TARN

 Low, dense, mounding shrubs are a mainstay of many gardens globally, due to their ability to create structure in a garden (whether informally or formally). This category of plant is not well represented in the Sydney flora, where most shrubs are open, straggly or diaphanous. Yes, there is the commonly used coastal rosemary (Westringia fruticosa), but its grey tone and preference for sun makes it unsuitable in some conditions. Yes, the coastal heathlands around Sydney are replete with dense mounding forms, but in a garden setting most of these species will be unleashed from the shackles of cliff-line winds and narrow skeletal soil profiles and become leggy and unstructured at best.

Due to the lack of dense shrubs (and other reasons also), the Australian horticulture industry as developed many cultivars of native shrubs and trees, selecting and breeding them to have more more bushy, dense and/or dwarf characteristics than the naturally occurring species.

However, our preference is always to favour local, naturally occurring forms over cultivars, for a number of reasons that require their own essay. Therefore, we are always hunting for potential low dense shrub species. There are several species we are exploring for this growth habit, such as species in the genera Austromyrtus, Prostanthera, Tristania, Leptospermum, Pittosporum, Baeckea and alternative Westringia species. Another is the subject of the profile, Acrotriche divaricata.

A very attractive species with needle-like leaves we have seen this species in the wild in two extremely different conditions: a perpetually wet rainforest gully in the Royal National Park (along Forest Path near the Hacking River) and a dry, sunny exposed coastal headland in Pittwater (Woody Point).

Interestingly, the common feature of both sites is that the soils are derived from eroded Narrabeen Group geology, and composed of intermingled colluvial deposits of shale and sandstone.

Acrotriche sits within the family Ericaceae (a group that includes epacris, blueberry, rhododendron and heather). The Australian members of Ericaceae (subfamily Epacridoideae) are notoriously hard to grow due to microbial interactions in the soil that are still somewhat unclear. But I have some hope that this species might be different, due to it being found in conditions that are quite unlike where most Sydney Ericaceae are found.

I’m yet to see it in a garden or nursery. Please email me if you have, I would love to get my hands on some!