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Thimbleberry

Rubus parviflorus

Common names 2

thimbleberry

western thimbleberry

Description 3

More info for the terms: eruption, rhizome, shrub, shrubs

This description covers characteristics that may be relevant to fire ecology and is not meant for identification. Keys for identification are available (e.g., [75,100,107,239]).

Thimbleberry grows as an erect, multibranched, leafy deciduous shrub that may reach 10 feet (3 m) tall [205,229,231]. Size and distinguishing characteristics relating to leaves, glands, and pubescence can be highly variable [25,107,171,176]. In Arizona, thimbleberry shrubs in the Pinaleno and Chiricahua mountains were low growing and "merely suffrutescent", but shrubs found on more favorable growing sites grew as shrubs up to 7 feet (2 m) tall [120]. In California, thimbleberry shrubs found near the coast are much hairier than those from more inland sites [100]. Thimbleberry stems and leaves are thornless [205,239]. Stems range from 2 to 15 mm in diameter [100,209] and are typically biennial. In west-central British Columbia, the majority of stems lived 2 years but some lived 3 years and produced large lateral branches [81]. Thimbleberry produces alternate, simple, maple-shaped leaves with 3- to 7-pointed lobes [107,181]. Leaves generally measure up to 8 inches (20 cm) long and wide and have irregularly serrate margins [181,205,209]. Leaf petioles are typically just slightly shorter than leaf blades [99,229]. Thimbleberry flowers and fruits develop on 2nd-year stems [81]. Flowers are often large (up to 2 inches (5 cm) across) [181,205] and occur in clusters of 2 to 10 at the branch ends [29,205,239]. Fruits are thick, firm, raspberry drupelets [146,205,231].

Thimbleberry often forms clumps or dense thickets [205] through an "extensive network" of rhizomes [181]. On 1-year-old clearcuts in Oregon's Coast Ranges, thimbleberry shrubs had rhizomes that averaged 79 inches (201 cm) long and 14.4 buds per 3 feet (1 m) of rhizome length. Roots of thimbleberry seedlings measured 16 to 20 inches (40-50 cm) long [148]. About 13 to 15 months after the eruption of Mount St Helens, thimbleberry shrubs excavated from sites with 2 to 8 inches (5-20 cm) of volcanic ash had a maximum root length of 3 inches (8 cm) and extensive rhizome development [9].

Germination 4

More info for the terms: cover, duff, litter

Thimbleberry seed viability is considered moderate, and maximum germination of 62% has been reported [81]. Seeds germinate best after cold stratification [106], and mineral soil is a better germination substrate than duff or litter [152]. Plant propagation studies conducted in British Columbia found that thimbleberry seeds soaked in water for 24 hours and chilled at 36 °F (2 °C) for 4 to 5 months germinated best [106]. In germination tests of thimbleberry seeds collected near the University of British Columbia campus, thimbleberry germination was significantly better for seeds in or on mineral soil than for seeds in or on duff and litter layers (P<0.05). Germination was relatively insensitive to light, occurring at shade levels ranging from 0% to 90% [152].

In Oregon, thimbleberry germination was greater in a growth chamber (22%) than in the field (up to 7.4%). Field sites were clearcut and burned stands in Oregon's Coast Ranges [148]. When germination and growth of thimbleberry were compared on pure alluvial sands, pure reservoir sediments, and a mixture of these sediments, germination and cover of thimbleberry were considerably greater on sand and mixed sediments than on reservoir sediments [158].

Importance to livestock and wildlife 5

More info for the terms: cover, forb, frequency, fresh, natural, shrub

Thimbleberry is an important food source for ungulates in the West and small mammals and birds throughout its range [82,88,185].

