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A cloud of lavender-blue flowers covers the entire crown of a jacaranda tree.

Jacaranda is native to tropical and subtropical regions of Central America and South America in places like Cuba, Jamaica and Brazil. It has been planted widely in Asia, South Africa and Australia.

The name is believed to be of Guarani origin, an indigenous language of South America meaning fragrant.

Jacaranda belongs to a genus in the family Bignoniaceae. The scientific name of the commonly planted jacaranda tree in Sydney is Jacaranda mimosifolia. The species are large trees ranging in size from 20 to 30 m tall. The leaves are bipinnate in all species. Leaves appear with or just after the flowers. The bark of the tree is rough with a lot of tiny rectangular cracks .

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The bark of a jacaranda tree

The leaves are deciduous, the foliage turning yellow before falling in late winter to early spring.

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The leaves turn yellow and fall before flowering starts

The flowers

During late spring around the mid October to early November in Sydney, around the time of the Higher School Certificate Examination, flowers appear in terminal clusters, in panicles of inflorescence, each flower with a five-lobed purple-blue or lavender-blue corolla.

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A panicle has a branching main axis and bears many flowers. This image shows young panicles of early developmental stages.
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The purple blue flowers are arranged in large panicles or inflorescence. The petals fused into a corolla tube.
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A flower is cut opened to show the long staminode, 4 stamens and a pistil

The flower has a staminode that is much longer than the stamen. (In many flowers, a staminode is often rudimentary, sterile or abortive stamen, which does not produce pollen.) In jacaranda the staminode is long and conspicuous.  It contains numerous glandular trichomes. Secretions from the glandular trichomes attract honey bees and other insects. It plays an important role in pollination.

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The tip of a staminode with numerous glandular trichomes as seen under microscope

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The cross section of the ovary with ovules as seen under microscope

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Half-flower diagram of a jacaranda flower

The fruit and seeds

The fruit is an oblong to oval flattened seed capsule containing numerous slender seeds.

 

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A pair of fruit (flattened seed capsules) 6 months after fertilization. The fruit wall is green.
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The same pair of fruit seen from a different angle.
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A pair of fruit (flattened seed capsules) 12 months after fertilization. The wall is dry and dark brown in colour.
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A fruit (seed capsule) has been opened to show the seeds inside. There are about 70 seeds in this capsule.

Papery wing of the seeds help the seeds to flutter and spin as they are carried by the wind.

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Papery, winged seeds inside a seed capsule

 

This species thrives in full sun and sandy soils, explaining their abundance in warmer climates.

Plantation of Jacaranda

Jacaranda can be seen lining avenues in some areas.

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The two sides of a street in Kirribilli, Sydney are planted with jacaranda trees

 

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The jacaranda trees are in full bloom

The city of Grafton on the north coast of New South Wales has a Jacaranda festival during the period of full bloom. A street parade, local public holiday and a series of events are held.

The tree canopies in some of Sydney’s north shore and around the harbour have a purple glow during late spring.

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The lavender-blue of jacaranda flowers contrasts beautifully with the orange red roof tiles.
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The eastern suburbs in Sydney with purple glow during the jacaranda season.

In the Main Quadrangle of the University of Sydney there was a solitary old jacaranda tree planted in 1928, and the saying goes: “If you haven’t started studying by the time the jacaranda starts blooming, it’s too late”! Unfortunately the tree collapsed in early 2016.

The solitary old jacaranda tree in the quadrangle of the University of Sydney
The solitary old jacaranda tree in the quadrangle of the University of Sydney

 

Sister Irene Haxton ran a maternity hospital in Caringbah during the 1950s and 1960s. She also grew and nurtured jacaranda seedlings.

Every one of the thousands of babies born at the hospital were sent home with a jacaranda seedling which was most probably planted in honour of the new family member. Many jacarandas on private properties in the local area might be attributed to Sister Haxton.

Drawings of Jacaranda trees

A sketch of jacaranda trees by Patrick
A sketch of jacaranda trees by Patrick
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A sketch of jacaranda trees in full bloom on a hillside in the lower north shore, Sydney

Illawarra flame tree and southern silky oak tree planted near jacaranda trees

Illawarra flame tree (Brachychiton acerifolius)  flowers more or less the same time as jacaranda. The red flowers contrast beautifully with the lavender-blue flowers of jacaranda. The two trees are planted close to each other.

