NSW Scientific Committee - final determination
The Scientific Committee has found that:
1. Senecio linearifolius var. dangarensis Belcher ex I.Thomps. is an endemic Australian shrub. The species, Senecio linearifolius A.Rich., includes eight varieties and occurs in south-eastern Australia. Thompson (2004) described the species as "Aromatic perennials, often weakly shrubby, to 2 m high, glabrous or nearly so except on lower surface of leaves, sometimes glaucous. Stems becoming many-stemmed from base, branching mostly in upper half. Leaves commonly + thin to coriaceous, rarely somewhat fleshy; leaves in middle to upper third of stems narrow to very narrow-elliptic, narrow--ovate, lanceolate, or linear, 2-20 cm long, 1-40 mm wide, with l:w ratio c. 1.5-30, undivided; base attenuate, truncate, cordate, or variously auriculate, with auricles divided or not, slightly amplexicaul or not; margin entire, denticulate, dentate or serrate; upper surface glabrous, occasionally sparsely appressed-cobwebby, glabrescent, sometimes sparsely and minutely hispid; lower surface glabrous, or variously cobwebby to woolly, with hairs all fine and + appressed or sometimes spreading; secondary and tertiary venation variably distinct. Unit inflorescences of several to many capitula; peduncles finally to c. 15 mm long. Capitula: calycular bracteoles 2-6, 1.5-3.0 mm long; peduncle and margin of bracteole glabrous or cobwebby at anthesis, sometimes glaucous; involucre cylindric to weakly campanulate, 2.5-5.5 mm long, 1.5-3.0 mm diam.; phyllaries 7-12(-14); stereome slightly to moderately convex, usually glabrous. Florets 12-30; ligulate florets 4-8, ligules 3-8 mm long, with nerves commonly 4; disc florets 4.0-5.5 mm long; limb mostly slightly longer than tube. Achenes narrow-obloid or narrow oblong-ellipsoid, 1.3-2.5 mm long, brown, glabrous or with papillose hairs in bands, hairs with a l:w ratio of 2-3; carpopodium small, slightly exserted. Pappus 4-6 mm long."
Senecio linearifolius var. dangarensis Belcher ex I.Thomps. is distinguished from the other varieties of the species by Thompson (2004) as follows:
"Plants glaucous, in parts strongly so, on stems, lower surface of leaves, peduncles and capitula ± glabrous. Upper-stem leaves narrow to very narrow-elliptic, with l:w ratio 5-8; base cuneate to broad-cuneate; auricles absent; margin denticulate; lower surface glabrous; secondary venation ± distinct; tertiary venation distinct. Inflorescences: peduncles glabrous, or rarely cobwebby, at anthesis. Capitula: involucre 3.5-5.0 mm long 2.0-2.8 mm diam.; phyllaries mostly c. 12. Florets 20-31; ligulate florets mostly 7-9; disc florets 13-22. Achenes c. 2.0 mm long, with appressed papillose hairs in bands."
Senecio linearifolius var. dangarensis has previously been known as Senecio sp. C sensu Harden (1992), and Senecio 'dangarensis' (a manuscript name that was never published, Thompson pers. comm.).
2. Senecio linearifolius var. dangarensis is restricted to a single known population in the Goulburn River National Park where it has been recorded growing on an open scree slope (Thompson 2004) and in woodland and rainforest communities on basalt (Hill 1999). Vegetation surveys in the Wollemi (Bell 1998) and Towarri National Parks (Hill et al. 2002); the Munghorn Gap (Hill 1999), Manoblai (T. Peake and S. Bell unpublished data), Cedar Brush and Wingen Maid Nature Reserves (Hill et al. 2002); and on Crown (Bell 1997, Fallding et al. 1997, T. Peake and S. Bell unpublished data) and private land (T. Peake unpublished data) in the Hunter Valley have failed to locate any additional populations of the species.
3. The population is estimated to contain 500 - 1000 individuals over an area of c. 20 hectares (T. Peake pers. comm., 2003).
4. Senecio linearifolius var. dangarensis is threatened by environmental and demographic stochasticity due to the low number of mature individuals and very highly restricted distribution. High abundances of weeds, in particular Cirsium vulgare and Carduus pycnocephalus, may also be threatening seedling recruitment (T. Peake pers. comm., 2003).
5. In view of the above, the Scientific Committee is of the opinion that Senecio linearifolius var. dangarensis Belcher ex I.Thomps. is likely to become extinct in nature in NSW unless the circumstances and factors threatening its survival or evolutionary development cease to operate.
Dr Lesley Hughes
Chairperson
Scientific Committee
Proposed Gazettal date: 21/10/05
Exhibition period 21/10/05 - 16/12/05
References
Bell SAJ (1997) 'Vegetation survey and mapping of Crown land, south of Manobalai Nature Reserve, Upper Hunter Valley.' Report to the Department of Land and Water Conservation and the NSW National Parks and Wildlife Service, Upper Hunter District.
Bell SAJ (1998) 'Wollemi National Park vegetation survey. A fire management document.' Report to the NSW National Parks and Wildlife Service, Upper Hunter District.
Fallding M, Bell S, Murray M (1997) 'Myambat vegetation and fauna management. Guidelines for Landscape Management at the Myambat Logistics Company Site.' Report by Land and Environment Planning to the Department of Defence.
Harden GJ (1992) Flora of New South Wales. Volume 3. (University of NSW Press, Kensington.)
Hill L (1999) 'Goulburn River National Park and Munghorn Gap Nature Reserve vegetation survey for fire management purposes.' Report to the NSW National Parks and Wildlife Service, Upper Hunter District.
Hill L, Peake T, Bell S, Raine A (2002) 'Vegetation survey and mapping of Towarri National Park, Cedar Brush Nature Reserve and Wingen Maid Nature Reserve.' Report to the NSW National Parks and Wildlife Service, Upper Hunter District.
Thompson IR (2004) Taxonomic studies in Australian Senecio (Senecioneae - Asteraceae). II. The shrubby discoid species and the allied radiate species Senecio linearifolius. Muelleria 20, 67-110.