Elk and deer: Use of thimbleberry by elk, white-tailed deer, and mule deer can be substantial in western North America. Use may be heaviest in recently burned or logged areas, where thimbleberry is often abundant. Although thimbleberry was not generally considered preferred big game forage in northern Idaho, elk, white-tailed deer, and mule deer readily browsed thimbleberry on burned sites, especially 1-year-old burned sites in the western redcedar/Oregon boxwood habitat type [13]. On the west side of the Cascade Range in the Pacific Northwest, thimbleberry was considered a principal browse species for elk, white-tailed deer, and mule deer [160]. It was important summer elk browse in Douglas-fir forests in the southern Coast Ranges in Oregon. In logged areas, cover of thimbleberry was significantly (P<0.01) greater in exclosures protected from elk browsing than in unprotected areas [219]. In northern Idaho, thimbleberry is considered to have only intermediate palatability for elk, but in the summer, its leaves were consumed a "fair" amount by elk on the Selway Game Preserve. Because of thimbleberry's abundance in that area, it was considered an important component of elk diets [244]. Based on 2 years of fecal analyses in the White Mountains of Arizona, thimbleberry made up 19.5% of female, 11.5% of male, and 11.3% of elk calf diets in the spring and 8.1% of female and male and 2.2% of calf diets in the summer [234]. In coastal forests on southern Vancouver Island, thimbleberry leaves were rated as having low to moderate importance as a mule deer summer food [41]. In Oregon, thimbleberry was a preferred mule deer food and typically eaten most in summer and early fall [61,147,159]. About 10 years after a fire in the Tillamook burn area, mule deer use of thimbleberry was "extensive" [101]. In the upper Selway River drainage of east-central Idaho, mule deer did not feed on thimbleberry between January and May, but in July, thimbleberry frequency in mule deer diets was 100% [121]. When captive mule deer were offered fresh thimbleberry forage collected from parts of northern Utah, they avoided it from 31 May to 20 June but preferred it from 1 August to 22 August [204].

Moose: Thimbleberry was important summer browse for moose near Jackson Hole, Wyoming [105] but was browsed little by moose in Isle Royale National Park, Michigan [115,179]. Thimbleberry buds were eaten in some areas of the Park in early May when moose populations were near peak levels, but in the majority of areas, thimbleberry was not browsed at all [131,172].

Bears: Several sources indicate that bears feed on thimbleberry fruits and shoots [50,82,188]. In northeastern Minnesota, thimbleberry is listed as a major food source for American black bears [188].

Small mammals: In the reviewed literature (as of 2012), a variety of small mammals were found to feed on thimbleberry fruits, but the true variety and extent of thimbleberry use by small mammals is not likely captured in this short discussion. Squirrels, chipmunks, woodrats, voles, mice, and American martens [82] have all fed on thimbleberry. In Oregon, Townsend's chipmunks, Pacific jumping mice, and deer mice ate thimbleberry fruits in the summer and fall, and dusky-footed woodrats fed on thimbleberry leaves [147]. Along the Oregon Coast from Coos to Tillamook counties, white-footed voles trapped in the red alder/salmonberry habitat type had little thimbleberry in their diets from February to March and none from June to August, but they had 14% in November diets [233]. In Glacier National Park, American marten scat was collected for 6 years, and Rubus spp. seeds were found in scat collected in the summer of all years. The greatest amount of Rubus spp. seed in scat was 12.6% [238]. In northern Minnesota, thimbleberry was recovered from 11% of the stomachs and 12% of the cheek pouches of least chipmunks captured in September. As many as 190 Rubus spp. seeds were recovered from one stomach and about 400 from a single cheek pouch [4].

Birds: A variety of birds feed on thimbleberry fruits; however, this discussion likely represents only a small sample of the true variety and extent of the use of thimbleberry by North American birds. A review reports that thimbleberry fruits can make up 10% to 25% of upland game bird diets [145]. On Vancouver Island, thimbleberry fruits were taken by American robins, northwestern crows, and Swainson's thrushes [27]. In northern California, thimbleberry fruits were a major food source for band-tailed pigeons from mid-May to mid-June [76,104]. In redwood forests, researchers observed at least one instance of varied thrushes feeding on thimbleberry [21].

