Grevillea ilicifolia (R.Br.) R.Br. subsp. ilicifolia - critically endangered species listing

NSW Scientific Committee - final determination

The Scientific Committee, established by the Threatened Species Conservation Act, has made a Final Determination to list the shrub Grevillea ilicifolia (R.Br.) R.Br. subsp. ilicifolia as a CRITICALLY ENDANGERED SPECIES in Part 1 of Schedule 1A of the Act. Listing of Critically Endangered species is provided for by Part 2 of the Act.

 

The Scientific Committee has found that:

 

1. Grevillea ilicifolia (R.Br.) R.Br. subsp. ilicifolia (Holly-leaf Grevillea) (family Proteaceae) is a small to medium spreading to erect shrub 0.2—2 m tall, sometimes with multiple stems from ground level, with cuneate to roughly kite-shaped leaves 2-7 cm long and 0.8-3.5 cm wide, with a basal section cuneate and apical half usually shallowly to moderately divided into 3-5 triangular to ovate simple lobes (occasionally some leaves simple and elliptical); leaf upper surface usually grey-green to bluish green, sometimes inconspicuously hairy; lower surface densely covered with appressed straight hairs. The flowers are borne in short secund (one-sided) heads 2-5 cm long; individual flowers zygomorphic, with a pale green to grey perianth, the perianth with appressed silky hairs on the outer surface and hairless inside; the pistil is 19-25 mm long, red or rarely pink, orange or pale yellow, with a hairy stipitate ovary near the base, hairless above. The fruit is an ovoid follicle 10-16 mm long, the surface hairs patterned to form reddish or purplish streaks. Full descriptions and illustrations are available in McGillivray & Makinson (1993) and Makinson (2000a), as ‘G. ilicifolia leaf variants b, c, f’; and in Olde & Marriott (1995) as ‘G. ilicifolia var. ilicifolia wedge-leaved form’. Briefer descriptions are available in Makinson (2000b, 2002 – only the left-hand leaf illustrated in each case) and in Dowling et al. (2004).

 

2. Grevillea ilicifolia subsp. ilicifolia is one member of a complex of related taxa, formerly grouped variously (McGillivray & Makinson 1993, Olde and Marriott 1995, Makinson 2000a,b) as forms, races or varieties of a broadly defined Grevillea ilicifolia. Taxonomic work by Dowling et al. (2004) resulted in the recognition of several taxa at species and subspecies rank; following that work the only member of the complex known to occur in New South Wales is G. ilicifolia subsp. ilicifolia.

 

3. In New South Wales, Grevillea ilicifolia subsp. ilicifolia occurs, or has occurred, at highly disjunct localities in the central west and central south of the State. The only population confirmed as extant occurs at Round Hill Nature Reserve north-west of Lake Cargelligo. Until recently the taxon also occurred in the Griffith area where the last known plant of that population, at Nericon, died in 2008 (D. Egan in litt. Dec. 2009). The Griffith-area population is now likely to be extinct, but the few early records of it (NSW Herbarium records from 1955 onward) have imprecise localities; persistence of some plants at other sites in the area cannot be ruled out. A single unvouchered observational report exists of Grevillea ilicifolia having occurred also in the West Wyalong area as late as the early 1970s (W. Molyneux pers. comms 1994, April 2010), and the NSW Wildlife Atlas contains one plant-list record (1728-03FL) from Woggoon Nature Reserve near Condobolin. Subsequent untargeted surveys of the West Wyalong mallees and of Woggoon NR have not substantiated occurrence in either area. Grevillea ilicifolia subsp. ilicifolia has a very highly restricted geographic distribution in NSW. Both the area of occupancy and extent of occurrence of the known extant population are estimated to be 4km2 based on occupancy of a single 2 x 2 km grid cell, the scale recommended for assessing area of occupancy by IUCN (2010). Grevillea ilicifolia subsp. ilicifolia is not endemic to New South Wales, occurring also in western Victoria and south-eastern South Australia.

