Dewberries are very low growing native perennial shrubs of the Rubus genus. As explained elsewhere on this page, there is considerable variation in the characteristics of the plants now grouped as Northern Dewberry: The species 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 prickles that have a wide base and a bit of a hook, but the number, density and shape of the prickles is highly variable.
The leaves are alternate and divided into 3 doubly toothed leaflets, sometimes 5. The amount of serration on the leaf margin is highly variable. 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 (usually) one to three 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. Flower stalks are usually with hair and sometimes with prickles.
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. Fruit separates from the stem with the torus (the tip of the flower stalk) attached.
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, from 1809 - ‘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. Over many years a number of Rubus variations were described as separate species. USDA (Ref.#W2) lists 28 of those former separate species that have now been re-grouped under R. flagellaris. Flora of North America (Ref. W7) lists 108 including subspecies! See page bottom for more explanation.
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: Eloise Butler first planted Dewberry on Oct. 5, 1922 with plants sourced from the vicinity of Anoka MN. She used one of the older names for the plant - Rubus villosus. More were planted in 1923 and '28. 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 Checklist of the Vascular Flora Of Minnesota (Ref. #28C) as follows: "The common view of this species (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 much intergradation common among the variants. Some authors (e.g., Smith 2008) take a restricted view and separate the variants as species." The Minnesota DNR lists 26 species of Rubus in their county location records. They do not list R. flagellaris as a species (2019) but instead list 4 species that have been now placed under R. flagellaris. Most of the county locations are in the northern and northeastern part of Minnesota. The four species are. R. ferrofluvius, R. ithacanus, R. multifer, R. satis.
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"