Thimbleberry is a native semi-erect perennial, a rather thin, spindly shrub whose stems can reach up to 4 feet in height but tend to be sprawling.
Stems are without prickles but have yellowish to reddish glandular hair and are usually green in our area as old stems die back in winter.
The leaves, lower particularly, are wide (4 to 8 inches) and 5-lobed, resembling large glorified maple leaves, the lobes being shallow, pointed and unequally toothed. The leaf is long stalked with a cordate base. Stalks and lower leaf surfaces, particularly the main veins which are very prominent on the underside, usually have some glandular hair and the underside can sometimes be densely hairy. At the base of the leaf stalk are a pair of arrow-shaped stipules.
The inflorescence is a few flowers in a terminal loose stalked cluster.
Flowers are 5-part, up to 1-1/2 inches wide, with white overlapping petals resembling a single white rose, with a prolific number of stamens that have yellow anthers, surrounding the central receptacle composed on numerous yellow-green pistils. The styles are unique in Rubus in that they are thicker at the tip than at the base (said to be 'clavate'). The green calyx has lobes tipped with a long green slender appendage, both lobes and appendage are glandular hairy.
Fruit: Fertilized flowers mature into a pale orange-red fuzzy 1/2 inch thick, hemispheric shaped berry composed of 50 to 60 druplets, considered edible but not of great taste.
Habitat: Thimbleberry is a woodland plant requiring only partial sun and moderately moist soils, spreading by the underground rootstocks forming thickets.
Names: The genus Rubus is the Latin name for the brambles - raspberries, blackberries, etc. The species parviflorus, means 'with small flowers', being derived from the root parvi, meaning 'small'. The flowers are not small by Rubus standards, but the base word pau can mean "few" and if then "few flowers" we have made sense of it.
The author name for the plant classification from 1818 - ‘Nutt.’ is for Thomas Nuttall (1786-1859) English botanist who lived and worked in America from 1808 to 1841. On his many expeditions he collected many species that had been originally collected by Lewis and Clark but lost by them on their expedition return. He also collaborated with French botanist Francois Andre Michaux (1770-1855) in Michaux’s 3 volume North American Sylva.
Thimbleberry is sometimes called Salmonberry, including by Eloise Butler back in the 1900s, but that name is more correctly applied to Rubus spectabilis.
Comparisons: The most common species that looks like this one is the Purple Flowering Raspberry, Rubus odoratus, which has similar leaves, but larger purple flowers and outside of an ornamental planting that species will not be found in Minnesota. Thimbleberry can be a handsome shrub or high ground cover when grown in the right conditions.
These other examples of Rubus are or have been in the Garden: Dewberry, R. flagellaris; Blackberry, R. allegheniensis; Black Raspberry, R. occidentalis; and American Red Raspberry, R. idaeus var. strigosus.
Above: 1st photo - The rose-like flower with white petals and numerous stamens surrounding a group of yellow-green pistils. 2nd photo - The developing fruit of mid-July. Note on the calyx the thin linear appendage at the tip of the calyx lobes, also visible in the 1st photo.
Below: The Maple-like leaves. Stalks and stems and the underside veins of the leaf all usually have glandular hair.
Below: The mature fruit of late July. 2nd photo - Janice Stiefel, Wisconsin Flora
Below: Most all parts of the plant have glandular hair, including the flower calyx, the stem and leafstalk (1st photo) - note the thin appendages of the calyx lobes, (2nd photo) - note the small stipules at the base of the leaf stalk - and the underside veins of the leaf (3rd photo).
Notes: Eloise Butler introduced Thimbleberry to the Garden on April 26, 1913 with plants sourced from Kelsey's Nursery in North Carolina. In Sept. 1919 she sourced some from Lutsen, MN. More were planted in 1923, '25, ' 27, '28, and '32. Thimbleberry is not listed, however, on Martha Crone's 1951 census of plants in the Garden, but she later planted it in 1956. Gardener Cary George planted the species in 1994 and Curator Susan Wilkins in 2019. Thimbleberry grows in widely separated populations in the Great Lakes States and the Western United States. In Minnesota the only reported populations are along the roadsides near Lake Superior, which is similar to Wisconsin where most of the sightings are in counties along the Great Lakes.
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) See FNA (Ref. #W7) for a discussion of the current taxonomic thoughts regarding species and relationships." (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.
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"