Grevillea shiressii is a shrub, to 5 metres tall, by several metres wide.
It is a very rare species from the Central Coast of NSW where it grows near watercourses that enter the Hawkesbury River (Mullet Creek and Mooney Mooney Creek); from between Brooklyn and Gosford, to north-west of Gosford. It grows in wet sclerophyll forest on Hawkesbury Sandstone soils.
It is listed as being threatened with extinction in NSW.
Leaves are to 20 cm long by 3 cm wide, hairless, with prominent veins running inside the leaf margins.
A grevillea inflorescence is technically a cluster of paired flowers, termed a conflorescence with the overall structure forming a raceme-like appearance. Grevillea species exhibit 3 main inflorescence structures:
1. A cylindrical to ovoid raceme (with flowers emerging around a 360° radius)
2. A single-sided raceme (with flowers produced on only one side, resembling a tooth-brush)
3. A condensed or clustered raceme (usually as long as it is wide, with species referred to as the spider-flowers).
Grevillea mostly produce the inflorescences at the terminals, beyond the foliage, which differs to the closely related Hakea.
This species falls in the area of having spider-shortly cylindrical inflorescences, with mixed colours of green, blue-grey, orange-cream and red, appearing predominantly in spring. Each cluster is composed of 2 to 9 individual flowers and measures around 6 x 4 cm overall.
Individual flowers are composed of 1 carpel (female part) where the style and stigma protrude out; 4 stamens hidden away in the perianth; and the perianth (petals and sepals collectively) which connects to a pedicel. Proteaceae flowers do not have any discernible petals or sepals (having only one whorl) and so these are referred to as “tepals” of which there are 4. In this species, the perianth is up to 10 mm long; green-cream; ageing to blue-grey, without hairs.
The carpels are around 3 cm long, and are a mixture or red, green, and orange-cream and tipped with a green pollen-presenter. Hence, every flower has a stunning range of colours when viewed closely.
The fruit is a follicle, without hairs.
This attractive shrub reached a height two metres tall with a similar width, in five years, in our cold climate garden. The foliage is similar in appearance to the leaves of Grevillea ‘Orange Marmalade’ (see our G. ‘Orange Marmalade’ article). Our plant has proved to be very hardy in our cold climate garden. Frost does not bother the plant and once established, has proved to be very drought tolerant.
The flowers are held in axillary clusters often on older wood. The original description describes the flower colour as pale violet to greenish and tinged with pale purple-brown. This colour is unusual in grevillea flowers. Honeyeaters are attracted to the blooms. Both foliage and flowers are attractive features.
Despite its rareness, it is commonly propagated and grown (similarly to G. caleyi). It adapts well to most soils and is hardy. Plant in a part-shade spot, on a well-drained soil, for best results.
Grevillea shiressii could be grown as a component of hedges and screens.
We have found this species propagates readily from cuttings.
The original description was published in Volume 50 of the Proceedings of the Linnean Society of NSW in 1925.
The species was named after David Shiress who made the original collection with his friend the botanist William Blakely in the early 1920’s.
Grevillea is a diverse genus of about 360 species of evergreen flowering plants native to rainforest and more open habitats in Australia, New Guinea, New Caledonia, Sulawesi and other Indonesian islands east of the Wallace Line. NSW currently has about 85 species although with a lot of subspecies and some informal taxa recognised.
Grevillea flowers were a traditional favourite among First Nations Peoples for their sweet nectar. This could be shaken onto the hand to enjoy, or into a coolamon with a little water to make a sweet drink. They might be referred to as the original “bush lollies”.
Most Grevillea species will regenerate from seed after fire but can produce copping shoots. This grevillea is known to only regenerate from seed.
Grevillea – was named in honour of Charles Francis Greville (1749-1809), an 18th-century patron of botany and co-founder of the Royal Horticultural Society. He was also a British antiquarian, collector and politician who sat in the House of Commons from 1774 to 1790.
shiressii – named after David Shiress who made the original collection with his friend and botanist, William Blakely, in the early 1920’s.
This species is listed as being threatened with extinction in the wild, at both the State and Commonwealth level with the category of Vulnerable.
NSW Flora Online (PlantNET) – Grevillea shiressii profile page https://plantnet.rbgsyd.nsw.gov.au/cgi-bin/NSWfl.pl?page=nswfl&lvl=sp&name=Grevillea~shiressii
NSW Office of Environment and Heritage – Threatened Species Profiles – Grevillea shiressii profile page https://www.environment.nsw.gov.au/threatenedspeciesapp/profile.aspx?id=10380
Wrigley, J.W. & Fagg, M.I. (2001). Australian Native Plants – Propagation, cultivation and use in landscaping. 4th edition. New Holland Publishers, Pty. Ltd. Australia.