It is the non-lignotuberous arborescent form of the species, which occurs between Geraldton and Shark Bay, and in the Kennedy Ranges.

It grows as a tree or shrub up to seven metres in height, and lacks a lignotuber.

boreoscaia, which is a lignotuberous shrub that reaches no higher than two metres.

ashbyi occurs in two disjunct populations: between Geraldton and Shark Bay, and around 400 kilometres further north in the Kennedy Range.

[1] Although distinct lignotuberous and non-lignotuberous forms of B. ashbyi had long been recognised, they were not formally described as taxa until 2008, when Alex George published the lignotuberous form as B. ashbyi subsp.