Tuesday, 29 July 2014

A Sweet Smelling Champion in our Midst

A champion amongst us
A plant which is worth giving a second glance to at the moment is Clerodendrum trichotomum var. fargesii, which is in the Lamiaceae, or mint family. It comes from China and Japan and arrived at the garden in 1989. Since then it has grown massively - it is classified as one of the Champion Trees on the Tree Register, because it is the largest known example in Britain. It is planted in the Fern Border in the North East corner of the Walled Garden.

It is a beautiful tree, with a branching, three tiered structural habit. It is flowering at the moment, filling the garden with a delicious aroma of jasmine-crossed-with-lemon blossoms. The flowers themselves are tiny and borne in clusters around the richly green, ovate leaves. Each flower consists of a long tube which divides out into five, almost star-like petals arising from a pink blushed, pale green calyx made up of five sepals. 
A honey bee visits a flower leaving behind a parcel of pollen
The flowers are pollinated by insects who take advantage of a nectar reward in exchange for carrying pollen from one flower to another. Freshly opened flowers are creamy white with four stamens, each carrying an upward reaching brown anther, and a single style pointing down towards the ground. As the flowers mature, the petals darken to a yellowish cream and the stamens turn backwards, and point down, while the style lifts up, ready to accept pollen from an insect. This is a clever way for the plant to avoid self-fertilisation, which results in poor genetic variation, and weaker offspring. In the autumn the flowers are replaced by turquoise fruit surrounded by sepals which turn a vivid pink, making this plant a point of interest later on in the year too.

In autumn 2013 a team from Oxford Botanic Garden and Harcourt Arboretum travelled to Japan on a seed collection trip. One of the plants collected was Clerodendrum trichotomum. To find out more about the Japan project take a look at our previous posts.

Autumn fruits of Clerodendrum trichotomum in the wild 

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