Boronia inornata

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 : 97

Placement of Boronia inornata and B. coriacea

Boronia inornata is found in south-western Australia and one of its two subspecies is also found in South Australia. The species has large hemispherical glands on the branches (unusual but not unique in Boronia , see B. algida (section Algidae ), B. microphylla Sieber ex Rchb. (section Boronia ) and B. bowmanii F.Muell. (section Valvatae ), for example), imparipinnate leaves with 3(5) usually terete leaflets, terminal inflorescences of 1(–3) flowers, and the seeds are microscopically tuberculate and do not have the sunken hilum that is typical of section Boronia . In all analyses, B. inornata , which is represented by numerous samples, forms a robustly supported clade (1.00 PP, 100 JK, Fig. 1 ) sister to the south-western Australian B. alata Sm. + B. corynophylla clade in the combined ( PP 0.98) and nuclear Bayesian analyses.

Boronia coriacea is currently placed in section Boronia ( Wilson 1971; Duretto et al. 2013; Bayly et al. 2015). Bayly et al. (2015) indicated that B. coriacea may be related to B. inornata and both species have glandular verrucose stems, leaves that are 3(5)-foliolate, terminal inflorescences with few flowers, imbricate sepals and petals, petals with an obscure apiculum on the abaxial surface, and glabrous stamens. The two species differ in that B. inornata has leaflets that are usually terete and flowers that are usually solitary on short pedicels, whereas B. coriacea has flat leaflets, and an inflorescence of a few flowers that are on longer pedicels. The seed morphology of B. coriacea has not been documented, and Wilson (1971), who described the species, and Duretto et al. (2013), in the Flora of Australia, do not discuss its relationships. The features these two species share are not unique in Boronia , but the combination is. Apart from the aestivation of the petals the species are similar to B. algida (section Algidae ) in appearance. Boronia inornata does not group with any species of section Algidae in our analyses.

Boronia inornata is isolated from all other species in this analysis and a new section, section Inornatae Duretto & Heslewood , is formally described below to accommodate it. As B. coriacea is morphologically similar to B. inornata , it is also placed in this newly described section.

Figures

Fig. 1. Bayesian 50% majority-rule consensus tree from the combined analysis of two nuclear (ITS, ETS) and three plastid markers (psbA–trnH, trnL–trnF and rbcL), with thick lines showing supported clades (≥0.95 PP). Jackknife percentages from MP analysis are indicated with symbols above branches: 100% JK (closed triangle); 90–99% JK (closed circle); 75–89% JK (open triangle); 50–74% JK (open circle). New or revised sectional assignments are indicated in bold. Section Boronia clade has been collapsed and is shown in detail in Fig. 2.