Spreading Grevillia (Grevillea humifusa) Interim Recovery Plan 2003-2008

Gillian Stack and Val English
Department of Conservation and Land Management, WA, 2003

4. Term of plan

This Interim Recovery Plan will operate from May 2003 to April 2008 but will remain in force until withdrawn or replaced. If the taxon is still ranked Critically Endangered after five years, the need to review this IRP or to replace it with a full Recovery Plan will be determined.

5. Acknowledgements

The following people have provided assistance and advice in the preparation of this Interim Recovery Plan:

Gina Broun    Conservation Officer, the Department's Moora District
Rebecca Carter    Program Leader Nature Conservation, the Department's Moora District
Anne Cochrane    Manager, the Department's Threatened Flora Seed Centre
Anne Harris    Consultant, the Department's W.A. Threatened Species and Communities Unit
Amanda Shade    Horticulturalist, Botanic Garden and Parks Authority

Thanks also to the staff of the W.A. Herbarium for providing access to Herbarium databases and specimen information, and the Department's Wildlife Branch for assistance.

6. References

Brown, A., Thomson-Dans, C. and Marchant, N. (Eds). (1998) Western Australia's Threatened Flora. Department of Conservation and Land Management, Western Australia.

Department of Conservation and Land Management (1992) Policy Statement No. 44 Wildlife Management Programs. Perth, Western Australia.

Department of Conservation and Land Management (1994) Policy Statement No. 50 Setting Priorities for the Conservation of Western Australia's Threatened Flora and Fauna. Perth, Western Australia.

Department of Conservation and Land Management (1995) Policy Statement No. 29 Translocation of Threatened Flora and Fauna. Perth, Western Australia.

Department of Conservation and Land Management (1998) Western Australian Herbarium FloraBase - Information on the Western Australian Flora. Perth, Western Australia. http://www.calm.wa.gov.au/science/

Fox, J., Dixon, B. and Monk, D. (1987). Germination in Other Plant Families*. Pp. 83-97 in P.L. Langkamp (ed.). Germination of Australian Native Plant Seed. Inkata Press, Melbourne.

Olde, P.M. and Marriott, N.R. (1995). The Grevillea Book 2: 203-204. Kangaroo Press, Kenthurst N.S.W.

Stack, G. and English, V. (1999) Interim Recovery Plan number 25, 1999-2002 Grevillea humifusa. Department of Conservation and Land Management, Perth.

World Conservation Union (2000) IUCN red list categories prepared by the IUCN Species Survival Commission, as approved by the 51st meeting of the IUCN Council. Gland, Switzerland.

7. Taxonomic Description

Olde, P.M. and Marriott, N.R. (1995). The Grevillea Book 2: 203-204. Kangaroo Press, Kenthurst N.S.W.

Grevillea humifusa
Specific epithet from the Latin humifusus (spread along the ground), in reference to the habit.

Lignotuberous shrub with trailing stems to 3 m long. Branchlets angular, openly villous, the hairs to 2.5 mm long. Leaves 1.5-2 cm long, ascending to spreading, shortly petiolate, bipinnatisect; rachis straight to strongly recurved; lobes 0.5-1 cm long, 0.5 mm wide, narrowly linear, ascending to spreading; upper surface pilose, midvein evident to obscure; margins loosely revolute; lower surface partially exposed, pilose, midvein protuberant. Conflorescence 2 cm long, erect or decurved, pedunculate, terminal, simple, conico-secund, dense; peduncle and rachis pilose; bracts 1.5 mm long, ovate, acuminate, villous outside, falling before anthesis. Flower colour: perianth pink to pale red with cream limb; style pink, red or orange-red with yellow tip. Flowers acroscopic; pedicels 3-5 mm long, glabrous; torus c. 1 mm across, oblique; nectary cushion-like, prominent; perianth 5-7 mm long, 1.8-2 mm wide, ovoid, dilated at base, glabrous outside, pubescent inside near curve and along tepal margins, cohering except along dorsal suture; limb revolute, spheroidal-subglobose, silky, not ribbed; pistil 22-24 mm long, glabrous; stipe 3.5 mm long, flattened, incurved; ovary triangular; style before anthesis exserted at curve and looped upwards, afterwards gently incurved; style end slightly expanded, exposed before anthesis; pollen presenter 1-1.2 mm long, oblique, convex, ellipsoidal to orbicular. Fruit 12-15 mm long, 3-4 mm long, erect, oblong, acuminate, with strong basal ridging, grooved; pericarp 0.5 mm thick. Seed not examined.

