Common Name: Rimu

General Information

Dacrydium cupressinum is an evergreen tree with a crown that is pyramidal when young, becoming round-topped with strong lateral branches as it matures; it can grow 20 - 35 metres tall, occasionally reaching 55 metres. The straight, cylindrical bole can be 150cm or more in diameter on mature trees[].
Rimu used to be one of the major timber trees of New Zealand, but is at present (2017) the wild stock is protected from exploitation. Traditionally, the tree was also harvested from the wild as a source of food and materials. It is sometimes grown as an ornamental.
This species, and its main forest type, has undergone a significant decline over the last several centuries. However, the majority of this decline pre-dates the period of this assessment. In the absence of any current or ongoing decline the plant is classified as 'Least Concern' in the IUCN Red List of Threatened Species(2013)[].

Known Hazards

None known

Botanical References

, 200,

Range

New Zealand - North, South and Stewart Islands

Habitat

A canopy or emergent tree in lowland and montane forests; at elevations to 800 metres[, ].

Properties

Conservation Status	Least Concern
Edibility Rating
Habit	Evergreen Tree
Height	30.00 m
Growth Rate	Slow
Pollinators	Wind
Self-fertile	No
Cultivation Status	Wild

Cultivation Details

Dacrydium cupressinum Within its range, mean annual temperature is 10.4°C, with an average minimum in the coldest month of 1.2°C, and a mean annual precipitation of 2633 mm[]. (cold hardiness limit between -6.6°C and -1.1°C[].
Requires a light, freely draining soil in a sheltered position with protection from cold winds[]. Requires high rainfall and humidity if it is to succeed. It tolerates shade and probably requires it in drier areas if the tree is to survive. Requires warm humid summers and mild humid winters if it is to grow well, and even then it is very slow growing[]. It is best grown in a woodland garden[].
This species is only hardy in the very mildest areas of the country and does not really thrive even there[, ]. A tree on the Scilly Isles was 9 metres tall in 1970[]. Seed from a more alpine provenance might be more successful[].
A dioecious species, both male and female forms must be grown if fruit and seed are required[].

Logging and forest clearing have reduced the population historically, these activities have now ceased. Due to changes in land use which are permanent, the population became fragmented, although not severely fragmented in an IUCN sense. Regeneration is causing the population to increase again[].
A dominant or codominant emergent in mixed conifer (podocarp) forest or conifer-angiosperm forest at low to middle elevations up to 700 m a.s.l. These forests are (warm) temperate evergreen rain forests with year-round high precipitation and are multi-layered with emergent conifers, a canopy of conifers and/or angiosperms, an understorey of shrubs, tree ferns and palms, and a ground cover of ferns and mosses. In the kauri forest of Northland D. Cupressinum is a minor component, but in other forest types it is often the most common species, sometimes occurring in nearly pure stands. Very large specimens may be around 1,000 years old, but few of these survive today in only remnants of a once extensive native lowland forest cover[].
Due to severe depletion of this natural resource, exploitation has been halted and this species is now protected from logging by law. As a slow growing tree it is not considered suitable for plantation forestry and it finds only limited use as an amenity tree in gardens and parks, mainly in New Zealand[].
regeneration takes place continually beneath an intact forest canopy. Initially very large numbers of seedling are produced, which experience very high mortality within a few years. The surviving sapling and small trees may persist beneath the canopy for 100 to 400 years, during which time they grow exceedingly slowly. When a gap-phase event such as windthrow or death of an overstory tree creates a localized opening in the canopy, the pole-size trees may be able to exploit the improved light environment and finally become canopy codominant trees[].

Edible Uses

Fruit - raw or cooked[, , ]. It can be somewhat constipating[].

A resinous substance from the young branches has been used to make an alcoholic beverage resembling spruce beer[]. The resin is bitter but edible[].
In March 1773 (on his second voyage), Captain James Cook stopped in Dusky Sound to brew a beer he called a spruce beer, intended to combat scurvy, made from sugar (treacle or molasses) fermented with young rimu shoots (Salmon 1996). Such beers, made with young spruce (Picea) shoots, were commonly used for the purpose in England and the New World, due to the high vitamin C content of the young shoots[].

Medicinal

The cones are rich in bioavailable calcium and vitamin D. The kakapo (Strigops habroptilus), a highly endangered parrot endemic to New Zealand (and the heaviest parrot in the world), has been found to breed successfully only during D. cupressinum mast years. The vitamin D is in the D3 form, formerly thought to be produced only by animals, more recently discovered to be produced by some plants in the Solanaceae; this is the first report of it being produced by a conifer (von Hurst et al. 2016)[].

Other Uses

The heartwood is extremely resinous and is used as a torch[].

The bark is a rich source of tannin[, , ].

The deep red coloured wood is strong, hard and durable[]. Beautifully marked, it is much used for construction, railway sleepers, furniture etc[, , , , ].
Rimu or Red Pine was, when exploited, the major timber tree in New Zealand as it was ubiquitous throughout the lowlands of the major islands and attained large sizes. The wood is reddish brown in colour, often finely figured and very durable and strong. It was used in general construction, for bridges, railway sleepers, fence posts, indoor flooring and panelling, and furniture. The most decoratively figured pieces were reserved for cabinet making[].
The heartwood is nearly always beautifully figured, as a result of the grain being twisted during growth. Heart rimu is one of the most beautifully figured woods in the world, and for this reason has always been highly prized in New Zealand as a finishing timber for doors, door frames, panelling and furniture[].

Propagation

Seed - sow spring in a freely draining compost[]. It usually germinates in 1 - 3 months at 20°c[]. Another report says that the seed can be very slow to germinate and that it is best sown in a cold frame as soon as it is ripe[]. When they are large enough to handle, prick the seedlings out into individual pots and grow them on in the greenhouse for at least their first winter. Plant them out into their permanent positions in late spring or early summer, after the last expected frosts.
Cuttings of short leading shoots in early autumn[].