Grevillea is a large genus of flowering plants in the family Proteaceae, containing over 360–380 species of evergreen shrubs and, rarely, small trees. The vast majority are endemic to Australia, with smaller groups of species native to New Guinea, New Caledonia, and parts of Indonesia (Sulawesi). Within Australia, grevilleas occupy an exceptional diversity of habitats and growth forms, ranging from sprawling ground covers to towering trees.
The leaves are arranged alternately along the stems and may be simple or deeply compound, taking needle-like or fern-like shapes depending on the species. Unlike most flowering plants, grevillea flowers lack petals; instead, their brightly colored, elongated styles protrude conspicuously from narrow calyx tubes, creating the characteristic spider-flower or toothbrush appearance that makes many species instantly recognizable. Flowers are zygomorphic and typically produced in pairs along racemes. The fruit is a thin-walled follicle that splits along one side to release one or two seeds.
Grevilleas are important components of Australian ecosystems. Bird-pollinated species — displaying vivid red, pink, and orange hues — produce abundant nectar that sustains honeyeaters and lorikeets. Cream- or white-flowered species attract insects, including bees, flies, and beetles. Several species are significant sources of food for Aboriginal Australians, who traditionally gathered nectar and used parts of the plant for medicine, tools, and ceremony.
The genus is widely cultivated in temperate and subtropical gardens worldwide. Plants generally require full sun, excellent drainage, and low-phosphorus, acidic soils. Most species are drought-tolerant but frost-sensitive; cold-hardy exceptions such as Grevillea victoriae have expanded the genus's usefulness in cooler climates. Gardeners should handle grevilleas carefully, as the flowers, bark, and leaves of many species contain resorcinol compounds that can cause delayed allergic contact dermatitis resembling a poison-ivy reaction.
Conservation is a growing concern: as of 2025, the IUCN lists 135 Grevillea species in threatened categories, with 30 considered Critically Endangered. Habitat clearing, altered fire regimes, and invasive species are the primary drivers of decline.
Etymology
The genus name Grevillea honors Charles Francis Greville (1749–1809), an 18th-century British patron of botany and co-founder of the Royal Horticultural Society. The genus was formally described in 1809 by Joseph Knight based on an unpublished manuscript by Robert Brown; Knight initially spelled the name Grevillia, but Brown corrected the spelling to Grevillea in 1810.
Distribution
Grevillea is overwhelmingly an Australian genus, with more than 380 species endemic to the continent across nearly every habitat except alpine zones, swamps, and saline soils. Outside Australia, the genus extends into the Pacific: four species occur in New Guinea, ten are endemic to New Caledonia, and one is endemic to Sulawesi in Indonesia. In cultivation, grevilleas have been widely established in temperate and subtropical regions globally, and Grevillea robusta (silky oak) has naturalized and become invasive in New Zealand, French Polynesia, Zimbabwe, South Africa, Hawaii, and parts of Florida.
Ecology
Grevilleas are major nectar producers and play a significant role in supporting wildlife. Species pollinated by birds — predominantly honeyeaters and lorikeets — produce flowers in vivid reds, pinks, and oranges with high nectar volumes. Insect-pollinated species tend toward white or cream coloration, smaller flower size, and fragrance attractive to bees, flies, and beetles. The genus's year-round or near-year-round flowering provides critical food resources in Australian heathlands and woodland ecosystems. Some species are ecologically problematic outside their native range: Grevillea robusta is documented as invasive in multiple regions.
Cultivation
Grevilleas thrive in full sun with well-drained, acidic, low-phosphorus soils; added phosphorus fertilizers can be toxic to the plants and should be strictly avoided. Most species are drought-tolerant once established, with a medium growth rate, and can flower across any season depending on species or cultivar. The majority are frost-sensitive and suited to temperate or subtropical climates. Grevillea victoriae is a notable cold-hardy exception and has been successfully grown along the Pacific coasts of California and Oregon. In colder climates, container growing allows plants to be moved indoors before freezing temperatures arrive; grevilleas also perform well as houseplants in bright light or in greenhouse and atrium settings.
Popular cultivars include 'Robyn Gordon', which flowers year-round in subtropical climates, and 'Canberra Gem', which holds the RHS Award of Garden Merit. Gardeners must handle all plant parts with care, as grevilleas produce resorcinol compounds in their bark, flowers, and leaves that can trigger delayed allergic contact dermatitis — symptoms include intense itching, streaking, and blisters. The reaction is chemically similar to poison-ivy (urushiol) sensitivity.
Conservation
As of 2025, the IUCN Red List recognizes 135 Grevillea species in a threatened category, including 30 listed as Critically Endangered — making the genus one of the most conservation-significant in the Australian flora. Primary threats are habitat clearing for agriculture and urban development, altered fire regimes that disrupt post-fire regeneration, and competition from invasive plant species. The large number of threatened taxa reflects the genus's high endemism: species with narrow geographic ranges are particularly vulnerable to localized disturbance.
Cultural Uses
Aboriginal Australians have long used grevilleas for a wide range of purposes. Nectar consumption is the most widespread food use, with flowers sucked directly or soaked in water to make sweet drinks. Beyond food, various species have been applied medicinally and used to make tools and implements; some species also hold ceremonial significance. In colonial times, the timber of Grevillea robusta was valued for its fine grain: a Pembroke table veneered in grevillea wood was made in the 1790s for Commissioner of the Royal Navy Sir Andrew Snape Hamond and is now held in the National Museum of Australia.
Taxonomy Notes
Grevillea belongs to the family Proteaceae, order Proteales, class Magnoliopsida. The accepted author citation is Grevillea R.Br. ex Knight, with the protologue published in Cultivated Proteeae (Cult. Prot.: 120, 1809). Several earlier generic names are now treated as synonyms, including Anadenia R.Br. (1810), Lysanthe Salisb. ex Knight (1809), Stylurus Salisb. ex Knight (1809), Manglesia Endl. (1839), Lissostylis (R.Br.) Spach (1841), Plagiopoda Spach (1841), Ptychocarpa Spach (1841), and Fitchia Meisn. (1855).
