Grevillea humilis is an erect to spreading shrub that usually grows less than 1 metre but may reach just over 1 metre in height, with a spread to 2 metres wide.The species is said have rhizomes and thus sucker.
It has a coastal distribution, found on the central coast and north coast subdivisions of NSW. There is the odd record in the Wollongong and Sydney-areas, but the main populations are from Wyong, through Newcastle to around Clarence Town; then a large disjunction to between Brooms Head and Woodburn (south of Lismore). There are records in Queensland, just north of Caboolture.
It can be found growing in dry sclerophyll woodland as well as swampy areas on heavy clay soils, as well as sandstone and ironstone substrates in shrubby heath and woodlands on coastal headlands.
Leaves are irregularly arranged on stems or in distinct clusters of 3, variable between populations, to 50 mm long and to 6 mm wide, narrow-elliptic to linear or oblanceolate to obovate, mid to dark green and with recurved margins, with some forms have wider short leaves and others lone narrow leaves.
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 produce the inflorescences mostly at the terminals, beyond the foliage, which differs to the closely related Hakea.
This species is a spider-flower, with spider-inflorescences white to pink in colour, about 2 cm by 2 cm in size. Peak flowering occurs in spring and summer with sporadic flowering at other times.
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, flowers are to 1.5 cm long, with dark-pink, pink and white tones.
The fruit is a follicle with rough protuberances, to 1 cm long.
This plant is known to be cultivated and can be grown reliably.
In our cold climate garden, our specimen has shown no signs of suckering.
Light, occasional pruning will prevent plants becoming straggly.
Grevillea humilis could be grown as a foreground plant in native garden beds and also the species would be a useful addition to rockeries and cottage gardens. There is also a prostrate form marketed as ‘Coastal Gem’ which is sold as a groundcover.
It is a very similar plant to Grevillea linearifolia and can likley be grown in similar conditions, on a well-drained soil in part shade to full sun. This species can be found in swampy areas,
Grevillea humilis propagates readily from cuttings. Grevilleas are propagated by three principal methods; seed, cuttings and grafting. To maintain desirable characteristics of a particular plant, vegetative propagation (e.g. cuttings or grafting) must be used. This also applies to propagation of named cultivars.
In Volume 2 of The Grevillea Book by Olde and Marriott the species is described as the coastal form of Grevillea linearifolia.
There are 3 subspecies currently reocgnised in NSW:
It is likely these subspecies need further taxonomic investigation.
Most grevilleas regenerate from seed after fire. Some can reshoot from buried rhizomes. This species is known to sucker after disturbance such as fire.
Grevillea flowers were a traditional favourite among First Nations Peoples of Australia 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”.
Grevillea is a diverse genus of about 365 species with about 357 occurring in Australia. Some species occur in New Caledonia, Indonesia and New Guinea. NSW currently has about 85 species although with a lot of subspecies and some informal taxa recognised.
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.
humilis – Latin referring to ‘humble’ meaning ‘low growing’ – referring to the general low height of the species.
(subsp. maritima) – Latin – “maritime” or “growing by the seashore”.
(subsp. lucens) – Latin – meaning “shining” – referring to the manner in which the sunlight sparkles off the hairs on the undersides of the leaves.
This species is not considered to be at risk of extinction in the wild.
NSW Flora Online (PlantNET) – Grevillea humilis profile page https://plantnet.rbgsyd.nsw.gov.au/cgi-bin/NSWfl.pl?page=nswfl&lvl=sp&name=Grevillea~humilis
Wikipedia – Grevillea humilis profile page https://en.wikipedia.org/wiki/Grevillea_humilis
Burringbar Rainforest Nursery – Grevillea humilis ‘Coastal Gem’ sales page https://burringbarrainforestnursery.com.au/plant-search/grevillea-humilis-coastal-gem/