Rubus parviflorus

The flowers are 2 to 6 centimeters (0.79 to 2.36 in) in diameter, with five white petals and numerous pale yellow stamens. The flower of this species is among the largest of any Rubus species, making its Latin species name parviflorus ("small-flowered") a misnomer.[8][13]

The fruit of the thimbleberry

The plant produces edible composite fruit approximately a centimeter (0.4 inches) in diameter, which ripen to a bright red in mid to late summer. Like raspberries, it is not a true berry, but instead an aggregate fruit of numerous drupelets around a central core. The drupelets may be carefully removed intact, separately from the core, when picked, leaving a hollow fruit which bears a resemblance to a thimble, perhaps giving the plant its name.[8][14]

Thimbleberry fruits are flatter and softer (more fragile) than raspberries, but similarly have many small seeds. Because the fruit is so soft, it does not pack or ship well, so thimbleberries are rarely cultivated commercially.

However, wild thimbleberries can be eaten raw or dried (the water content of ripe thimbleberries is quite variable), and can be made into a jam[15] which is sold as a local delicacy in some parts of their range, notably in the Keweenaw Peninsula of Upper Michigan. Thimbleberry jam is commonly made by combining equal volumes of berries and sugar and boiling the mixture for two minutes before packing it into jars. Without sugar, the cooked berries, with a distinguishing sweet-sour taste, keep for a few days in the refrigerator.

Cultivated plant in the Helsinki University Botanical Garden in Finland

Rubus parviflorus is cultivated by specialty plant nurseries as an ornamental plant, used in traditional, native plant, and wildlife gardens, in natural landscaping design, and in habitat restoration projects. The fruit has fragrance.[16] Thimbleberry plants can be propagated most successfully by planting dormant rhizome segments, as well as from seeds or stem cuttings.

The flowers support pollinators, including of special value to Native bees, honeybees, and bumblebees.[13] The fruit is attractive to various birds and mammals, including bears.[13][17] It is the larval host and a nectar source for the yellow-banded sphinx moth.[13]

Cultivars of the plant are selected for ornamental qualities, such as for their fragrant flowers and/or attractive fall foliage color.[18]

A double-flowered form of the thimbleberry was discovered near Squamish, British Columbia, by Iva Angerman (1903–2008) of West Vancouver.[19] This clone does not appear to be in commerce, but is grown in the Botanic Garden of the University of British Columbia, Vancouver, and in the Native Plant Garden of the Royal British Columbia Museum, Victoria.

Many parts of the plant were used in folk medicine by Native Americans.[15][18][20] A tea made from its leaves or roots was thought to be a treatment for wounds, burns, acne, or digestive problems.[21] As of 2019, there is no evidence from modern clinical research or practice that Rubus parviflorus is effective for treating any disease.

Thimbleberry leaves can be used as "toilet paper" when in the wilderness.[21]