One of the main evergreen forest trees of New Zealand, rimu trees can live as long as 800 years. The small fleshy seed capsules are eaten by both birds and terrestrial rodents that spread the seed across the landscape. The extent of rimu forests is diminishing because of logging and seed destruction by non-native animals. You can grow this tree in mild temperate climate regions in U.S. Department of Agriculture hardiness zones 8 through 11.
Rimu is a gymnosperm, or non-flowering plant, that bears its naked seeds in cones, making it a conifer. Botanically it is grouped into the podocarp family, Podocarpaceae. Rimu's botanical name is Dacrydium cupressium. An old, no-longer-used synonym is Thalamia cupressina.
According to the Encyclopedia of New Zealand, rimu is the most widespread of all New Zealand forest trees, occurring throughout the North, South and Stewart islands from lowlands to montane forests. On the South Island in particular, rimu is often called red pine.
Reaching mature heights of 100 to 150 feet, rimu develops a pyramid-like crown when young, with pendulous branches and foliage. With greater age, the crown becomes more rounded, with strong horizontal branches with drooping masses of leaves. The grayish-dark brown bark is stringy and dimpled, peeling away in long thick flakes. The juvenile leaves are tiny and keel-shaped, wrapping around the twigs to cloak them in green. Older, "adult" leaves are shorter and rigid. In the winter the leaves blush bronze.
Rimu trees are either male or female in gender, and can be differentiated by their cones. Small, light green pollen cones occur on male trees either alone or in pairs at branch tips. Female cones are reduced to a small cluster of scales and an inverted ovary on an curved branchlet on branch tips. Female cones occur singly, and look like a succulent, red-tinted receptacle of "fruit." Once pollinated by the wind, the seeds take up to one year to ripen. The female cones produce seeds in irregular intervals, such as every five or six years, according to The Gymnosperm Database.
Easily grown from seed, rimu trees need a partially shaded location in their youth but acclimate to full sun as they grow skyward. Locate it in a wind-protected, humid spot where the soil is moist and fertile, and not alkaline in pH. Organic mulch helps conserve soil moisture in the heat of summer as well as provide trace nutrients for the roots.
This is one of the most popular New Zealand trees for ornamental use in gardens around the world. Rimu is a timber tree in its homeland, providing a dense wood that is red, hard and durable. Beautiful figuration within the heartwood makes it highly prized as a finishing product for doors, door frames, paneling and furniture. Traditionally the wood was used extensively for house frames and weatherboarding. The bark contains tannins and provides a reddish color to leather. Captain James Cook brewed a "spruce tea" from young rimu shoots and sugar in 1773, according The Gymnosperm Database.