Black Raspberry is a native perennial shrubby plant that produces arching canes, up to 6 feet long, that usually live for two years. The first year, they may root at the tip if they touch ground. There is little branching. The canes are green initially, then develop a purplish-red color, usually with a white bloom, and hooked prickles. The prickles are sparse, long, thin but with wide bases. Second year canes have a darker bark without the bloom.
Leaves are alternate. The leaf can appear undivided on the upper stem sections but usually 3 to 5 parted with irregular teeth and small prickles on the leaf stalk. Flowering canes have 3-parted leaves. First year canes can have 5-parted leaves. The terminal leaflet has a short stalk, the lateral leaflets are usually not stalked (sessile). The upper side is light to medium green and underside is much paler, almost white due to soft fuzzy hair.
Inflorescence: The flowers and later the fruit are in a dense umbel like cluster of 3 to 7 flowers, that occurs on new short side branches that grow from the second year cane or occasionally, springs from the leaf axils. First year canes are vegetative only.
Flowers: This raspberry has small 1/2 inch 5 part flowers with the white petals much shorter than the green sepals. Petals are oblong with narrowed bases and pointed tips. Sepals are triangular and hairy and widely spreading. In the center of the flower are the carpels that produce the drupelets, each with its own style. Surrounding them are many stamens with club-shaped yellow anthers.
Fruit: Fertile female flowers produce an edible juicy berry composed of multiple drupelets, each drupelet containing a single seed. The berry is about 1/3 to 1/2 inches across with a hollow (depressed) base when separated from the stem, which it easily does. The fruit turns purple-black when mature, however, sometimes the fruit is yellow as a result of a gene mutation that controls the anthocyanin production in the fruit. The fruit (black or yellow) tastes the same but tastes different from the Blackberry, Rubus allegheniensis.
Habitat: Black Raspberry grows in rich soils, needing at least partial sun. It will fruit only with adequate sun and consistent moisture. The root system is a branching taproot.
Names: The genus name Rubus is the Latin name for bramble and occidentalis refers to "western". The accepted author name for the plant classification, 'L.', refers to Carl Linnaeus (1707-1778), Swedish botanist and the developer of the binomial nomenclature of modern taxonomy.
Comparisons: Rubus is complex for identification. These other examples of Rubus are or have been in the Garden: Wild Red Raspberry, R. idaeus; Thimbleberry, R. parviflorus; Dewberry, R. flagellaris; Blackberry, R. allegheniensis. and Purple Flowering Raspberry, R. odoratus.
Above: Drawing from Britton, N.L., and A. Brown. 1913. An illustrated flora of the northern United States, Canada and the British Possessions. 3 vols. Charles Scribner's Sons, New York.
Below: The flowers have green sepals much longer than the white petals. The female parts of the flower form the center hemisphere and are surrounded by the male stamens, which have long filaments and yellow anthers, which turn dark at pollen maturity. The nectar for the bee is at the base of the stamens.
Below left: A 5-parted leaf typical of a leaf on a new first year cane. The underside of leaves is soft from many fine hair.
Below: Second year fruiting canes have 3-parted leaves.
Fruit: Green fruit form in mid to late June, turning first to red and then to black by Mid-July.
Below: Canes have hooked prickles with wide bases. 2nd photo - Mid-summer fruit turning black. When mature, fruit separates easily from the stem core.
Below: Canes typically arch over. Second year fruiting canes take on a dark reddish coloration, although the fruit appears on new growth lateral shoots from the old cane.
Notes: Eloise Butler had catalogued Black Raspberry in her plant index as present in the Garden area when she noted on July 11, 1914 "Found also Rubus occidentalis on Plateau!" The plant is native to Minnesota, primarily in counties in the SE quadrant of the state (including the metro area) and a few scattered counties elsewhere.
Species: The Minnesota DNR lists 38 species of Rubus in their county location records. The U of M Herbarium makes a list of 54 species that are present or have been reported at one time to be present and has given this disclaimer about the descriptions of the Rubus species: "Rubus is a a very complex taxon with much hybridization, polyploidization, and apomixis occurring within taxa. The group as a whole is difficult to separate into species (especially since both first and second year growth are needed for identification) and there has been much disagreement regarding species distinctions, particularly when statewide or regional populations are considered in the absence of the wider distributions of the species." (Ref. #28C)
Uses: Besides producing an edible fruit, Densmore (Ref. #5) reports that the Minnesota Chippewa used the root of the plant to make a decoction for women to take 'often and freely' daily to reduce pains of the back and female weakness. The decoction usually included root portions of another species, boiled in a quart of water.
References: Plant characteristics are generally from sources 1A, 32, W2, W3, W7 & W8 plus others as specifically applied. Distribution principally from W1, W2 and 28C. Planting history generally from 1, 4 & 4a. Other sources by specific reference. See Reference List for details.
Identification booklet for most of the flowering forbs and small flowering shrubs of the Eloise Butler Wildflower Garden. Details Here.
Friends of the Wild Flower Garden, Inc. Text and photos are by G. D. Bebeau unless otherwise credited. "www.friendsofthewildflowergarden.org"