Dwarf Red Blackberry is a native perennial low-growing bramble, with creeping above ground stems that root at the tips, but with erect flowering branches to 12 inches high. Stems are without prickles, without surface bloom, and can be smooth or with sparse to moderate hair.
Leaves are compound, 3 parted, rarely 5 parted. The terminal leaflet is diamond shape, tapering at the base to a short stalk. The lateral leaflets are more ovate, widest below the middle, with more truncate bases, without a stalk. They are also asymmetric in shape. All three leaflets have pointed tips and serrate to doubly serrate margins. The upper side is medium green and underside is slightly paler, with some sparse hair on the ribs. The leaf is stalked with a pair of oblanceolate (longer than broad, widest in upper third) stipules at the base.
The inflorescence has 1 to 3 flowers on stalks held above the leaves. The stalks have moderate to dense hair, which may be without glands or densely stipitate-glandular. The flower stalks rise from the crown or from nodes on the creeping stems.
Flowers are 5-part bisexual (perfect) flowers with white to pinkish petals, usually 4 to 8 mm long, 10 mm maximum, that are broadest above the middle, and 5 green triangular sepals that have velvety hair. Petals are slightly shorter than the sepals and fall away quickly. Sepals reflex when the flower is open. The center of the flower is a mass of carpels, each with a style, that will form the fruit. These are surrounded by a large number of stamens that have greenish-white filaments and yellow anthers. The flowers are small.
Fruit: Fertile flowers produce an edible berry composed of a number of drupelets that each contain a seed. When picked, the drupelets may separate from the core stem, but are usually attached and difficult to separate. Fruit is red at maturity, 0.5 to 1.4 cm in diameter.
Habitat: Dwarf Red Blackberry grows in moist soils, from swamps, bogs and moist woods to moist bluffs and sandy or gravely site, needing at least partial sun. The plant is longer-lived than the upland Red Raspberry, R. idaeus. It can be propagated from the seeds, which must be scarified and are best sown in early fall in a cold frame. Cuttings can propagated from the hardwood. Seeds are long-lived.
Names: The genus name Rubus is the Latin name for bramble and pubescens means 'downy' referring to the fine hair. The accepted author name for the plant classification - ‘Raf.’ refers to Constantine Samuel Rafinesque, (1783-1840), European polymath who traveled in the United States, lived here many years, collected specimens, and published over 6,700 binomial names for plants. He applied to be botanist on the Lewis & Clark expedition but Jefferson turned him down in favor of training Lewis to act as botanist and saving the expense of another person.
Comparisons: Being a plant of the wetlands limits which other red raspberries may be confusing with this species. The most notable would be the Arctic Raspberry, R. arcticus with which our species will hybridize. The Arctic plant has thicker leaves with blunt tips on the leaflets, more purplish flowers and smaller but deeper red to purplish berries. Ranges do overlap.
Another bramble that resembles this plant is Rubus flagellaris, and more properly takes the common name of Dewberry. This is a more upland species, but it also has creeping stems and those can root at the nodes and have prickles. These other examples of Rubus are or have been in the Garden: Wild Red Raspberry, R. idaeus; Thimbleberry, R. parviflorus; Black Raspberry, R. occidentalis; Blackberry, R. allegheniensis, and Purple Flowering Raspberry, R. odoratus.
Above: The small flowers have petals widest above the middle and triangular shaped sepals that have fine hairs. Numerous stamens with yellow anthers surround the central female carpels.
Below: The 3-parted leaf has a diamond shaped terminal leaflet on a short stalk, the lateral leaflets are asymmetrical. The underside (2nd Photo) is paler in color with some sparse hair on the ribs.
Below: 1st photo - This flower stalk and outside of the calyx show glandular hair. 2nd photo - a mature red berry.
Below: 1st photo - Drawing of Rubus pubescens 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. 2nd photo - a comparison of Arctic Blackberry, R. arcticus, which overlaps in range and hybridizes with R. pubescens. Photo ©Joshua A. Horkey, Wisconsin Flora.
Notes: Dwarf Red Raspberry is indigenous to the Garden; Eloise Butler cataloged it on May 21, 1907, using the older name of R. triflorus. It was on Martha Crone's 1951 list of Garden plants. Rubus pubescens is found in most counties of Minnesota with the exceptions being most of the drier SW counties. It is found throughout northern North America north of a line from Oregon to Illinois to New Jersey.
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 gives this disclaimer about the descriptions of the Rubus species: "Rubus is a very complex taxon with much hybridization, polyploidy, and apomixis occurring within and among taxa. The group is also difficult to separate into species since both first- and second-year growth are needed for identification. See FNA (Ref. #W7) for a discussion of the current taxonomic thoughts regarding species and relationships." (Ref. #28C)
Uses and medicinal lore: Besides producing edible fruit there is some literature on minor medicinal uses of the plant - undoubtedly limited by the distribution and quantity of fruit to be found. It is also reported that a dull blue dye could be obtained from the fruit.
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"