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When Illawarra flame tree and jacaranda bloom at the same time, the effect is truly spectacular

Flowers are bright red in colour. The showy red-coloured structures are perianth ( fusion of sepals and petals). The perianth is tubular, 5-lobed. The flowers are arranged in panicles. The pod-like fruit (also known as follicles) are dark brown, wide and about 10 cm long.

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Panicles of red bell-shaped flowers and 3 follicles (seed pods)

Both jacaranda and Illawarra flame trees are good subjects for painting.

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Mid-spring scene in Waverton, NSW. Artist : Allan Hanson FRAS, circa 1993, 40 x 54 cm, oil on canvas board.

Southern silky oak (Grevillea robusta) blooms in late spring around the same time as jacaranda.

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Southern silky oak tree with yellow flowers in full bloom

Its flowers are golden-orange bottlebrush-like blooms, between 8–15 cm long on a 2–3 cm long stem and are used for honey production. The petals and sepals are fused together to form tepals. They are split into 4 lobes. The stigma and the style of the pistil (female part) are long, protruding out and very conspicuous. The style and stigma, with attached pollen, is called the ‘pollen presenter’. This is the conspicuous part of the flower.

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Golden-orange bottlebrush-like flowers in inflorescence. The pistils are long and conspicuous.
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Flowers are further magnified to show the perianths and the long protruding pistils

The seeds mature in late winter to early spring, fruiting on dark brown leathery dehiscent follicles, about 2 cm long, with one or two flat, winged seeds.

Poem / Song related to the Jacaranda tree

Christmas where the gum trees grow

There is no frost and there is no snow

Christmas in Australia’s hot

Cold and frosty is what it’s not

When the bloom of the Jacaranda tree is here

Christmas time is near

From England came our Christmas fare

They even said what Santa should wear

But here down under for summers cool

Santa should dip in a swimming pool

Christmas where the gum trees grow

There is no frost and there is no snow

Christmas in Australia’s hot

Cold and frosty is what it’s not

When the bloom of the Jacaranda tree is here

Christmas time is near

Santa rides in a sleigh on snow

But down here where the gum trees grow

Santa should wear some water ski’s

And glide around Australia with ease

Christmas where the gum trees grow

There is no frost and there is no snow

Christmas in Australia’s hot

Cold and frosty is what it’s not

When the bloom of the Jacaranda tree is here

Christmas time is near

To ride around the bush where it’s dry

To cart all the presents piled so high

A red nosed reindeer would never do

Santa should jump on a kangaroo

Christmas where the gum trees grow

There is no frost and there is no snow

Christmas in Australia’s hot

Cold and frosty is what it’s not

When the bloom of the Jacaranda tree is here

Christmas time is near

CHRISTMAS WHERE THE GUM TREES GROW (Val Donlon / Lesley Sabogal) (poem)

 

Acknowledgements :

I would like to thank Ms Seanna McCuneBotanical Information Service, National Herbarium of New South Wales for her guidance and kind support.

I would like to thank Mrs Jane Theau of Workshop Arts Centre for her kind advice and Mr K W Yiu of University of Sydney for providing me with the photograph of the Jacaranda tree in University of Sydney.

Bibliography :

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

https://zh.wikipedia.org/wiki/%E8%93%9D%E8%8A%B1%E6%A5%B9 (藍花楹)

http://www.ncbi.nlm.nih.gov/pmc/articles/PMC2712375/ (staminode)

http://blogs.usyd.edu.au/sydneylife/2006/10/the_perils_of_ignoring_a_bloom.html

http://www.theleader.com.au/story/2686244/colour-my-world-blooming-jacarandas-a-dazzling-delight/

http://www.smh.com.au/nsw/university-of-sydney-clones-iconic-quadrangle-jacaranda-tree-20141116-11np06

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

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

http://lyricsplayground.com/alpha/songs/xmas/christmaswherethegumtreesgrow.shtml

https://www.youtube.com/watch?v=uvazmEwP-8o

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