Dewberries are very low growing native perennial shrubs of the Rubus genus; Northern Dewberry has canes usually less than 8 feet long, many times shorter, (but can grow much longer in the right environment). They are usually prostrate and live for two years. First year canes can root at the tips. The canes are green initially, turning reddish with age and have very small but stout thorns that have a wide base and a bit of a hook.
The leaves are alternate and divided into 3 doubly toothed leaflets, sometimes 5. The terminal leaflet has a short stalk (petiole). Each full leaf has a long prickly stalk to the stem, where there is a pair of small narrow stipules. The upper surface is a deep green, the underside a pale green with fine hair and longer hair on the margin and veins.
The inflorescence is a small cluster of up to five stalked flowers rising from a new short branch on the second year cane.
Flowers: The flower resembles the Blackberry (R. allegheniensis); flowers are 3/4 to 1 inch wide, with five wrinkly white petals that have rounded tips and narrow bases, and five narrowly ovate shaped green sepals that are much shorter than the petals. The central part of the flower has numerous carpels, each with a style, and these are surrounded by numerous stamens on long thin filaments ending in yellow-green anthers.
Fruit: Fertile flowers develop into an edible 1/2 to 3/4 inch long berry composed on numerous drupelets, each of which contain a seed. The fruit matures from green to red to black at maturity.
Habitat: Dewberry tolerates a wide range of soils and mesic to dry conditions. For fruiting full sun is best, partial sun tolerated. Besides stem rooting, the plant will reseed itself. It grows from a taproot with fibrous roots.
Names: The genus name Rubus is the Latin name for bramble and the species name flagellaris refers means 'whip-like' and refers to the long supple new shoots. The author name for the plant classification, ‘Willd.‘, refers to Carl Ludwig Willdenow (1765-1812), German botanist, a founder of the study of the geographic distribution of plants. He was director and curator of the Botanic Garden of Berlin.
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; Black Raspberry, R. occidentalis; Blackberry, R. allegheniensis, and Purple Flowering Raspberry, R. odoratus.
Above: Dewberry is a low-growing shrub with prostrate stems. Drawing courtesy USDA-NRCS PLANTS Database / USDA NRCS. Wetland flora: Field office illustrated guide to plant species. USDA Natural Resources Conservation Service.
Below: The flower has 5 wrinkly white petals, resembling the Blackberry.
Below: 1st photo - The short flower sepals with their pointed tips. Note the fine hair on the stalks. 2nd photo - A prostrate stem showing the slightly hooked prickles and the stipules at the base of the emerging leaf.
Below: 1st photo - Green berries of late June. 2nd photo - Fruit turning red in mid-July. Final maturity color is black.
Below: 1st photo - The terminal leaflet has a short stalk (petiole), the side leaflets are sessile. 2nd photo - The underside of the leaf is much paler in color with fine hair. Longer hair on the margin and veins.
Notes: Dewberry was not listed on Martha Crone's 1951 inventory of plants in the Garden at that time, but was present by the time of the 1986 census. It is widespread in the eastern half of the United States and Canada. In Minnesota it is native but reported on the Vascular Plants Of Minnesota Annotated Checklist (Ref. #28C) as being a " recognized taxon for Minnesota; but species limits defined differently among authors. The common view of this taxon (Alice et al. in press) is of an extremely polymorphic taxon when considered across its range in the US and Canada, with some characters subject to environmental variation and inter-gradation common among the variants." The older checklists shown it as present in only eleven widely scattered counties however, the current DNR census does not list it as present in any county.
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 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)
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.
Friends of the Wild Flower Garden, Inc. Text and photos are by G. D. Bebeau unless otherwise credited. "www.friendsofthewildflowergarden.org"