 

4. In New South Wales Grevillea ilicifolia subsp. ilicifolia has been recorded from shrubby mallee communities. At Nericon near Griffith, Weare (1988) reports it as having occurred in ‘dense mallee’ in the early 1950s; the sole known plant of this population surviving in recent decades was growing in sandy loam soil in a disturbed remnant association of mallee eucalypts (Eucalyptus gracilis, E. socialis and E. dumosa), with Callitris glaucophylla, Acacia brachybotrya and Olearia pimeleoides (NSW Herbarium specimen data, Makinson 1307, 1993). At Round Hill Nature Reserve near Lake Cargelligo, it occurs in red sandy soil in a mallee association of Eucalyptus socialis, E. leptophylla, and Callitris verrucosa, with a shrubby understorey of Acacia montana, Dodonaea viscosa subsp. cuneata, Triodia sp., Prostanthera serpyllifolia, Santalum sp., Myoporum sp., and Phebalium squamulosum (Australian National Herbarium Specimen Information Register, 2010). The reported West Wyalong occurrence was a single plant in a roadside mallee remnant. Grevillea ilicifolia subsp. ilicifolia in other States is recorded from habitats of mallee, heath, and woodland on a variety of soil types.

 

5. In New South Wales, Grevillea ilicifolia subsp. ilicifolia is known to occur in one conservation reserve (Round Hill Nature Reserve near Lake Cargelligo), where searches over a number of years have located plants recorded as numbering four (R. Makinson 1994, herbarium vouchers CANB 9407339, 9407 340, 9407341), five (N. Taws in litt. 1994), or three (Whiting 1998), with an anonymous report of 12 at this location cited in Dowling et al. (2004). The possibly extinct population in the Griffith area is not known to have occurred at any sites now contained within conservation reserves; this population was known in recent decades only from a single plant.

 

6. Grevillea ilicifolia subsp. ilicifolia in New South Wales probably flowers from September to November. It is likely to be primarily bird-pollinated, although introduced Honeybees (Apis mellifera) may be able to effect pollination. The taxon is thought to be an obligate out-breeder (R. Makinson in litt. 2010; N. Marriott in litt. 2010). It is also likely to reproduce only from seed; it is not known to be capable of producing rhizomatous ramets (‘root-suckers’), although there is one record of a single cultivated plant of the closely related G. ilicifolia subsp. lobata (F. Muell.) T.L. Downing producing rhizomatous ramets after wildfire (Marriott 2007; N. Marriott in litt. March 2010), and McGillivray & Makinson (1993) refer to the species complex, broadly defined, as ‘sometimes root-suckering’. Grevillea ilicifolia subsp. ilicifolia is however capable of resprouting, after fire or other damage, from the base of the stem or crown of the rootstock, although observations of Victorian populations (N. Marriott in litt. March 2010) suggest significant variation in the frequency and degree of resprouting vigour. Longevity of plants and soil-stored seed is unknown, but plants are likely to be able to live for up to several decades (D. Egan in litt. 2009).

 

7. Decline in distribution and numbers of Grevillea ilicifolia subsp. ilicifolia in New South Wales is inferred to have been severe, although in this State the taxon is likely to have been rare and with a naturally highly fragmented distribution even prior to European settlement. A major decline in potential habitat occurred as a direct result of the extensive clearing of mallee communities, particularly in the central and south-central parts of the State, from about 1890 to 1950, and the progressive loss of small remnant patches since. It is likely that any populations of Grevillea ilicifolia subsp. ilicifolia in remnant patches have declined rapidly in recent decades as a result of increasing senescence coupled with low reproductive rates. The apparent reproductive self-incompatibility of this taxon would be a strong driver of decline once population densities (and perhaps bird pollinator visitation rates) drop below a certain level.

 

8. Threats to Grevillea ilicifolia subsp. ilicifolia include land-clearing (probably the primary cause of decline of the taxon in the Griffith area). Potential threats, possibly operative at both the Griffith and Round Hill sites, also include inappropriate fire frequencies, and grazing and browsing by herbivores. The susceptibility of the species to pathogens such as the introduced Phytophthora cinnamomi (the causal agent of die-back root-rot) is unknown, but many Grevillea species are known to be susceptible (Environment Australia 2001; McDougall 2006; Cahill et al. 2008). Phytophthora is spread by movement of water and soil, and the few known extant plants at Round Hill Nature Reserve are within 3-60 m of a dirt road. The semi-arid environment is however marginal for Phytophthora. Road maintenance activities and vehicle traffic off-road are also potential threats to this population. ‘Clearing of native vegetation’, 'High frequency fire resulting in the disruption of life cycle processes in plants and animals and loss of vegetation structure and composition', ‘Competition and grazing by the feral European Rabbit Oryctolagus cuniculus (L.)’, ‘Competition and habitat degradation by Feral Goats, Capra hircus Linnaeus 1758’, and ‘Infection of native plants by Phytophthora cinnamomi are listed as Key Threatening Processes under the NSW Threatened Species Conservation Act 1995.

