Pagoda tree - Styphnolobium japonicum

Taxonomy

Class - Equisetopsida

Subclass - Magnoliidae

Suborder - Rosanae

Order - Fabales

Family - Leguminosae

Genus - Styphnolobium

Kew’s Pagoda Tree - Styphnolobium japonicum is one of Kew’s ‘Old Lions’, one of the five trees remaining from the original 5 acre arboretum. Most of these came from the Duke of Argyll’s Whitton arboretum, being planted by William Aiton around 1702.

The first specimen to be identified came from a plant that had been cultivated in Japan. It was introduced into Britain by James Gordon¹ in 1653, and is situated by the winter garden and ice house, close to the Princess of Wales conservatory. The tree is very distinctive, as it does not grow vertically but is actually horizontal, being supported by massive steel cupped braces and a brick ‘wall’ at the base of the trunk. Despite it’s apparent precarious growing stance, it still blooms with creamy white flowers and comes into leaf, much to the delight of Kew’s visitors.

Also known as the Chinese scholar tree or Buddhist tree, possibly as it was often to be found in Buddhist temples. S. japonicum is actually a misnomer as it is actually a native of China and not ot Japan at all.

There are TWO types of Pagoda tree, Styphnolobium japonicum and Sophora japonica and even Kew’s labelling and website appears confused as to which one Kew’s Pagoda tree actually is. For that reason, this entry covers both genus.

The aforementioned Styphnolobium japonicum was originally lumped in with Sophora japonica until it was noticed that, although the Pagoda tree is a member of the pea family, and so a legume or nitrogen-fixing plant, some Pagoda tree do not have the ability to work with the rhizobia on their roots that fix nitrogen. So Sophora japonica, as a nitrogen fixer, and Styphnolobium japonicum, a non-nitrogen fixer, have been separated.

The taxonomy of Sophora japonic is listed below:

Pagoda Tree - Sophora japonica

Class - Equisetopsida

Subclass - Magnoliidae

Suborder - Rosanae

Order - Fabales

Family - Fabaceae

Subfamily - Faboideae

Genus - Sophora

Apart from that, both trees are identical, growing to 25m in height apart from the Kew specimen, of course. The leaves are pinnate, with anything from 9 to 21 leaflets, with pendulous flowers.

Apart from being an ornamental plant, it is also popular for use in bonsai. The timber is used for both construction and furniture. The seed pods produce grey and yellow dyes, often used in both the native batik and silk businesses. The leaves and flowers are also edible, although the seeds are poisonous. Medicinally the flower buds are both astringent and as a coagulant.