen grain.
The soft fruit is popular for use in desserts, jams, seedless jellies and sometimes wine. Since the many species form hybrids easily, there are numerouscultivars with more than one species in their ancestry.
The blackberry is known to contain polyphenol antioxidants, naturally occurring chemicals that can upregulate certain beneficial metabolic processes in mammals. The astringent blackberry root is sometimes used in herbal medicine as a treatment for diarrhea and dysentery. The related but smaller European dewberry (R. caesius) can be distinguished by the white, waxy coating on the fruits, which also usually have fewer drupelets. (Rubus caesius) is in its own section (Caesii) within the subgenus Rubus.
In some parts of the world, such as in Australia, Chile, New Zealand and the Pacific Northwest region of North America, some blackberry species, particularly Rubus armeniacus (syn. R. procerus, 'Himalaya') and Rubus laciniatus ('Evergreen') are naturalised and considered an invasive species and a serious weed.
As there is forensic evidence from the Iron Age Haraldskær Woman that she consumed blackberries some 2500 years ago, it is reasonable to conclude that blackberries have been eaten by humans over thousands of years.
Numerous cultivars have been selected for commercial and amateur cultivation in the United Kingdom or United States.
'Marion' (marketed as "Marionberry") is an important cultivar cross between 'Chehalem' and 'Olallie' (commonly called "olallieberry") berries. It is claimed to "capture the best attributes of both berries and yields an aromatic bouquet and an intense blackberry flavor". The Marionberry was introduced by G.F. Waldo with USDA-ARS in Corvallis, Oregon in 1956. Adapted to western Oregon, the Marionberry is named after Marion County, Oregon, in which it was tested extensively. Olallie in turn is a cross between loganberry and youngberry. 'Marion', 'Chehalem' and 'Olallie' are just three of many trailing blackberry cultivars developed by the United States Department of Agriculture Agricultural Research Service (USDA-ARS) blackberry breeding program at Oregon State University in Corvallis, Oregon.
The most recent cultivars released from this program are the thornless cultivars 'Black Diamond', 'Black Pearl' and 'Nightfall' as well as the very early ripening 'Obsidian' and 'Metolius'. Some of the other cultivars from this program are 'Waldo', 'Siskiyou', 'Black Butte', 'Kotata Berry', 'Pacific' and 'Cascade'.
Trailing blackberries are vigorous, crown forming, require a trellis for support, and are less cold hardy than the erect or semi-erect blackberries. In addition to the Pacific Northwest of the USA, these types do well in similar climates such as the United Kingdom, New Zealand, Chile, and the Mediterranean countries.
Semi-erect, thornless blackberries were first developed at the John Innes Centre in Norwich, UK, and subsequently by the USDA-ARS in Beltsville, Maryland. These are crown forming, very vigorous, and need a trellis for support. Cultivars include 'Black Satin' 'Chester Thornless', 'Dirksen Thornless', 'Hull Thornless', 'Loch Ness', 'Loch Tay', 'Merton Thornless', 'Smoothstem' and 'Triple Crown'. Recently, the cultivar 'Cacanska Bestrna' (also called 'Cacak Thornless') has been developed in Serbia and has been planted on many thousands of hectares there.
The University of Arkansas has developed cultivars of erect blackberries. These types are less vigorous than the semi-erect types and produce new canes from root initials (therefore they spread underground like raspberries). There are thornless and thorny cultivars from this program, including 'Navaho', 'Ouachita', 'Cherokee', 'Apache', 'Arapaho' and 'Kiowa'. They are also responsible for developing the primocane fruiting blackberries.
In raspberries, these types are called primocane fruiting, fall fruiting, or everbearing. Prime-Jim and Prime-Jan were released in 2004 and are the first cultivars of primocane fruiting blackberry. They grow much like the other erect cultivars described above, however the canes that emerge in the spring, will flower in mid-summer and fruit in late summer or fall. The fall crop has its highest quality when it ripens in cool climates.
'Illini Hardy' a semi-erect thorny cultivar introduced by the University of Illinois is cane hardy in zone 5, where traditionally blackberry production has been problematic, since canes often failed to survive the winter.
The blackberry tends to be red during its unripe ("green") phase, leading to an old expression that "blackberries are red when they're green".
In various parts of the United States, wild blackberries are sometimes called "Black-caps", a term more commonly used for black raspberries, Rubus occidentalis.
Blackberry production in Mexico has expanded enormously in the past decade. While once based on the cultivar 'Brazos', an old erect blackberry cultivar developed in Texas in 1959, the Mexican industry is now dominated by the Brazilian 'Tupi' released in the 1990s. 'Tupi' has the erect blackberry 'Comanche' and 'Uruguai' as parents . In order to produce these blackberries in regions of Mexico where there is no winter chilling to stimulate flower bud development, chemical defoliation and application of growth regulators are used to bring the plants into bloom.
|Nutrients in raw blackberries|
|Nutrient||Value per 100 grams||% Daily Value|
|Fiber, total dietary||5.3 g||21%|
|Sugars, total||4.9 g|
|Calcium, Ca||29 mg||3%|
|Magnesium, Mg||20 mg||5%|
|Manganese, Mn||0.6 mg||32%|
|Copper, Cu||0.2 mg||8%|
|Potassium, K||162 mg||5%|
|Sodium, Na||1 mg||0%|
|Vitamin C, total ascorbic acid||21 mg||35%|
|Vitamin A, IU||214 IU||4%|
|Vitamin K, mcg||20 mcg||25%|
|Folic acid, mcg||36 mcg||9%|
|Carotene, beta||128 mcg||ne|
|Lutein + zeaxanthin||118 mcg||ne|
Blackberries rank highly among fruits for antioxidant strength, particularly due to their dense contents of polyphenolic compounds, such as ellagic acid, tannins, ellagitannins, quercetin, gallic acid, anthocyanins and cyanidins.
Blackberries have an ORAC value (oxygen radical absorbance capacity) of 5347 per 100 grams, including them among the top-ranked ORAC fruits. Another report using a different assay for assessing antioxidant strength placed blackberry at the top of more than 1000 antioxidant foods consumed in the United States.