Rimu is a slow-growing tree, eventually attaining a height of up to 50 m, although most surviving large trees are 20 to 35 m tall. It typically appears as an emergent from mixed broadleaf temperate rainforest, although there are almost pure stands (especially the west coast of the South Island). There are historical accounts of exceptionally tall trees, 61 m, from dense forest near National Park, New Zealand, now destroyed [2]. Its lifespan is approximately 800 to 900 years. The straight trunk of the rimu is generally 1.5 m in diameter, but may be larger in old or very tall specimens.

Trunk of a rimu with rata (Metrosideros) vinesThe leaves are spirally arranged, awl-shaped, up to 7 mm long on juvenile plants, and 1 mm wide; and 2 to 3 mm long on mature trees.

It is dioecious, with male and female cones on separate trees; the seeds take 15 months to mature after pollination. The mature cones comprise a swollen red fleshy scale 6 to 10 mm long bearing one (rarely two) apical seeds 4 mm long. The seeds are dispersed by birds which eat the fleshy scale and pass the seed on in their droppings; they are an important food resource for some species, particularly the kakapo, whose breeding cycle has been linked to cone production cycle of the tree.

Historically, rimu and other native trees such as kauri and totara were the main sources of wood for New Zealand, including furniture and house construction. However, many of New Zealand’s original stands of rimu have been destroyed, and recent government policies forbid the felling of rimu in public forests, though allowing limited logging on private land. Pinus radiata has now replaced rimu in most industries, although rimu remains popular for the production of high quality wooden furniture. There is also limited recovery of stump and root wood, from trees felled many years before, for use in making bowls and other wood turned objects.