Plant of the month: Thujopsis dolabrata

The species was first introduced to the UK from Japan in the 1850s and it is thought that this tree was planted at Culzean c1880, around 100 years after the walls of the garden were built. This tree can be slow to get going after planting, and so to encounter one of such impressive size is quite special. Our Culzean tree is believed to be one of the most multi-stemmed examples of the species in Europe, although there has been some debate as to whether it is one tree or several saplings planted together.

Thujopsis dolabrata is endemic to Japan, where it grows in both lowland and montane forests to 2,000m and can withstand temperatures below -20°C. In cultivation it thrives in high rainfall areas and the finest specimens in the UK grow on the west coast of Scotland, Wales and Cornwall.

At Culzean it is a firm favourite with children who enjoy weaving their way through the many trunks. If you stop quietly under the tree for a while you may be lucky enough to hear the drumming of a great spotted woodpecker, which often frequents the upper branches.

While the trunk provides the initial wow-factor, a more hidden but just as beautiful characteristic of Thujopsis dolabrata is seen on the underside of the leaves: the white markings of the stomata. These are so vivid and intricate that they almost look as if they have been painted on. This unique pattern is so distinctive that it cannot be confused with any other conifer. The evergreen leaves are held in flattened sprays. From above, they are glossy green, thick and scaly and have been said to resemble lizard’s skin. As with most conifers, if you rub the leaves between your fingers a resinous aroma is released.

You may see some small patches of yellow on the leaves at Culzean as this tree is in fact a variegated form. First Gardener Ian says the variegation was more noticeable 20 years ago, although it is common for this reversion to take place.

Another feature to look out for is the cones. The larger female cones, where the seeds develop, are initially green. When the cones ripen, they become brown and open to release the seeds, which are carried by the wind. The male pollen cones are more fleeting and much smaller; once the pollen has been released from them in late spring, they wither away.

As with all trees at Culzean, regular tree inspections are carried out to assess the health of the tree. In 2018 two limbs needed to be removed, and during the following inspections it was noted how slowly the pruning cuts were healing. This, together with thinning growth high in the canopy, made it clear the tree is lacking vigour. Head Gardener Iain and his team have applied a rock dust and liquid mycorrhizal fungi to the roots to try and restore vigour. Exposed surface roots and compaction may be the cause, and ways to reduce this are being considered so that the tree keeps growing well at Culzean for many years to come.

This is a wonderful tree and full of character; be sure to pay it a visit when you are next at Culzean.

Plant Listing At the National Trust for Scotland (PLANTS) is a Trust-wide garden inventory project. It will result in an accurate database that records plant collections in our 39 major gardens and designed landscapes. Three regionally based project teams, with central-based support, will inventory the plants over the next three years.

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