Blue boronia

Appearance

''Boronia coerulescens'' is an erect shrub that grows to a height of 0.2–0.6 m with branchlets that are warty glandular. The leaves are usually simple, more or less cylindrical in shape to narrow oblong or elliptic, 5–10 mm long and 0.5–1.5 mm wide.

The flowers are bright blue, lilac-coloured or white and are arranged singly in leaf axils or in dense, leafy spikes on the end of the branches. Each flower has a pedicel 2–5 mm long. The four sepals are triangular to broadly egg-shaped, 1.5–7 mm long with their bases overlapping.

The four petals are more or less egg-shaped with a small, pointed tip, 3–9 mm long with their bases overlapping. The eight stamens and the style are slightly hairy. Flowering mostly occurs from August to November and the fruit are 3–4 mm long with the petals remaining on the end.

Naming

''Boronia coerulescens'' was first formally described in 1854 by Ferdinand von Mueller and the description was published in ''Transactions of the Philosophical Society of Victoria''. The specific epithet is a Latin word ''caeruleus'' meaning "sky blue" with the ending ''-'' signifying "beginning of" or "becoming".:135

There are three subspecies:
⤷  ''Boronia coerulescens'' subsp. ''coerulescens'' that has flowers in leaf axils;
⤷  ''Boronia coerulescens'' subsp. ''spicata'' that has flowers in dense, leafy, spike-like racemes;
⤷  ''Boronia coerulescens'' subsp. ''spinescens'', originally described in 1863 as ''Boronia spinescens'' by George Bentham, is a variable subspecies with spreading, often pungent branchlet and is similar to subspecies ''coerulescens''.

Distribution

Blue boronia grows in mallee woodland. Subspecies ''coerulescens'' occurs in the south-west of Western Australia, in South Australia, Victoria and in the far south-west of New South Wales.

Subspecies ''spicata'' occurs in Western Australia between Wubin and Muntadgin and ''spinescens'' is found in similar areas to subspecies ''coerulescens'' but only in Western Australia.

Status

All three subspecies of ''B. coerulescens'' are classified as "not threatened" by the Western Australian Government Department of Parks and Wildlife.