Both plane tree (Platanus) & oriental sweetgum (Liquidambar orientalis) are widely cultivated as street trees in cities like Sydney. They have thick and wide foliage giving good shades. The branches do not fall off easily and are safe to the road users. Both trees flower in late spring.

The two trees are not related (they belong to different Genus, Family and Order) but both produce flower heads. Both of them are deciduous. In autumn, the leaves turn yellow and orange red. They shed their leaves.

The leaves of the plane tree turned yellow
The leaves of the plane tree turned yellow

 Plane trees (Platanus)

Plane trees (Platanus) are native to the Northern Hemisphere. They are tall, reaching 30–50 m in height. The hybrid London Plane (a hybrid between oriental plane and American sycamore) has proved particularly tolerant of urban conditions.

A plane tree planted in a Sydney street
A plane tree planted in a Sydney street

The mature bark peels off or exfoliates easily in irregularly shaped patches, producing a mottled, scaly appearance.

The bark of the stem has a mottled and scaly appearance. The colour is pale grey and cream white.
The bark of the stem has a mottled and scaly appearance. The colour is pale grey and cream white.

The flowers are reduced and are borne in balls (globose heads); 3–7 hairy sepals may be fused at the base, and the petals are 3–7 and are spatulates (spoon-shaped). Male and female flowers are separate, but borne on the same plant. The male flower has 3–8 stamens,  the female has a superior ovary with 3–7 carpels. Plane trees are wind-pollinated. Male flower-heads fall off after shedding their pollen.

The female flower head is made up of hundreds of little female flowers.
The female flower head is made up of hundreds of little female flowers.
A single flower has been separated from the flower head. The stigma at the top has dried out as seen under a microscope.
A single flower has been separated from the flower head. The stigma at the top has dried out as seen under a microscope.

After being pollinated, the female flowers become achenes (small, one-seeded dry fruit) that form an aggregate ball.

The female flowers become achenes that form an aggregate ball. The ball is 2.5–4 cm in diameter.
The female flowers become achenes that form an aggregate ball. The ball is 2.5–4 cm in diameter.

 

There is a tuft of many thin stiff yellow bristle fibres attached to the base of each achene.

The female flowers become achenes that form an aggregate ball. The ball is 2.5–4 cm in diameter.
Achenes dispersed from the aggregate ball

 

The achenes are ripen and they are ready to be dispersed by the wind.
The achenes are ripen and they are ready to be dispersed by the wind.
The sequential development of a female flower head to a ripe fruit with dry achenes dispersed (from left to the right)
The sequential development of a female flower head to a ripe fruit with dry achenes dispersed (from left to the right)

Oriental sweetgum (Liquidambar orientalis)

Oriental sweetgum (Liquidambar orientalis), commonly known as Turkish sweetgum is native to the eastern Mediterranean region in the flood plains of southwestern Turkey and on the Greek island of Rhodes.

The oriental sweetgum tree (Liquidambar)
The oriental sweetgum tree (Liquidambar)
The bark of the tree trunk of Liquidambar containing many cracks
The bark of the tree trunk of Liquidambar containing many cracks
A female flower head
A female flower head
A dried fruit formed from a flower head of the previous year
A dried fruit formed from a flower head of the previous year

 

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Liquidambar leaves turn reddish orange in autumn
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Close-up of the above tree
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Reddish orange leaves and fruits

Comparisons between Platanus & Liquidambar

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Beautiful autumn scene of plane trees & oriental sweetgum in a Sydney street taken on 3 June 2016

Bibliography :

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

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

 

 

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