This article was published in the Titirangi Tatler, June 2011
Possibly the most widely recognized tree in the New Zealand forest, rimu was one of the first trees collected by Captain Cook on his first voyage to New Zealand. His botanist, Solander, created the genus Dacrydium specifically for rimu. The name refers to the exuded resin which weeps from the tree, but I like to think it also recognizes the striking, weeping foliage that makes rimu so distinctive.
The 8 other New Zealand species that were first included in Dacrydium have recently been transferred to other genera leaving rimu as the sole New Zealand representative along with 15 others from New Caledonia, Fiji, the Solomon Islands, New Guinea, Indonesia, Malaysia, the Phillipines, Thailand and China. That range clearly shows the tropical affiliation of rimu and the fact that seed are bird-dispersed to distant regions.
These days the birds associated with rimu in the Waitakere Ranges are woodpigeon and tui. But we need to foresee the day when other bird species are common in the Waitakeres and start planting trees to provide their favoured foods. Rimu fruit are the food of choice of several species no longer naturally in the ranges. Bellbirds are coming in their own good time, having returned to the Northland coastline from Little Barrier over the last few years. Kokako have been introduced into the Waitakeres and are showing every sign of settling in for the long haul. Nesting in the Ark in the Park project has been successful and the fledglings are healthy. What is the long term future for these birds and their descendants? Assuming pests can continue to be controlled, or better still eradicated, the expanding populations of kokako and bellbird are not assured of a secure future if it is limited by lack of appropriate food sources. Rimu fruiting has been shown to be an important trigger for bird nesting and it is critical that we create suitable habitat for the increasing bird numbers. Just imagine - if we had enough rimu around town we could introduce kakapo to the suburbs. It pays to dream.
If you have room for a 10m - 20m tall tree, consider a rimu. To achieve the best fruiting it is necessary to have both male and female trees in moderately close proximity. If you don't have room for two, persuade someone in the street to also plant one. The wind-blown pollen can span kilometres of separation but is more effective within tens or hundreds of metres. Of course determining if a young seedling is male or female is nigh impossible until it flowers, so then you need to persuade more neighbours to plant more rimu. Which is good for the nurseryman but even better for the environment.