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Synonyms: Plectranthus parviflorus Willd. APNI*

Description: Prostrate to semi-erect, semi-succulent to herbaceous, suffrutescent subshrub up to 0.7 m high, with a distinct fleshy tuberous base (to 30 mm diameter) on seed-derived plants only (i.e., not a ramet). Coloured sessile multicellular glands 8-celled and orange. Branches with short retrorse, non-glandular hairs, moderately to densely distributed; glandular hairs occasional to rare. Producing a pungent smell when touched or crushed (at least on inflorescence and flowers).

Leaves variable depending on environment, appearing dull green and discolorous when sheltered, and nitid, reddish or yellowish green, and more succulent in exposed, drier areas; petiole 5–55 mm long; lamina circular-ovate to ovate or oblong to ovate, 15–90 mm long, 10–60 mm wide; apex obtuse or acute, base broadly cuneate to subtruncate, margin dentate or crenate with 4–8(–12) pairs of teeth; upper surface flat or with veins distinctly sunken, indumentum sparse to moderately to dense, and orange sessile multicellular glands occasional; lower surface with veins slightly raised, sparsely pubescent, glandular trichomes occasional, and orange sessile multicellular glands densely distributed.

Inflorescence up to 150 mm long, consisting of up to 3(–7) racemose branches; verticillasters (6–)10-flowered. Pedicel 1–6 mm long. Calyx 1.4–2.6 mm long. Corolla 6–11 mm long, pale mauve to white with blue-violet markings on lateral lobes; tube 1.2–3.2 mm long, curved downwards (0°–)10°–40°. Stamen not extending past lower corolla lobe, pollen white. Style meeting or slightly extending past lower corolla lobe. Cleistogamous flowers superficially appear as unopened buds, however the white corolla extending just past the calyx never opens.

Fruiting calyx accrescent, 3.7–5 mm long. Mericarp glossy dark brown to black, 0.7–1 mm long, 0.7–0.9 mm wide, subcircular in outline.

Habit Photo L. von Richter

Flower Photo L. von Richter

Fruit Photo L. von Richter

Flowering: Cleistogamous flowers can be produced throughout the year. Chasmogamous (i.e., outcrossing) flowers typically appear between November and April.

Distribution and occurrence: This species is currently recognised in eastern Australia (Victoria, New South Wales and Queensland), New Zealand and Hawai’i.

This species grows in a variety of habitats that are at least somewhat exposed to direct light. This includes rocky outcrops, scree slopes, embankments and riparian zones, at altitudes to 1,200 m, in forests, rainforest margins, woodland, coastal heathland, and mesic to semi-arid shrubland.
NSW subdivisions: NT, CT, ST, NC, CC, SC
Other Australian states: Qld

AVH map***

This species has been commonly confused with most NSW species, including C. cremnus, C. nitidus, C. suaveolens and C. graveolens. Morphological plasticity, wide distribution, a wide variety of preferred habitats, and a complicated taxonomic history have all made C. australis one of the most problematic Coleus to identify in Australia. It occurs with other nearby other Coleus species, including C. suaveolens, C. cremnus, C. graveolens, and currently undescribed species in NSW. Unpublished results based on molecular data and observations substantiate the capacity of this species to hybridise with these taxa; intermediate forms of these hybrids have therefore exacerbated the challenge of identifying Coleus in Australia. This species also produces cleistogamous flowers, which lend to its remarkably high potential for dispersal.