Rubus multifer (Kinnickinnick Dewberry)
|Also known as:
|part shade, sun; average to dry sandy or rocky soil; prairies, savannas, woodland edges, rock outcrops
|May - June
|6 to 15 inches
|Wetland Indicator Status:
|MN county distribution (click map to enlarge):
|National distribution (click map to enlarge):
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Loose clusters on short lateral shoots along 1-year-old stems, each cluster with 1 to 6 flowers, usually on long, erect to ascending stalks (known as ascendate). Flowers are white, about 1¼ inch (2.5 to 3.5 cm) across with 5 rounded petals. In the center is a green cluster of many styles surrounded by a ring of numerous, creamy white-tipped stamens.
Cupping the flower are 5 green sepals, oblong-elliptic, pointed or with a short tail-like extension at the tip, the outer surface sparsely to moderately covered in non-glandular hairs. Flower stalks are similarly hairy and may have a few slender prickles.
Leaves and stems:
Leaves are alternate and palmately compound, non-flowering first-year stems (primocanes) with mostly 5 leaflets, sometimes 3 on the lower stem, and flowering second-year stems (floricanes) with mostly 3 leaflets. Leaflets are coarsely toothed around the edges, sparsely hairy on the upper surface, sparsely to moderately hairy on the lower, not typically velvety. The terminal leaflet on primocanes is 2½ to 3½ inches (6 to 9 cm) long, up to 2¾ inches (5 to 7 cm) wide, broadly egg-shaped to nearly round, widest below the middle, rounded to somewhat heart-shaped at the base, tapering to a pointed tip, sometimes abruptly so.
Leaflet stalks are sparsely to moderately covered in non-glandular hairs along with scattered curved prickles. At the base of the compound leaf stalk is a pair of appendages (stipules), lance-shaped to linear, up to ¾ inch (10 to 19 mm) long.
Prickles are up to 1/8 inch (2 to 3 mm) long, slender and needle-like to slightly broad-based, curved or declined, and often sparse. Stems are green to reddish, hairless, up to 8 feet (to 2.5 m) long but low-growing, low-arching or trailing along the ground and frequently rooting at the tips; stems die the second year after fruit matures. Colonies may also form from root suckers.
Kinnickinnick Dewberry reaches the northwestern edge of its range in east-central Minnesota. According to the DNR, it's primarily found in high-quality savanna remnants on the Anoka Sandplain, with scattered populations in rock outcrops of prairie habitats in the Saint Cloud area. Due to the limited and dwindling amount of suitable savanna habitat it was listed as a Special Concern species in 2013. Of note is it's been found more recently in dozens of sites around the Twin Cities Metro in utility corridors, railroad rights-of-way, roadsides, and various city and county natural or unmanaged areas, usually in open, sunny locations or in part shade.
Rubus is a large and difficult genus; both first year (non-flowering primocane) and second year (flowering/fruiting floricane) stems from the same plant may be necessary for a positive ID. Multiple species frequently grow together so stems from the same plant is recommended. Primocanes should be used for stem and leaf characteristics, floricanes mostly for just flowers and fruit. Characteristics to look for are the size and shape of the flower cluster as well as the flower, whether there are glandular and/or non-glandular hairs (on sepals, leaves, stalks and/or stems), whether there are any broad-based prickles or needle-like bristles, number of leaflets on the primocane and whether they are palmately or pinnately compound, whether canes are low-growing or trailing along the ground and/or root at the tip. In some species, the leaflet shape may also be relevant. Floricane leaves are frequently different from primocane leaves in shape and/or number of leaflets so are not a good substitute, and keep in mind that primocanes mature and tip-rooting occurs later in the season than peak flowering time.
In many references Rubus multifer is lumped in with Rubus flagellaris, along with other MN species R. ferrofluvius, R. ithacanus, R. plicatifolius, R. satis, and R. steelei, but we follow the treatments by Mark Widrlechner and documented by Welby Smith in his book “Trees and Shrubs of Minnesota”, which keeps them split as separate species. R. flagellaris is apparently a dumping ground for Dewberries that have broad-based prickles and stems that trail along the ground, rooting at the tips, but other characteristics can be rather variable.
Rubus multifer is identified by the combination of: lacking any glandular hairs; prickles usually sparse, slender and needle-like or more often slightly broad-based, curved or declined; primocane leaves with mostly 5 leaflets, sometimes 3 on the lower stem, lower leaf surface not typically velvety but variably hairy ranging from sparse to moderate; flowers mostly in a loose cluster on long ascending to erect stalks (ascendate), only 1 to 6 flowers per cluster; sepals and stalks sparsely to moderately covered in non-glandular hairs. Canes can reach 8 feet long (more often around 5 feet), are low-growing, frequently trail along the ground eventually rooting at the tips.
What catches my eye most often are the leaves: very coarsely toothed, the lateral leaflets very short-stalked so they tend to overlap, and the terminal leaflet very broad, nearly round, sometimes even with very shallow lobes near the base. When flowers or fruits are present the shape of the cluster can further distinguish it from other trailing species with 5 leaflets: it does not strongly resemble either a typical raceme or the flattish/convex cluster of a corymb.
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- primocane in mid June
- blooming in early June
- a loose colony in a prairie remnant
- larger, denser colony
- a trailing primocane in October
- canes frequently root at the tips
- stipules are lance-linear
- leaf underside is variably hairy, sparse to moderate
- flowers are few, usually on long, erect to ascending stalks
- flowers are ~1¼ inches (2.5 to 3.5 cm) diameter
Photos by K. Chayka taken in Hennepin, Ramsey and Washington counties.
Have you seen this plant in Minnesota, or have any other comments about it?