Prostanthera cineolifera R.T.Baker & H.G.Sm., J. Proc. Roy. Soc.

Prostanthera cineolifera R.T.Baker & H.G.Sm., J. Proc. Roy. Soc. View in CoL New South Wales 46(1): 105, t. 1 (1912)

( Fig. 4 View Fig , 5 View Fig , 6 View Fig , 7 View Fig .)

Type citation: ‘ Singleton (Howitz). Siberia , Broke , ( C. H. Cheesebrough [sic]). Cedar Creek, Millfield ( C. F. Laseron) ’. Type: New South Wales. Siberia, Broke, Mar. 1912, C. H. Cheeseborough [sic] s.n. (lecto, here designated: NSW 134514 About NSW ! Residual syn: New South Wales. Singleton , 27 Oct. 1908, Mr Howitz s.n. ( BRI AQ0522596 About BRI *); New South Wales. Cedar Creek , Millfield , s. dat., C. F. Laseron s.n. (no specimen located, n.v.)) .

Shrub, single or multi-stemmed to 1–4(–6) m tall, 1–3 m wide. Branchlets quadrangular, grooved below leaf insertions, covered with scattered glandular trichomes and densely covered with simple non-glandular hairs, each hair usually sinuate (sometimes with a simple curl), mostly ±antrorse, 0.2–0.4 mm long, white. Juvenile leaves (including leaves on water shoots) larger than adult leaves, margins often dentate with up to six small teeth per leaf, one known population retains a few dentate teeth on some mature plants. Leaves mid-green above, paler below; petiole 3–8 mm long; lamina ovate to lanceolate, 14–30 mm long (to 48 mm on juvenile leaves), 5–14 mm wide (to 16 mm on juvenile leaves), length to width ratio 2.5–4.0, length of maximum width from base to total lamina length ratio 0.3–0.6, base attenuate to cuneate, margin entire, apex obtuse, non-glandular hairs absent except for prominent midrib on abaxial surface (there densely distributed, ±antrorse, sinuate, 0.1–0.2 mm long), in depressed midrib on adaxial surface (depressed for ~2/3 length, dense to sparse antrorse non-glandular hairs to 0.25 mm long) and usually proximal third of margin (antrorse simple non-glandular hairs up to 0.25 mm long); abaxial surface moderately to densely glandular (15–60 mm −2), secondary veins often visible; adaxial surface densely glandular (25–70 mm −2), secondary veins indistinct. Inflorescences: thryses to ~ 13 cm long with dichasia usually reduced to single flowers. Floral bracts early caducous, narrowly naviculate, ~ 2.5 mm long, ~ 0.75 mm wide; apex obtuse; abaxially sparsely to densely glandular; adaxially non-glandular hairs mostly absent but margin ciliate with non-glandular hairs to 0.15 mm long. Pedicel 1.25–4.75 mm long, moderately covered with non-glandular hairs, antrorse, ~ 0.1 mm long, glandular trichomes moderately common. Floral prophylls caducous, a 1 axis to anthopodium ratio 1.0–3.0, opposite or subopposite, narrowly naviculate, 2.2–3.0 mm long, ~ 0.1 mm wide, margin entire with curled non-glandular hairs to 0.25 mm long; abaxial surface with scattered to dense glands; glandular trichomes rare on adaxial surface; venation not visible in fresh specimens. Calyx green to maroon, bilobed, both lobes adpressed to the corolla; outer surface with a moderate to dense cover of glandular trichomes, with scattered non-glandular hairs becoming ±glabrescent with age, non-glandular hairs sometimes remaining on abaxial half of calyx tube only; inner surface without non-glandular hairs but non-glandular hairs densely distributed towards margin of lobes, up to 0.2 mm long; margin densely ciliate, with many white non-glandular hairs up to 0.25 mm long; tube 2.0– 2.5 mm long, sometimes ridged, particularly in dried specimens; abaxial lobe elliptic, 1.0–2.0 mm long, 1.5–3.0(–4.0) mm wide at base; apex usually rounded; adaxial lobe transversely elliptical, 0.5–1.0(–1.7) mm long, 2.5–4.0(–6.0) mm wide at base; apex usually rounded, adaxial lobe length to abaxial lobe length ratio 0.3–0.8. Corolla pink–mauve; adaxial corolla tube length 3.5–6 mm long; outer surface moderately hairy distally (antrorse non-glandular hairs up to 0.2 mm long); margin usually without non-glandular hairs, sometimes scattered minute non-glandular hairs, glandular trichomes occasional; inner surface of tube and lobes with non-glandular hairs or with scattered very short antrorse non-glandular hairs to 0.1 mm, glandular trichomes occasional; abaxial median lobe broadly elliptic to circular, 1.5–4 mm long, 1.3–3.5 mm wide, 0.8–3.25 mm wide below distal lobing, length to width ratio 0.9–1.3; apex rounded; margin slightly irregular and slightly undulate, occasionally a shallow sinus up to 0.25 mm deep; lateral lobes very broadly ovate to ovate, 1.5–2.75 mm long, 1.0– 3.25 mm wide, length to width ratio 0.9–1.5; apex rounded; margin regular; adaxial median lobe-pair broadly depressed ovate, 0.9–2.5 mm long, 1–2.5 mm wide, length to width ratio 0.8–1.1; margin regular. Stamens inserted 0.7–1.6 mm above corolla base; abaxial stamens with filament 1.2–2.4 mm long; adaxial stamens with filament 1.2–2.0 mm long; anthers cream to pink, locules 0.6–0.9 mm long; connective extended to form 1 or 2 basal appendages (one appendage usually shorter than the other), extending beyond base of anther and terminating with 12–~50 translucent conical hairs; length beyond the anther of appendage including hairs up to ~ 0.25 mm; hairs to 0.1 mm. Pistil 4–7 mm long; ovary cylindrical obovoid, 1.1–1.3 mm long, diameter at base 0.7–0.9 mm, lobes 0.5–0.6 mm long; style 3.25–5.75 mm long; stigmatic lobes 0.4–0.5 mm long. Fruiting calyx only slightly enlarged, adaxial lobe surrounds the folded-over abaxial lobe that conceals developing mericarps. Mericarps maturing to offwhite or cream to charcoal (often mottled), 1.4–1.8 mm long, wrinkled and minutely papillose, distally 0.6–0.9 mm extended beyond base of style.

