February 26, 2018

Whilst New Zealand prepared for a comprehensive census of the human populace, we recently undertook the much simpler task of performing an informal census on the tiny remaining population of a critically endangered herb, Parahebe jovellanoides, which endures in a forest remnant near Riverhead (to the northwest of Auckland).

Considering as the area occupied by this intriguing little plant (whose relatives all live far south from here) is in the region of 20 to 30 square metres, our efforts were hardly heroic, but it was good to see that it appears to have remained stable in its own known natural population in the years since I visited this forest with Geoff Davidson.

Parahebe jovellanoides (pictured above) wends its way through the undergrowth amidst tree fern fronds and other detritus in a reserve that is notable for the prevalence of several species associated with much colder areas. Accordingly, P. jovellanoides is not the only unusual feature of this forest. Plants such as the tree fern, katote (Cyathea smithii), or black maire (Nestegis cunninghamii) are rare this far north, whilst a creeping herb, Nertera villosa, is a very surprising inhabitant for our region.

As can be seen above and below left, the reserve borders a beautiful river that not only sets the tone visually (establishing an ethereal atmosphere), but also regulates the environment around it – such that attractive plants like the zig-zagging small tree, Melicytus micranthus, and a tiny native iris, Libertia micrantha, find suitable conditions to grow here. Large colonies of crown fern (Blechnum discolor) clothe the riverbank in some parts (as pictured below), where their vibrant, light green hue illuminates the forest understorey.

On the afternoon that we visited the forest, the play of light and shadow highlighted the form of a native broom (Carmichaelia australis) in a way that made it appear to float above the river (as shown below). By isolating it out from the green clamour of its surroundings, the shaft of light that landed upon the broom demonstrated its very structured growth form – alluding to how it might be used in plantings.