The blackberry is an edible fruit produced by any of several species in the Rubus genus of the Rosaceae family. The fruit is not a true berry; botanically it is termed an aggregate fruit, composed of small drupelets. The plants typically have biennial canes and perennial roots. Blackberries and raspberries are also called caneberries or brambles. It is a widespread, and well known group of over 375 species, many of which are closely related apomictic microspecies native throughout the temperate northern hemisphere and South America. Blackberries are perennial plants which typically bear biennial stems (“canes”) from the perennial root system.
In its first year, a new stem, the primocane, grows vigorously to its full length of 3–6 m (in some cases, up to 9 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 cane becomes a floricane and the stem does not grow longer, but the lateral buds break to produce flowering laterals (which have smaller leaves with three or five leaflets). First and second year shoots usually have numerous short curved very sharp prickles that are often erroneously called thorns. Prickle-free cultivars have been developed. Recently the University of Arkansas has developed primocane fruiting blackberries that grow and flower on first year growth much as the primocane-fruiting (also called fall bearing or everbearing) red raspberries do.
Unmanaged mature plants form a tangle of dense arching stems, the branches rooting from the node tip on many species 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.
Nutrients and antioxidant qualities
Blackberries are notable for their high nutritional contents of dietary fiber, vitamin C, vitamin K, folic acid – a B vitamin, and the essential mineral, manganese (table).
| Nutrient | Value per 100 grams | % Daily Value |
|---|---|---|
| Energy | 43 kcal | |
| 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, µg | 20 µg | 25% |
| Folic acid, µg | 36 µg | 9% |
| Carotene, beta | 128 µg | ne |
| Lutein + zeaxanthin | 118 µg | 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.
Nutrient content of seeds
Blackberries contain numerous large seeds that are not always preferred by consumers. The seeds contain some oil which is rich in omega-3 (alpha-linolenic acid) and -6 fats (linoleic acid), as well as some protein, dietary fiber, carotenoids, ellagitannins and ellagic acid.