Phytochemistry

The main essential oils in P. cineolifera are 1,8-cineole, prostantherol and p-cymene. Bicyclogermacrene, caryophyllene oxide and α-pinene are essential oils found in P. cineolifera but not in P. ovalifolia sens. lat. (from Mount Stanley), P. dyarubbin sp. nov. or P. milleri sp. nov. (tables 2, 4 in Sadgrove et al. 2020; Supplementary Table S 4). Aromatic with a scent of 1,8-cineole when crushed.

Distribution

Extant populations of P. cineolifera occur in the Hunter, Kerrabee and Yengo subregions of the Sydney Basin bioregion on the western and southern sides of the Hunter Valley from Wingen Maid north-west of Scone south-east to Bellbird and as far west as Goulburn River National Park. There are historical specimens in New South Wales from Manilla and Upper Moore Creek in the Nandewar bioregion ( Fig. 6 View Fig ).

Habitat

The species grows in skeletal sandy soil at altitudes of up to 630 m on sandstones and conglomerates of the Narrabeen Group ( Colquhoun et al. 2022), often associated with ridges, cliff lines and extending down gullies. At the western limit of the range, P. cineolifera is confined to gully bottoms. The vegetation consists of eucalypt open forest or woodland with dominant species Angophora costata , Eucalyptus deanei , E. fibrosa , E. punctata or E. sparsifolia .

Phenology

Flowers late September to early November; fruiting from mid-November.