Palatability and nutritional value: As browse, thimbleberry appears most palatable from late spring to early fall, given its high rates of use at this time [61,147,219,234]. In Washington, palatability of thimbleberry browse is considered fair for domestic sheep, birds, and small mammals but poor for cattle and horses. Energy and protein values for thimbleberry fruits and browse are considered low [129]. Analyses indicate that thimbleberry nutritional content is sufficient for moose, but in Isle Royale National Park, moose almost never feed on thimbleberry, possibly because of thimbleberry's tannin and cardiac glycoside contents [22]. In controlled feeding trials, yellow-pine chipmunks consumed more thimbleberry than cedar waxwings. The preference ranking of thimbleberry among 19 to 20 other fleshy-fruited plant species was much lower for yellow-pine chipmunks than for cedar waxwings [23].

Nutritional information related to thimbleberry was limited to the western United States. In western Oregon, thimbleberry was most nutritious in midsummer and was generally a poor winter food; however, winter protein content was much greater on very recently burned sites. On a 6-year-old burned site, the protein content of thimbleberry averaged 4.7%, and on a 3-month-old burned site, protein content averaged 11.6% [61]. When seasonal protein contents were compared on a site burned less than 6 years earlier, summer protein content was twice that of winter. Of the 6 browse species evaluated, thimbleberry had the lowest protein content [62]. In north-central Idaho, researchers found that prior livestock grazing can affect protein content of thimbleberry browse. Within a recent clearcut, fall crude protein and available protein values were higher on plots grazed in early and late summer by domestic sheep than on ungrazed plots [7]. The nutritional content of thimbleberry fruits collected in late summer from grand-fir forests in Washington's Rainbow Creek Research Natural Area, based on dry pulp measurements was: protein 4%, lipid 2.3%, neutral detergent fiber 18.6%, calcium 0.5%, and potassium 1.1%. Compared to other shrub and forb species in the study area protein, lipid, and potassium content for thimbleberry was low, but fiber and calcium content was high [180].

Cover value: Although cover value of thimbleberry was not described in detail in the reviewed literature (as of 2012), its multibranched structure and large, broad leaves (see Botanical description) suggest it probably provides important cover for small mammals and birds.

Other uses and values 6

More info for the terms: fresh, shrubs, vines

Humans consume thimbleberry fruits; the fruits are considered more flavorful in the eastern than western range or in areas receiving high amounts of rainfall [231]. Fruits are described as tasty in Michigan [232]. The Nez Perce Indians preferred fruits from shrubs growing in mountainous areas [144]. Many indigenous people inhabiting regions along the Pacific Coast, including the Haidi [173], Kwakiutl [224], Hoh, and Quileute Indians [183], ate thimbleberry fruits fresh and preserved them for later use. Thimbleberry sprouts and fruits are high in vitamin C [173]. Other uses included: boiling thimbleberry leaves with trailing blackberry (Rubus ursinus) roots and vines into a tea to treat vomiting and spitting up blood, sprinkling dried thimbleberry leaf powder into wounds to aid healing [224] and into burns to lessen scarring [88], using thimbleberry leaves to catch menstrual blood and shorten the duration of a period [224], boiling thimbleberry leaves into a tea to treat anemia, boiling thimbleberry bark to be used in soap [88], and chewing on dried brown thimbleberry leaves to ease stomach aches or diarrhea [223]. Thimbleberry stems were used by the indigenous people of the Salmon River-Cascade Head area of the Oregon Coast in basket making [249].

Edible 7

In addition to be flavorful, the plant has many herbal uses. The berries are tasty and can be stored for later consumption as Native Americans did. The leaves can be boiled into tea that can have herbal uses such as stopping vomit.

Sources and Credits

  1. (c) Jerry Kirkhart, some rights reserved (CC BY), http://www.flickr.com/photos/jkirkhart35/3666734197/
  2. Public Domain, http://eol.org/data_objects/24094389
  3. Public Domain, http://eol.org/data_objects/24638752
  4. Public Domain, http://eol.org/data_objects/24638760
  5. Public Domain, http://eol.org/data_objects/24638771
  6. Public Domain, http://eol.org/data_objects/24638773
  7. (c) jihyunan, some rights reserved (CC BY-SA)

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