The thimbleberry is a North American variety of Rubus, with the scientific name Rubus parviflorus. It can be easily distinguished from other related species because it lacks prickles.
The thimbleberry plant is a shrub with a very high density. It expands through an underground rhizome and grows in large groups, with a maximum height of about 2.5 meters. Its canes are long but thin, with a diameter under 1.5 cm. Unlike most other varieties of Rubus, it has pretty large palmate leaves, reaching a maximum size of 20 centimetres. They have a soft texture and consist of five lobes each.
Of all Rubus species, the thimbleberry has one of the largest flowers. This makes the second part of its Latin name, parviflorus, quite incorrect, since it means “with a small flower”. The flowers have a diameter between 2 and 6 centimetres and consist of five white petals each, with many stamens with a white or yellow color.
At the end of summer, the edible fruits of the thimbleberry become ripe. These have a vivid red color at maturity, with a size of about one centimetre. Even if the fruits are popularly known as berries, they are not real berries but rather composite fruits, consisting of many small drupes bound together by an inner core. If the core is carefully removed after harvesting, the remaining fruit has a hole in the middle. The similarity to a sewing thimble probably gives the plant its name.
When compared to raspberries, the fruits of the thimbleberry are smaller, with a flatter profile and a softer texture. They also have a larger number of seeds. It is rarely cultivated, since the soft consistency makes it unsuited for transport, so it has limited commercial value.
The wild fruit is still harvested for its particular taste. It can be eaten raw from the wild or preserved in dried form but is mostly found as a jam. In some areas, especially in the Keweenaw Peninsula in the northern part of Michigan, thimbleberry jam is considered a traditional local delicacy. The jam is very easy to prepare by mixing the fruits with an equal amount of sugar, then boiling it for just two minutes. The jam can be then transferred into jars. Boiling the fruits without sugar produces a paste with a sweet and sour taste that can be preserved in the refrigerator and used as an ingredient in vinaigrettes and dessert dishes.
The thimbleberry is also important for the local wildlife. Wild bees, honeybees and bumblebees feed on its nectar and pollinate flowers, while birds consume the ripe fruits. The yellow-banded sphinx butterfly relies on the thimbleberry as both a source of nectar and a host for its larvae.
Berries, leaves, roots.
The Native American tribesmen were aware of the medicinal properties of the plant and used most parts of it to cure various diseases. Due to the very high content of vitamins A and C, the fruits are a great counter for scurvy, a disease caused by a lack of vitamins. Leaves can be applied on the skin when fresh as a cure for acne, or dried and ground into a powder that can be used to prepare a poultice useful in the treatment of burns and wounds. Diarrhea, nausea and dysentery can be treated with a tea brewed from either the leaves or the roots. An unconventional use of the plant’s leaves is as an alternative for toilet paper.
The thimbleberry is known to boost appetite and has a toning effect on the stomach, relieving pain in the area. Several parts of the plant, such as the leaves, roots and fruits, can reduce swelling, clean wounds and prevent scars.
Due to the powerful package of vitamins in its composition, consuming the fruit prevents scurvy and boosts the reaction of the immune system. Acne can be healed faster by applying crushed leaves, while anemia and stomach disorders can be cured with thimbleberry tea. Roots are able to boost appetite and act as a general tonic.
In order to reduce the risk of scars, you can apply a powder prepared from dry leaves on wounds. Steaming the face with leaves or bark is known to reduce sebum secretions. These effects also make the leaves and bark a useful ingredient in some herbal cosmetic products. Thimbleberry has been known for a long time as an effective counter for tooth pain.
A tea can be brewed from both the leaves and the fresh shoots. The berries are edible in raw form but are usually prepared as jams or jellies. They can also be dried for longer preservation or added as a tasty ingredient in milkshakes, desserts, pies and bakery products. Young shoots are also edible, either as green vegetables or added as a raw ingredient in salads. Thimbleberries pair well in salads, with other fruits.
Habitat and cultivation
The species is quite adaptable, it likes to grow in moist open spaces but tolerates a wide range of other locations. Thimbleberry likes disturbed grounds, where it can be found in large numbers, and also enjoys the edges of forests and riparian areas. It can also be found in forests with deciduous or coniferous trees, as well as edges of forests. The plant requires well-drained soils, such as lower or upper floodplains, since it can’t survive if the roots are under water.
As long as the soil has good drainage, the thimbleberry is very resilient and can survive in a variety of locations. It can grow on soils with loam, sand, clay or other types of soils with a poor fertility. It grows the best when planted in full sun but tolerates partial shade as well. As for the required soil pH, this should be around 6 for acidic soils, 6 to 8 for neutral soils, or 8 in the case of basic soils. The plant is tolerant of drought but should be provided with plenty of water in order for the fruits to have a good quality.
Rubus parviflorus can be found on a wide range of elevations in its native range, from sea level in the north up to 2500 m in the south. It is a perennial species that is well adapted to various climates. It tolerates light frost but persistent temperatures below -2 °C will kill the plant. For propagation, both the seeds and partial rhizomes can be used.
Collection and harvesting
The fresh fruits are extremely delicate and must be consumed in the same day after they are harvested. If you want to eat them fresh, timing is essential. Their soft texture makes harvesting a difficult task, which should be done with care. The berries don’t ripe all at the same time, so the same shrub can be harvested over the course of several weeks.