Conservation status

Our extensive fieldwork (J. J. Bruhl, I. R. H. Telford, R. L. Andrew and especially R. L. Palsson) has primarily indicated that of the populations known to us, P. cineolifera is currently protected in Pokolbin State Forest (Bees Nest Ridge and Yellow Rock Road, and parts of Sawpit Road and Broken Back Trail), Singleton Military Area, Wingen Maid Nature Reserve, Wollemi National Park (Cousins Creek), Goulburn River National Park and in the 635-ha Cedar Creek biodiversity offset, now Cedar Creek Nature Reserve (S. A. J. Bell, unpubl. data, 2017).

Only the small population at Wallaby Rocks appears to be threatened. In 2011, Driscoll collected P. cineolifera (NSW 891464) from ‘top of Wallaby Rocks’. Our two searches have not yielded any plants on top of Wallaby Rocks. Currently, the population is confined to south-western cliff-lines; ‘pushed’ to cliff lines possibly by fire or grazing pressure. Grazing pressure is likely an important factor, as several heavily browsed plants were found on lower parts of cliff-lines. This possibly threatened population is genetically similar to the larger protected Wingen Maid population ( Palsson et al. 2024, fig. 3b) that unfortunately does have the lowest genetic diversity of the P. cineolifera populations ( Palsson et al. 2024, table 4). We recommend that effort be applied to feral goat control at Wallaby Rocks to protect this small, threatened population.

Frequent fire is a potential threat to P. cineolifera , as this species is considered fire sensitive ( Department of the Environment 2008). The largest known populations are in the Pokolbin area on Bees Nest Ridge and Yellow Rock Road, an area that was severely affected by the 2019–20 fires. Fortunately, most populations occurred in areas in which the canopy was unburnt. Six months post fire, there was evidence of large burnt stands of P. cineolifera , some resprouting from trunks and seedling recruitment (Luke Foster, Department of Planning, Industry and Environment, pers. comm., 2021).

Prostanthera cineolifera is currently listed as Vulnerable under both Commonwealth and NSW legislation (Office of Environment and Heritage 2019). As of 2018, the number of individuals was <10,000 with Extent of Occurrence (EOO) of 14,000 km 2 and Area of Occupancy (AOO) of 44 km 2 (R. L. Palsson, R. L. Andrew, I. R. H. Telford and J. J. Bruhl, unpubl. data). Since 2018, several more populations of>1000 individuals and two more locations have been discovered along with recruitment observed by Foster. Also, the Broken Back Range populations were burnt in the summer of 2019 –20 and 18 months later mass recruitment was observed by R. L. Palsson et al. The status of Vulnerable may still be met for P. cineolifera but discovery of yet more populations in little surveyed areas such as Wollemi National Park would likely enable the status of ‘Least Concern’ (International Union for Conservation of Nature 2019) to be met for this species.

Notes

Three geographically separate gatherings are cited in the protologue ( Baker and Smith 1912). Only two specimens of these three syntypes could be located; i.e. C.H. Cheeseborough [sic] s.n. (NSW 134514) and Mr Howitz s.n. (BRI AQ0522596). The NSW specimen was selected as the lectotype as this is a fruiting specimen that was seen by R. T. Baker. The sheet bears the original ‘Technological Museum, Sydney’ label with R. T. Baker’s name ( Fig. 7 View Fig ). By comparison, the syntype of P. cineolifera collected by Howitz is a sterile specimen that does have a ‘Technological Museum, Sydney’ label but does not bear Baker’s name, [handwriting] and therefore we treat the Howitz sheet as a residual syntype. There is a specimen of P. cineolifera at the Queensland Herbarium (BRI AQ0336458) that was collected by C.H. Cheesebrough [sic] from the type location that bears two separate annotations in addition to the original label from the Technological Museum, Sydney. One, in red printing has ‘PART OF TYPE COLLECTION’ and the other a Queensland Herbarium specimen note ‘ syntype Prostanthera cineolifera R.T.Baker & H.B.Sm. J. Proc. Roy. Soc. NSW View in CoL 46(1): 105 (1912).’ However, the date of collection on the original label is ‘ June 1915 ’, 3 years after the publication of the species. Therefore, we consider this material a topotype of no nomenclatural status and not part of the original material for this name.