 

9. Grevillea ilicifolia (R.Br.) R.Br. subsp. ilicifolia is eligible to be listed as a Critically Endangered species as, in the opinion of the Scientific Committee, it is facing an extremely high risk of extinction in New South Wales in the immediate future as determined in accordance with the following criteria as prescribed by the Threatened Species Conservation Regulation 2010:

 

Clause 7 Restricted geographic distribution and other conditions

The geographic distribution of the species is estimated or inferred to be:

(a) very highly restricted,

and either:

(d) a projected or continuing decline is observed, estimated or inferred in either of the key indicators:

(a) an index of abundance appropriate to the taxon, or

(b) the geographic distribution, habitat quality or diversity, or genetic diversity; or

(e) the following conditions apply:

(i) the population or habitat is observed or inferred to be severely fragmented;

(ii) all or nearly all mature individuals are observed or inferred to occur within a small number of populations or locations.

 

Clause 8 Low numbers of mature individuals of species and other conditions

The estimated total number of mature individuals of the species is:

(a) very low,

and either:

(d) a projected or continuing decline is observed, estimated or inferred in either of the key indicators:

(a) an index of abundance appropriate to the taxon, or

(b) the geographic distribution, habitat quality or diversity, or genetic diversity; or

(e) the following conditions apply:

(i) the population or habitat is observed or inferred to be severely fragmented;

(ii) all or nearly all mature individuals are observed or inferred to occur within a small number of populations or locations.

 

Clause 9 Low number of mature individuals of species

The total number of mature individuals of the species is observed, estimated or inferred to be:

(a) extremely low.

 

 

Dr Richard Major

Chairperson

Scientific Committee

 

Proposed Gazettal date: 17/12/10

Exhibition period: 17/12/10 – 11/02/11

 

References:

 

Cahill DM, Rookes JE, Wilson BA, Gibson L, McDougall KL (2008) Turner Review No. 17. Phytophthora cinnamomi and Australia’s biodiversity: impacts, predictions and progress towards control. Australian Journal of Botany 56, 279–310

 

Dowling TL, Duretto MF, Ladiges PY (2004) Morphological analysis of the Grevillea ilicifolia complex (Proteaceae) and recognition of taxa. Australian Systematic Botany 17, 327-341

 

Environment Australia (2001) Threat Abatement Plan for dieback caused by the root-rot fungus Phytophthora cinnamomi. Environment Australia, Canberra. (available at http://www.environment.gov.au/biodiversity/threatened/publications/tap/phytophthora.html, accessed 12 April 2010)

 

IUCN (2010) ‘Guidelines for using the IUCN Red List Categories and Criteria. Version 8.0.’ (Standards and Petitions Working Group of the IUCN Species Survival Commission Biodiversity Assessments Sub-committee: Switzerland).

(http://intranet.iucn.org/webfiles/doc/SSC/RedList/RedListGuidelines.pdf).

 

Makinson RO (2000a) Proteaceae 2 - Grevillea. Flora of Australia Vol. 17A. (ABRS Canberra/CSIRO Melbourne)

 

Makinson RO (2000b) Grevillea. In ‘Proteaceae of New South Wales’ (Ed. GJ Harden, DW Hardin and DC Godden) pp. 117-151 (University of New South Wales Press, Sydney)

 

Makinson RO (2002) Grevillea. In ‘Flora of New South Wales. Vol. 2 (revised edition)’ (Ed. GJ Harden) pp. 32-66. (University of New South Wales Press, Kensington NSW)

 

Marriott N (2007) The response of Grevillea species to wildfire. Grevillea Study Group Newsletter No 76, Association of Societies for Growing Australian Plants.

 

McDougall K (2006) Appendix 4. The responses of native Australian plant species to Phytophthora cinnamomi. In O’Gara E, Howard K, Wilson B and Hardy GEStJ (2005) Management of Phytophthora cinnamomi for Biodiversity Conservation in Australia. A report funded by the Commonwealth Government Department of the Environment and Heritage by the Centre for Phytophthora Science and Management, Murdoch University, Western Australia.

 

McGillivray DJ, Makinson RO (1993) Grevillea, Proteaceae: a taxonomic revision. (Melbourne University Press Carlton, Vic.)

 

Olde P, Marriott N (1995) The Grevillea book. Vol. 2. (Kangaroo Press, Kenthurst NSW)

 

Weare P (1988) ‘Australian wildflowers.’ Collins: Sydney.

 

Whiting E (1998) Survey of rare and endangered plants within Nombinnie and Round Hill Nature Reserves – May 1998. Unpublished report for Griffith regional office of the NSW National Parks and Wildlife Service.

 

Page last updated: 28 February 2011