Callistemon is a member of the myrtle (Myrtaceae) family. It was first described as a genus in 1814. Callistemon species have commonly been referred to as bottlebrushes because of their cylindrical, brush like flowers resembling a traditional bottle brush.

The botanical name Callistemon is derived from the Greek words kallos, meaning beauty, and stemon, meaning stamen, describing the coloured stamens, the showy part of the flowers.

The entire genus is endemic to Australia and is widely cultivated in many other places. They are long lived and require minimal maintenance. Some species are even drought-resistant. They are widely used in ornamental landscaping.

In Australia, flowering is normally in spring and early summer (October–December), but conditions may cause flowering at other times of the year. The flowers attract native birds, especially honey eaters. The obvious parts of the flower masses are stamens, with the anther at the tip of the filament. The corolla is inconspicuous and green in colour. The calyx is even more minute.

Each flower head produces a profusion of 3-chambered seed capsules around a stem. They remain on the plant with the seeds enclosed until stimulated to open when the plant dies or fire causes the release of the seeds. A few species release the seeds annually.

 

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A mature inflorescence and an inflorescence in flower bud stage

 

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The inflorescence in flower bud stage. The long red filament of the stamens are coiled up.

 

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The inflorescence is in full bloom. Some flowers have been removed to show individual flowers of the inflorescence.

 

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An individual flower separated from the inflorescence

 

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An individual flower

 

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On the left: the pistil (consisting of the stigma and red style), the green petal, the green calyx lobes and calyx. On the right: a bundle of stamens (consisting of anthers and filaments)

 

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5 small green petals, green calyx lobes and the green calyx tube

 

 

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The anthers and the red filaments
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The anthers

 

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The ovary has been cut longitudinally into halves showing the ovules inside.
The ovary has been cut transversely. The 3 carpels contain numerous ovules. inside
The ovary has been cut transversely. The 3 carpels contain numerous ovules inside.

 

 

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Section through the flower (some stamens have been removed)

 

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The stamens withered and dropped off from the flowers
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Fruiting capsules developing

 

 

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Fruiting capsules
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Fruiting capsules

 

Botanical Drawings :

Fisher, Celia (2013) The Golden Age of Flowers The British Library, ISBN 978 07123 5895 8
From Fisher, Celia (2013) The Golden Age of Flowers The British Library, (ISBN 978 07123 5895 8)

 

Fisher, Celia (2013) The Golden Age of Flowers The British Library, ISBN 978 07123 5895 8
From Cronin, Leonard (1987) Key Guide to Australian Wildflowers, A Reed Book (ISBN 0 7301 0191 6)

 

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From Cronin, Leonard (1987) Key Guide to Australian Wildflowers, A Reed Book (ISBN 0 7301 0191 6)

 

Bibliography :

https://en.wikipedia.org/wiki/Callistemon 

http://http://www.burkesbackyard.com.au/fact-sheets/in-the-garden/flowering-plants-shrubs/bottlebrush/

Cronin, Leonard (1987)  Key Guide to Australian Wildflowers A Reed Book (ISBN 0 7301 0191 6)

Fisher, Celia (2013) The Golden Age of Flowers The British Library (ISBN 978 07123 5895 8)

Wrigley, John W and Murray Fagg (1993) Bottlebrushes, Paperbarks & Tea Trees and all other plants in the Leptospermum alliance, Angus & Robertson (ISBN 0-207-16867-9)