Our native members of this genus have become so ubiquitous that it could be easy to be dismissive of them – as a sort of horticultural panacea that is trundled out in the absence of other ideas. However, a good plant shouldn’t be dismissed just because it has become a standard.
Both of our native species are popular for their outstanding qualities; not least, the vibrant hue of their leaves. They form excellent structural shrubs (or small trees, depending on whether trimming is applied), and may be used in a variety of ways (although they are most often used for hedging).
The image below shows Griselinia littoralis, the most frequently-planted species, growing wild in the Hooker Valley (near the foot of Mt Cook). It pays to take note of the montane habitats in which G. littoralis is commonly found, as this goes some way to explaining why large numbers of this species unceremoniously turn up their toes in Auckland’s climate – following dry summers, where the extra factor of high humidity can prove the killer blow to a plant that is more at home within southern climes. Humidity is somewhat mitigated as a factor by continual air movement, and therefore open, coastal areas are the most appropriate situations in which to grow this species in northern New Zealand.
Other than a relatively small number of plants at a cool, high point in the Hunua Ranges, Griselinia littoralis is not naturally found in the Auckland region. In my opinion, landscapers and gardeners wishing to plant Griselinia in the north should look more to the larger-leaved G. lucida, which is a relatively common component of northern forests.
Where plants of Griselinia are to be cultivated for their ecological value, it is worth considering one aspect of their reproduction (of which Geoff Davidson reminded me). Both species are dioecious, meaning that male and female flowers occur on different plants. Accordingly, if one just plants specimens of a named variety, they will be sterile – thereby, producing neither fruits nor progeny.
There are six species of Griselinia that are divided between Chile and New Zealand. Both of our native species are confined to New Zealand’s shores. The genus was named for Francesco Griselini, an 18th Century natural historian from Venice.
There is something rather extravagant about the way in which Griselinia lucida perches in the canopy of other trees – a flamboyant guest stealing the limelight from its hosts. Akapuka is one of many plants that gain access to light, pollinators and nutrients atop some of our largest trees. It commonly gets a start on asteliad nests (notably of Astelia solandri and Astelia hastata) that establish in the forks of trees, thereby providing stable platforms (as well as water and nutrients) for species like G. lucida.
Akapuka also finds a suitable home on rocky ground, including the lavafields found on Rangitoto Island and a few parts of metropolitan Auckland, and on rocky outcrops like the one pictured above (on the coastline between Karekare beach and Whatipu). Depending on where it finds itself, G. lucida can grow as a compact shrub to a small, spreading tree, over a wide size range between 1m to 8m tall. However, in normal growing conditions, it reaches about 4m in height with an equivalent width.
One remarkable feature of this species is the appearance of the long roots that it sends down towards the ground from its position within the canopy. When these strange, longitudinally grooved roots reach the forest floor, plants of G. lucida gain a direct line to increased water and nutrients (similar to the strategy of northern rata, except that akapuka does not supersede its host, opting to remain as a guest).
Unsurprisingly for a species with such striking and attractive foliage, Griselinia lucida was collected by Joseph Banks and Daniel Solander on Cook’s first voyage to New Zealand in 1769. The specific epithet ‘lucida’ refers to the vibrance of the leaves.