Darwinia biflora is a plant in the myrtle family Myrtaceae and is endemic to New South Wales. It is an erect, often straggly shrub with flattened, glabrous leaves, and flowers which are arranged in pairs. The flowers are greenish in colour but each is surrounded by two purple-red bracteoles and have a long yellow-green style projecting out of the flower tube. The species only occurs in the Sydney region in a few places where shale-capped ridges intergrade with Hawkesbury sandstone.
| Darwinia biflora | |
|---|---|
Scientific classification 
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| Kingdom: | Plantae |
| Clade: | Tracheophytes |
| Clade: | Angiosperms |
| Clade: | Eudicots |
| Clade: | Rosids |
| Order: | Myrtales |
| Family: | Myrtaceae |
| Genus: | Darwinia |
| Species: | D. biflora
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| Binomial name | |
| Darwinia biflora | |
| |
| Occurrence data from AVH | |
| Synonyms[1] | |
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Darwinia taxifolia var. biflora Cheel | |
Description
editDarwinia biflora is an erect, sometimes spreading, often straggly shrub which grows to a height of 0.2–0.8 metres (0.7–3 ft). The leaves are glabrous and arranged in a decussate pattern along the branches. The leaves are 6–10 millimetres (0.2–0.4 in) long, flattened and often pressed against the branches.[2][3][4]
The flowers are arranged on stalks less than 1 millimetre (0.04 in) long near the ends of the branches, usually in pairs. When they open, the flowers are tubular in shape, white to pink in the upper parts and green in the floral tube. The flower tube is 5–8 millimetres (0.2–0.3 in) long and is surrounded by leaf-like bracts 1–8 millimetres (0.04–0.3 in) long and two purple-red bracteoles 5–8 millimetres (0.2–0.3 in) long which fall off after the flower has opened. Stamens and staminodes are enclosed within the flower tube but the style is 10–14 millimetres (0.4–0.6 in) long, yellow-green or red, straight or slightly curved and projects out of the tube. Flowering occurs throughout the year but mainly between May and August and is followed by the fruit which is a nut about 1–1.5 millimetres (0.04–0.06 in) in diameter.[2][3][4]
Taxonomy
editThe first formal description was by Edwin Cheel who gave the plant the name Darwinia taxifolia var. biflora. The description was published in 1922 in Journal and Proceedings of the Royal Society of New South Wales.[5][6] In 1962, Barbara Briggs raised it to species status and published the change in Contributions from the New South Wales National Herbarium.[7][8]
The specific epithet (biflora) is derived from the Latin prefix bi- meaning "two"[9]: 141 and the Latin word flos meaning "flower".[9]: 338
Distribution and habitat
editAlthough there are herbarium specimens of this species from further afield, all the present populations occur in the urban areas of Sydney between Maroota and North Ryde. It grows in heath on sandstone ridge tops or in woodland where the sandstone intergrades with shale. Ninety of the 240 known sites where the species occurs are in national parks or other reserves but the remainder are in habitats often favoured for residential development.[2][3][4]
Ecology
editIndividual plants of Darwinia biflora are thought to live for 15 to 20 years. The plants usually self-pollinate and insects have rarely been observed visiting the flowers. Seed is usually not produced until the plants are about 5 years old but the viability of seed is high and although fire kills the plant, many new seedlings appear after fire.[4]
Conservation
editDarwinia biflora is listed as a vulnerable species in New South Wales and in terms of the Australian Government Environment Protection and Biodiversity Conservation Act 1999.[10]
References
edit- ^ a b "Darwinia biflora". Australian Plant Census. Retrieved 26 July 2022.
- ^ a b c Wilson, Peter G. "Darwinia biflora". Royal Botanic Garden Sydney:PlantNET. Retrieved 9 September 2016.
- ^ a b c "Approved Conservation Advice for Darwinia biflora" (PDF). Australian Government Department of the Environment. Retrieved 26 March 2019.
- ^ a b c d "Approved Recovery Plant Darwinia biflora" (PDF). NSW Government Department of the Environment. Retrieved 26 March 2019.
- ^ "Darwinia taxifola var. biflora". APNI. Retrieved 9 September 2016.
- ^ Cheel, E. (1922) Notes on the species of the genera Darwinia, Homoranthus and Rylestonea in New South Wales, Queensland and South Australia. Journal and Proceedings of the Royal Society of New South Wales 56: 72.
- ^ "Darwinia biflora". APNI. Retrieved 9 September 2016.
- ^ Briggs, B.G. (1962) in Anderson, R.H. (ed.), The New South Wales Species of Darwinia. Contributions from the New South Wales National Herbarium 3(3): 144, fig. 2a (map)
- ^ a b Brown, Roland Wilbur (1956). The Composition of Scientific Words. Washington, D.C.: Smithsonian Institution Press.
- ^ "Darwinia biflora - profile". NSW Government Department of the Environment and Heritage. Retrieved 9 September 2016.