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25 Nov 2022

Plant of the month: Cotinus coggygria

Written by Niki Douglas, PLANTS Project Inventory Officer
A close-up of some beautiful leaves of a plant. They are a purple-pink colour with dark splodges and pink veins. The sun is shining through them.
Cotinus coggygria (smoke bush)
While auditing the garden at Crathes Castle, Niki Douglas (Inventory Officer for the PLANTS project) was impressed by the beauty of Cotinus coggygria (the smoke bush).

There are several plants displaying their rich autumnal glow at Crathes Castle this month, including Cotinus coggygria Rubrifolius Group and Cotinus coggygria ‘Royal Purple’. These plants can be found in the Red and Upper Pool gardens, stubbornly holding their leaves in defiance of winter.

Cotinus coggygria (also known as Rhus cotinus) is a deciduous shrub or small tree, with rounded leaves. It originates from a wide-ranging area stretching across southern Europe all the way to Asia. Cotinus coggygria is in the Anacardiaceae family, commonly known as the cashew or sumac family, as reflected in some of its popular names such as Venetian sumach and Turkish sumac. Another common name is dyer’s sumach because a yellow dye (called young fustic) can be extracted from the wood of Cotinus coggygria – this was highly valued in the Middle Ages.

A red-leaved bush grows in a bed in a walled garden. A lawn area and old stone building can be seen in the background.
Cotinus coggygria (smoke bush) at Crathes

Today, it is predominantly grown for its show-stopping fiery autumn colours and the feathery, billowing clouds of its high summer flowers. These paniculate (growing in clusters along a branch) flower heads are loose and open, with many branching stems. The small inflorescences produce a relatively sparse amount of seed, with the non-flowering terminals becoming hairy as the season progresses. These contribute to the visual ‘smoky’ effect and are the reason Cotinus coggygria is referred to as the smoke bush.

The purple-leaved cultivars of Cotinus coggygria have become the most popularly grown, with the best leaf colour produced in full sun or partial shade. They can be hard pruned in late winter to encourage larger leaf sizes, providing stunning arched branches of yellows, oranges, rich reds and deep purples the following autumn. The intense and diverse colours and patterns produced by carotenoids (natural pigments), such as xanthophyll (yellows) and beta-carotene (oranges), remain longer in the leaf and become more prominent as the chlorophyll recedes. Another pigment contributing to the colours is anthocyanin (deep reds and purples). This is created by excess sugars becoming trapped within the leaf as they naturally detach and fall from the branch.

A neighbour told me his very young daughter calls a cultivar of Cotinus I have growing in my garden (C. coggygria ‘Young Lady’) the ‘Tiger Tree’. He said he wasn’t sure why, but I like to think she noticed the fabulous striped patterns in gold and darker bands on the leaf in autumn!

Cotinus coggygria can be found in many other National Trust for Scotland gardens, including Broughton House, Culzean Castle and Falkland Palace. The next time you visit, be sure to look out for this beautiful plant.

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