Grevillea (/ɡrɪˈvɪliə/),[2] commonly known as spider flowers,[3] is a genus of about 360 species of evergreen flowering plants in the family Proteaceae. Plants in the genus Grevillea are shrubs, rarely trees, with the leaves arranged alternately along the branches, the flowers zygomorphic, arranged in racemes at the ends of branchlets, and the fruit a follicle that splits down one side only, releasing one or two seeds.
Description
Plants in the genus Grevillea are shrubs, rarely small trees with simple or compound leaves arranged alternately along the branchlets. The flowers are zygomorphic and typically arranged in pairs along a sometimes branched raceme at the ends of branchlets. The flowers are bisexual, usually with four tepals in a single whorl. There are four stamens and the gynoecium has a single carpel. The fruit is a thin-walled follicle that splits down only one side, releasing one or two seeds before the next growing season.[3][4][5][6][7]
There are over 350 species which are endemic to Australia. Five other species are endemic to areas outside Australia. Three of these (G. exul, G. gillivrayi, and G. meisneri) are endemic to New Caledonia, while G. elbertii and G. papuana are endemic to Sulawesi and New Guinea respectively. Two other species, G. baileyana and G. glauca, occur in both New Guinea and Queensland.
Distribution and habitat
Grevilleas grow in most habitats, although few grow in alpine areas, in swamps or saline soils. Most species are endemic to Australia but three species grow in New Guinea, (G. papuana is endemic), three are endemic to New Caledonia and one species (G. elbertii) is endemic to Sulawesi in Indonesia.[4]
Ecology
Grevilleas are good bird-attracting plants. Honeyeaters in particular are common visitors. They are also used as food plants by the larvae of some Lepidoptera species, including the dryandra moth and Pieris rapae (small butterfly or cabbage white butterfly).
The main threats to grevillea species include habitat clearing for roads, mining, housing, agriculture and grazing, altered fire regimes and competition with both invasive and native species.[12]
Many species of grevilleas are popular garden plants, especially in Australia but also in other temperate and subtropical climates. Many grevilleas have a propensity to interbreed freely, and extensive hybridisation and selection of horticulturally desirable attributes has led to the commercial release of many named cultivars. Among the best known is 'Robyn Gordon', a small shrub up to 1.5 m (5 ft) high and wide which can flower 12 months of the year in subtropical climates. The cultivar 'Canberra Gem' has gained the Royal Horticultural Society's Award of Garden Merit.[14][15]
They can be grown from soft tip cuttings from December–March (in the Southern Hemisphere) or fresh seed. Many harder-to-grow species can be grafted onto hardy rootstock such as Grevillea robusta.
There is an active Grevillea Study Group in the Australian Native Plants Society for people interested in grevilleas, both for uses in horticulture and for conservation in the wild.
Grevillea flowers were a traditional favourite among the Aboriginal 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".
Drinking nectar direct from the flower is best avoided as some commonly cultivated grevillea species produce flowers containing toxic cyanide.[16][17]
^"EPBC Act List of Threatened Flora". Australian Government Department of Climate Change, Energy, the Environment and Water. Retrieved 10 January 2024.
^McKenzie, R., Cyanide, Strychnine Bush and Other Poisonous Hazards in the Queensland Flora: Have We Progressed Since C.T.White?, C.T.White Memorial Lecture for 2002 [1]
^Everist, S.L., Poisonous Plants of Australia, Angus & Robertson, 1974.