Distribution W.A., in a small area inland from Jurien. Climate Summer hot, dry; winter cold, wet. Rainfall c. 500 mm.

Ecology Grows in brown, gravelly loam in or near woodland. Flowers autumn-spring. Regenerates from seed or lignotuber. Presumably pollinated by birds.

Major distinguishing features Prostrate habit; branchlets angular, pilose with long white hairs; leaves bipinnatisect, pilose; conflorescence conico-secund; bracts > 1 mm long; perianth zygomorphic, glabrous outside except limb, hairy inside; pistil glabrous; ovary triangular on incurved, flattened stipe; pollen presenter oblique; fruit with strong basal ridging.

Related or confusing species Group 14, especially G. delta and G. preissii, neither of which has a prostrate trailing habit. G. delta also differs in its more hairy perianth and pedicels and in its less crowded flowers. G. preissii also differs in its glabrous to sparsely silky or densely tomentose-villous branchlets.

Variation A morphologically uniform species.

Conservation status 2E. Extremely rare, known from one population of c. 50 plants, beside a road in mostly cleared country.

Cultivation G. humifusa has been cultivated and appreciated widely since the 1960s (as G. thelemanniana Grey-leaf prostrate form). It appears to have been introduced by H. Demarz, collector for Kings Park, Perth, until recently the only collector of the species. It has proved easy to grow in drier, inland as well as coastal climates but is sometimes short-lived in summer rainfall areas. It endures frost to at least -3ºC and extended dry conditions without damage. It grows best in well-drained but moist acidic to slightly alkaline sand, sandy loam or gravelly loam in full sun. Partial shade is also tolerated. Rarely requires pruning except to restrict spread, and is an excellent pot plant using a standard, well-drained soil mix with light dressings of low-phosphorus, slow-release fertiliser. Native plant nurseries sometimes carry this species.

Propagation Seed Sets prolific seed in the wild. Germination is improved by nicking the testa before sowing. Cutting Grows readily from firm, young growth cuttings taken at most seasons. Grafting Untested.

Horticultural features G. humifusa is one of the most popular species in the G. thelemanniana complex and is valued for its dense, ground-covering habit, its hoary, grey-green foliage, and bright, pink-red, yellow-tipped flowers covering the plant in autumn and winter. Its trailing habit makes it an ideal spill-over plant for rockeries and walls and it is an excellent contrast or feature plant in the landscape. It is both long-lived and attractive and could be used more frequently in landscaping than it currently is. It is popular in gardens of people interested in native plants.

General comments G. humifusa is recognised as distinct because of its unique habit and distinctive branchlet and leaf indumentum. It appears closely related to G. preissii but shares many important features with G. delta. Until its relationships can be properly assessed, it is here recognised as a distinct species. The name G. humifusa P.M. Olde & N.R. Marriott has no association with G. humifusa A. Cunningham, a nomen nudum which Bentham (1870: 436) placed under G. laurifolia.

Addendum

Spreading Grevillea (Grevillea humifusa) Interim Recovery Plan 2003-2008

In adopting this plan under the Environment Protection and Biodiversity Conservation Act 1999 (EPBC Act), the Minister for the Environment and Heritage has approved the following modifications.

Critical Habitat
The plan identifies a broad area as critical habitat, including buffer zones of a set distance around known populations. The Threatened Species Scientific Committee does not necessarily believe that such an area qualifies as habitat critical to the survival of the species, as defined in the EPBC Act.

Recovery Criteria
For the purposes of reviewing this recovery plan under the EPBC Act, the Recovery Criteria are amended to read as follows:

Criteria for success: The number of individuals within populations and/or the number of populations have increased by 10% or more over the period of the plan's adoption under the EPBC Act.
Criteria for failure: The number of individuals within populations and/or the number of populations have decreased by 10% or more over the period of the plan's adoption under the EPBC Act.