Boronia Sm. section Boronia

Duretto, Marco F., Heslewood, Margaret M. & Bayly, Michael J., 2023, A molecular phylogeny of Boronia (Rutaceae): placement of enigmatic taxa and a revised infrageneric classification, Australian Systematic Botany 36 (2), pp. 81-106 : 103

Boronia Sm. section Boronia

Type: Boronia pinnata Sm.

Hairs simple. Branchlets, including cortex, not articulated (continuous) at nodes, smooth or glandular–verrucose, glabrous or hairy. Leaves opposite–decussate, simple or imparipinnate. Inflorescence axillary or terminal, flowers solitary or in cymes, 1–40+-flowered; peduncle absent or present; bracts and bracteoles persistent. Sepals open or imbricate in bud, persistent. Petals imbricate in bud, with subterminal apiculum on the abaxial surface, multiveined from base or with steeply ascending basal lateral veins. Staminal filaments glabrous or hairy, swollen and usually verrucose, rarely smooth, towards apex, with tip usually appearing subterminal adaxially. Stigma minute and scarcely wider than style or massive. Seed with a smooth sclerotesta, cell walls not usually visible, glossy; hilum adaxial, linear, usually in a groove with labiose margins; raphe small and covered by brown outer testa; cotyledons linear, as wide as hypocotyl.

A section of 43 species found across southern Australia, including Tasmania, with 24 species confined to south-eastern Australia and 19 to south-western Australia. The section outlined here is equivalent to that described as section Boronia by Bayly et al. (2015) less B. coriacea , and Boronia ser. Boronia by Duretto et al. (2013), less B. coriacea , B. inornata , B. humifusa , B. ovata and B. scabra . A key to the species is provided by Duretto et al. (2013). No novel species for the section have been formally described since Duretto et al. (2013) though B. clavata has recently had novel subspecies formally described ( Duretto 2019).

Here we present a novel infrageneric classification of the section that includes four series, including one newly described and two reinstated.

Key to the series of Boronia section Boronia

1. Staminal filaments woolly; leaves simple...............series Variabiles

Staminal filaments pilose, puberulous or glabrous; leaves simple or imparipinnate...............................................................................2

2. Petioles persistent or tardily caducous and after lamina has fallen; leaves imparipinnate; anthers approximately equal or antisepalous anthers much smaller than antipetalous anthers............................ .............................................................................series Persistens

Petioles absent or deciduous with leaves; leaves simple or imparipinnate; anthers approximately equal or antisepalous anthers much larger than antipetalous anthers.........................................3

3. Leaves simple...................................................................................4

Leaves imparipinnate.......................................................................6

4. Inflorescence terminal, often also in upper axils........series Boronia

Inflorescence axillary.......................................................................5

5. Leaf margin smooth (Qld, NSW)................................series Boronia

Leaf margin crenulate ( SW Austr.)......................series Heterandrae

6. Inflorescence axillary, or axillary and terminal, 1–40 + -flowered; peduncle up to 30 mm long; antisepalous and antipetalous anthers approximately equal ( SA, Qld, NSW, Vic., Tas.)......series Boronia

Flowers axillary, solitary or in pairs, or rarely in threes; peduncle absent or minute; antisepalous approximately equal to or significantly larger than antipetalous anthers ( SW Austr.)...................... .........................................................................series Heterandrae