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Labiatae: Prostanthera marifolia

Unknown Collector, 1976

Species

Prostanthera marifolia R.br

Original Distribution

Australia, New South Wales

Habitat

The sites are located on deeply weathered clay-loam soils associated with ironstone and scattered shale lenses, a soil type which only occurs on ridge tops and has been extensively urbanised

Extinction Data

IUCN = N/a, PRESUMED EXTINCT on the schedules of the NSW Threatened Species Conservation Act., Listed Extinct by WCMC 1996

Description

Prostanthera marifolia R. Br. has recently been characterised by (B Conn in litt.) as an 'erect, openly branched shrub up to c. 0.3 m high; faintly aromatic. Branches subterete, sparsely to moderately hairy [16–20 hairs/mm²]; hairs ± straight, spreading or slightly retrorse, c. 0.3–0.6 mm long, white; sparsely glandular [up to 6 glands/mm²]. Leaves green, faintly aromatic (when crushed), sparsely to moderately hairy [as for branches]; sparsely glandular [as for branches]; petiole 0.5–1 mm long; lamina ovate to almost elliptic, 8–12(-15) mm long, 4–6(-8) mm wide [length to width ratio 1.7–2.2, length of maximum width from base to total lamina length ratio 4–6]; base shortly attenuate; margin entire or occasionally slightly 1-lobed on each side, rarely with one additional lobe, may appear bluntly 1-toothed on each side because margin slightly recurved; apex rounded; venation not visible, except midrib raised on lower surface. Inflorescence a frondose racemiform conflorescence, uniflorescence monadic; 2–8(-12)-flowered [per conflorescence]. Pherophylls absent. Podium 1–1.5(-2.3) mm long, sparsely to moderately hairy [as for branches], sparsely glandular [as for branches]. Prophylls inserted near middle or on distal half of podium [a1 axis to anthopodium ratio 1.2–1.9], opposite, narrowly elliptic to narrowly obovate, 1–1.5 mm long, c. 0.2 mm wide [length to width ratio 5–8, length of maximum width from base to total lamina length ratio 0.6–0.9], with long spreading hairs [as for branches]; base attenuate or truncate to very slightly broader; margin entire; apex obtuse. Calyx light green, with mauve-purple tinge adaxially; outer surface sparsely to moderately hairy [10–18 hairs/mm²], hairs spreading, 0.4–0.8 mm long; sparsely to moderately glandular [10–15 glands/mm²]; tube 1.3–1.8(-2) mm long; abaxial lobe very broadly ovate, 2.5–3.8 mm long, 2.2–3.2 mm wide [length to width ratio 1.1–1.2], apex obtuse to rounded; adaxial lobe very broadly ovate, 2.5–3.6 mm long, 2.5–3 mm wide [length to width ratio 1–1.2] apex obtuse [adaxial lobe length to abaxial lobe length ratio 0.9–1]. Corolla (9-)10–15 mm long, purple, white on inner abaxial surface of tube; outer surface sparsely to moderately hairy [10–30 hairs/mm²], sparsely glandular [10–16 glands/mm²]; inner surface sparsely to moderately hairy (similar to outer surface); tube (5-)6–8 mm long; abaxial median lobes very broadly obovate or spathulate, 8–10(-12) mm long, 6–7(-9) mm wide [length to width ratio 0.9–1.2], apex bilobed (sinus 1.8–3 mm long, 2–3 mm wide distally); lateral lobes obovate to slightly oblong, 6–8(-9) mm long, 4–6 mm wide [length to width ratio 1–1.5], apex slightly undulate, obtuse; adaxial median lobe-pair depressed ovate, 3–4(-4.5) mm long, 6.5–8(-9) mm wide [length to width ratio 0.4–0.5], deeply bilobed (sinus c. 3 mm long), apex of each lobe rounded. Stamens inserted 1.5–2 mm above base of corolla; filaments 3–3.5 mm long, glabrous; anthers 0.8–1 mm long, lobes slightly cristate on basal dorsal surface (trichomes narrowly triangular, c. 0.1 mm long), lobes with basal acumen to 0.1–0.2 mm long, connective extended to form basal appendages 0.6–0.9 mm long, terminating in a few triangular trichomes c. 0.1 mm long. Disc ± cylindrical, 0.2–0.3 mm long. Pistil 6–8 mm long; ovary cylindrical to obovoid, 0.4–0.5 mm long, diameter at base 0.3–0.4 mm, lobes 0.1–0.2 mm long, glabrous; style 6–7 mm long; stigma lobes 0.3–0.4 mm long. Fruiting calyx not to very slightly enlarged (abaxial lobe 3.5–3.8 mm long, c. 3.5 mm wide [length to width ratio 1–1.1]; adaxial lobe 3.5–3.7 mm long, c. 3.5 mm wide [length to width ratio 1–1.1]; [adaxial lobe length to abaxial lobe length ratio c. 1]). Mericarps 1.5–1.8 mm long, distally c. 0.5 mm extended beyond base of style, distal diameter c. 1 mm; seeds slightly obovoid-cylindrical, c. 1 mm long, 0.5–0.7 mm diameter

Number of Specimens at Kew

8

Specimen Type (Y/N)

Y

Kew Herbcat Barcode Number

K000518014

Date Collected

1976?

Other Information

This species was listed as presumed extinct prior to the establishment of the NSW Scientific Committee in 1996. The Scientific Committee is now responsible for maintaining the schedules of the Threatened Species Conservation Act and listing new threatened species.Prostanthera marifolia is threatened by habitat loss due to small-scale clearing. One site is adjacent to a main arterial road, and consequently is vulnerable to road widening and maintenance activities, as well as future housing development. A second site is adjacent to a golfcourse, and may be threatened by maintenance activities. The third and smallest site is protected from clearing within Garigal National Park, but is located very close to the Park boundary near an existing cleared area. 'Clearing of native vegetation' is listed as a Key Threatening Process under the Threatened Species Conservation Act 1995.The population comprises a very low number of individuals (approximately 90-130 when the sites were surveyed in 2005). The one site in Garigal National Park has currently only one known standing plant, although a persistent seed bank may be present in the soil. Most individuals occur in the largest site that contains 76-83% of the total population. The response of P. marifolia to fire is currently not known (B. Conn pers. comm.). Fire history maps show there were major fires in the area in 2000/01 and 1990/91, however due to the fragmented landscape, they may not necessarily have burnt the highly restricted sites where P. marifolia occurs.Prostanthera marifolia plants occur as localised patches in or in close proximity to the Duffys Forest Ecological Community, which is listed as an Endangered Ecological Community in Schedule 1, Part 3 of the Threatened Species Conservation Act 1995. The sites are located on deeply weathered clay-loam soils associated with ironstone and scattered shale lenses, a soil type which only occurs on ridge tops and has been extensively urbanised. As a consequence of habitat fragmentation and edge effects from adjacent urban land uses, all three known sites of Prostanthera marifolia are threatened by habitat degradation processes that are commonly associated with urban interfaces. These include urban stormwater run-off and seepage, fertiliser and herbicide drift, weed invasion, excessive human traffic and rubbish dumping. Arson and infection by soil pathogens may also pose threats, depending on the response of the species

Information Sources

Briggs, J.D. & Leigh, J.H. (1996) Rare or threatened Australian Plants. CSIRO publishing, Melbourne.Walter, K.S. and Gillett, H.J. (eds) (1998). 1997 IUCN Red List of Threatened Plants. Compiled by the World Conservation Monitoring Centre IUCN – The World Conservation Union, Gland, Switzerland and Cambridge, UK