Rimu

Dacrydium cupressinum

Name: Dacrydium cupressinum; with common names of rimu, red pine, huarangi, puaka or Southern conifer, and belonging to the Podocarpaceae family. Rimu is a very tall canopy tree that is found in forests throughout the North Island and the coastal areas of the South Island, predominately the north, east and south areas. Rimu is a well known timber tree as well as being used in Rongoa, Maori medicine.

Identification and cultivation: Rimu is an emergent tree that is found within the canopy of New Zealand’s forests. Rimu trees grow slowly, reaching an age of 800-900 years old. The rimu tree dates back 70 million years, to the Podocarp forests that used to dominate the New Zealand landscape. The trees can grow to a height of 20-35m with some ancient specimens growing to a height of 60m and a trunk diameter of 1.5m. However, in older trees this may be wider.

Rimu has be described as a graceful tree; it is noted by its drooping, flaky bark that is deep red in colour, and its swinging branchlets. The juvenile tree is open-branched with pale green foliage. As the tree matures it becomes pyramidal in shape, sometimes producing seeds; the tree retains this structural type for many years. The fully mature tree has a straight trunk with long lateral branches, the lower branches of the tree atrophying and falling away.

The leaves overlap and are narrow and elongated, feeling soft and pliable on young trees. These leaves are 7mm by 1mm in dimension. As the tree matures, the size of the leaves diminishes, finally becoming 3-4mm by 1mm in dimension; they are more triangular in appearance and rigid in manner.

Rimu is a dioecious tree with male and female cones on different trees; these, when fertilised, take 15 months to become bright red in colour, containing seeds, which make a valuable food source in the forest. Birds spread the seeds through their droppings (Salmon, 2001).

Parts Used: Berries (cones), leaves, twigs, gum and inner bark.

Harvesting: The berries, once fertilised, take 18 months to mature, turning from red to black. This means that the rimu produces a plentiful supply of fruit every other year. The berries were traditionally harvested by Maori by shaking them into containers or blankets.

Energetic Character: Astringent.

Constituents: There is limited information on rimu’s chemical constituents. It is an antiscorbutic, which means it prevents scurvy, therefore contains significant amounts of vitamin C.

Essential oils: Lauren-1-ene, sclarene, abietatriene, (+)-α-longipinene, (+)-longifolene, (-)-caryophyllene, (-)-carophyllene oxide, humulene, (-)-α-selinene, (+)- β-selinene, β-elemene,δ-elemene, (+)-longibornyl acetate, (-)alloaromadendrene, (+)-9βH-caryophyllene.

Leaves: Amentoflavone, hinokiflavone, amentoflavone 4′-monomethyl ether, amentoflavone 7,4′-dimethyl ether, amentoflavone 7,4′, 7″,4′”-tetramethyl ether, unidentified biflavonoid

Leaves twigs and bark: Phenolic glycoside, tannins, sequoyitol, totarol, β-sitosterol, leucocyanidin, dacrysterone, ponasterone (Cambie, 1988).

Medicinal Uses:

Internal uses: Captain Cook’s crew were reported to have made beer from the leaves and twigs of rimu and manuka. This reportedly was an antiscorbutic.

A walnut size piece of gum is dissolved in water then a tablespoon taken three times a day to allay the bleeding of lungs, bowels, stomach or headache (O’Carroll, 1881).

Gum is used as a styptic to stop bleeding wounds (Baber, 1887).

External uses: Bark is used for healing ulcers or running sores (Taylor, 1848).

Rimu is used for bruises, dislocation, fractures and sprains (1890).

Tooth powder made from rimu heartwood was used to remove taiaakiaki, the discolouration of teeth (Best, 1911).

Rimu leaves are used on skin sores (Moore, 1940; Riley, 1994).

Cautions and Contradictions: Excessive consumption of the raw berries is reported to cause constipation.

Dosages: Decoction: Boil 1 teaspoon of bark in 1 cup of water for 30 minutes or dissolve the gum (1” cube) with 300ml water. Take 1 tablespoon three times a day.

Tincture: 5-20ml per week or ¼ teaspoon twice daily of a 1: 5 extraction.

Alternatively; potentise to 1x or 10-40 drops per 100ml (Phytomed, 2018; Riley, 1994).

Culinary/Medicinal Uses: Much of the information about the uses of rimu are from historical accounts. Many of rimu’s properties appear to be for the healing of skin problems, stomach ailments and bleeding conditions. Teas of rimu have also been reported to work in a similar manner.

Other Uses: Rimu is a much valued timber; Maori used it to produce long spears – these were used for personal defence and to defend pa sites.

History and Mystery: The bark of the tree was often used for the production of fires, rimu wood being reputed to produce little smoke and an unusual smell – the Maori people believed the wood could help keep away evil spirits, particularly, at night.

Rimu was also used in traditional Maori tattoos (moko). The grub aawhato is found near the roots of the rata tree; this and the heartwood of kauri, kahikatea or rimu were burnt and ground to powder by stone; this was then used as a pigment for the moko.

Rimu has been used extensively in construction; many buildings and furniture are produced from the long straight trunks of the tree. The red colour of the wood often stained the timber workers, therefore often the lowest paid workers cut rimu at the mill.

Rimu is linked with the stories of the forest. It’s gum, sap and wood are red in colour. Maori tradition reports this is because the tree absorbed the blood of the monster Tunaroa who was killed by Maui (Riley, 1994).

References:

1. Cambie, R.C. (1988) ‘A New Zealand phytochemical register’, Journal of the Royal Society of New Zealand, 18: 2, pp. 159-160.
2. (2018) Dosage Chart – Fluid Extracts and Tinctures.
3. Riley, M. (1994) Māori healing and herbal: New Zealand Ethnobotanical Sourcebook., Paraparaumu: Viking Sevenseas.
4. Salmon, J.T. (2001) The Native Tree of New Zealand, Auckland: Reed Books.

Prepared by Karen Pearson for the Herb Federation of New Zealand’s Herb Awareness Week 2019

Advisory Note: This text is given a general guidance. If any adverse reactions occur or symptoms persist, please contact a qualified medical herbalist or doctor immediately.