The spelling of the collector of the specimens from Siberia, Broke, is problematic. Both ‘Cheesebrough’ and ‘Cheeseborough’ are given on specimen labels and the specimen citation in Baker and Smith (1912). Neither of these spellings appears to have been recorded as a family name in Australia. By contrast, the first mention of the collector’s name in Baker and Smith (1912, p. 104) was ‘In March of this year a quantity of this plant was forwarded to the Museum, by Mr C. H. Cheesbrough of Siberia, Broke, near

Singleton...’. So, ‘Cheesbrough’ appears to be the correct spelling for the collector.

Prostanthera cineolifera is distinguished from other species of Prostanthera in the Hunter and Hawkesbury River catchments by a loose open inflorescence, a stem indumentum of sinuate ± antrorse non-glandular hairs and both calyx lobes are firmly adpressed to the corolla in both the developing bud and fully expanded flower.

Prostanthera cineolifera has been confused with P. dyarubbin , P. milleri , P. lanceolata and P. ovalifolia . Prostanthera cineolifera can be distinguished from P. lanceolata and P. ovalifolia by the calyx lobes of the latter two species being ±perpendicular to the corolla in both the developing bud and fully expanded corolla. Prostanthera cineolifera can be distinguished from P. dyarubbin and P. milleri that both have more compact inflorescences, persistent hairy floral prophylls and reflexed calyx lobes. In both P. dyarubbin and P. milleri , the ±shield-shaped floral bracts are more often observed, whereas in P. cineolifera , the lanceolate and naviculate floral bracts are only observed on early buds. Vegetative material of P. cineolifera has been confused with P. discolor ; both species have similar stem indumenta but the entire leaf margins of P. discolor are ornamented with minute teeth (visible using a hand lens), whereas the proximal third of the leaf margins of P. cineolifera usually have antrorse non-glandular hairs.

Selected specimens examined

NEW SOUTH WALES: North Western Slopes: Manilla , Oct. 1912, B. J . Moss s.n., ( NSW 232116 About NSW !); Upper Moore Creek, Tamworth , 1933, E . Wyndham s.n. ( NSW 134411 About NSW !); Central Western Slopes: Scone , 31 Aug. 1907, R. H . Cambage s.n. ( NSW 227969 About NSW !); Wingen Maid Nature Reserve, north of Salisbury Trig , 09 Oct. 1997, J. R . Hosking 1498 ( CANB, MEL, NE!, NSW); Goulburn River National Park, Morrisons Flat Trail , 11 Oct. 2022, R. L . Palsson 539, J. L . Griffiths , P . Bussell & E . Gill ( NE!, NSW!); Wallaby Rocks, Wybong, 8 Sep. 2012, N. J . Sadgrove 291 ( CANB, MEL, NE!, NSW); Above Cousins Creek, NW Wollemi National Park , 22 Aug. 1988, S. A. J . Bell s.n. ( NSW 424206 About NSW !). North Coast: Bellbird , Limestone Creek , 7 Oct. 2016, L. M. C . Foster s.n. ( NE 106633 !); Pokolbin State Forest, Bees Nest Ridge Rd , 10 Oct. 2017, R. L . Palsson 155, R. L . Andrew , J. J . Bruhl & I. R . Telford ( NE!); Pokolbin State Forest, Broken Back Trail , 5 Oct. 2017, R. L . Palsson 134 & M. R . Donald, ( NE!); Pokolbin State Forest, Yellow Rock Road , 26 Oct. 2021, R. L . Palsson 483, L. M. C . Foster , E . Gill, ( NE!, NSW!); Pokolbin State Forest, Sawpit Rd , 1.8 km from junction with Cedar Creek Rd, 6 Oct. 2017, R. L . Palsson 139 & M. R . Donald ( NE!, NSW!) .