Ambitious daisies

April 2, 2021

Not all daisies conform to what we usually imagine when we think about this versatile family of plants. In stark contrast with bucolic visions of meadows flecked with white and yellow discs, some daisies are just weirdos – albeit delightful weirdos. The Pomahaka tree daisy (Olearia fimbriata) is one of a number of botanical miscreants from southern parts of NZ that have eschewed showiness in favour of a sturdier (and more subtle) approach to existence.

In late spring of 2020, I visited an area in northern Southland in which significant wild populations of this nationally threatened small tree remain within a matrix of wooded areas, shrubland and farmland (in broad, rolling hill country between Waikaia Forest and Central Otago).

My professional interest in O. fimbriata and several of its relatives is based on a number of attributes; including their expressive branching structures, the subtle, smoke-like character of the foliage, their scented flowers, and the wildlife value offered by multiple species of small-leaved tree daisies (notably as home to a number of moths that only live on this cohort of Olearias).

The images above show a grove of Olearia fimbriata on a grazed hillside, which was growing in close association with another threatened tree daisy, Olearia hectorii (in images further down within this journal entry). The picture on the right provides a moth’s-eye view of the fissured bark on a particularly large Pomahaka tree daisy – which constitutes one of several niches that a single tree offers to distinct moth species.

The bark on Olearia hectorii is much more deeply grooved than O. fimbriata, as illustrated above, whilst the larger, pale green foliage also serves to distinguish this impressive species. On the first occasion that I saw O. hectorii in the wild (in Marlborough), I was struck by the similarity of its overall form and foliage texture to willow trees – an impression that was reinforced by the groves of both aforementioned species in this part of northern Southland.

Although this landscape now presents a very different face to the mosaic of habitats that would have once occurred here, these 2 rare tree daisies still offered clues to their role within the wider landscape (and their habitat preferences). In common with several other rare native trees, O. hectorii and O. fimbriata favour areas where water generates disturbance (including the hillside on which the groves pictured herein were positioned) – somewhat similar to willow carr’s association with damp habitats in European landscapes.

Water tracks a path in surprising ways through hill country like that pictured below – with folds in hillsides directing water through naturally terraced slopes, and moisture often accumulating in damp habitats perching on the brow of these hills.

A much smaller-growing Olearia (O. bullata) is closely associated with seeping banks like the one pictured below, where this distinctive species really does look like rounded clouds of smoke.

Before we embarked on this trip, I was unsure of whether I was going to be able to distinguish Olearia bullata from other small-leaved Olearias. As it turns out, I need not have worried as the narrow, puckered (or bullate) leaf clearly marks this horticulturally valuable species out from its near-relatives.