Leycesteria formosa – November 29th 2021 Himalayan honeysuckle

This introduced species is expanding its range very rapidly. Before the year 2000 it was quite scarce except in the southern counties of England. Now it has established itself throughout England; in Scotland it has been recorded especially in Edinburgh and Glasgow but it has a strong presence also in the north-east and on the west coast too. Can it be called ‘invasive’? The Natural History Museum defines ‘invasive’ thus:

Invasive species are species outside their normal ranges that have a negative impact on other organisms or environments. They tend to have escaped controlling species (which might be predators, herbivores or parasites) in their normal ranges, which would have otherwise limited their survival, and they are often well suited to their new environment.

I don’t think it can be called ‘invasive’, at least in a British context. It generally occurs as an isolated individual, often growing on the tops of walls and also next to boundary fences, and it doesn’t argue much with other species. It seems to like Scotland, having turned up first in Edinburgh in the 1960s. It is however considered invasive in some countries; in Australia, New Zealand and Micronesia it is ‘a noxious weed’.

What sort of plant is it? It’s a fast growing deciduous shrub, usually reaching about 3 metres in height, and flowering from July onwards before dying back in December. It belongs to the family Caprifoliaceae, the family of honeysuckle and snowberry; in botanical circles it has the English name Himalayan Honeysuckle. In Horticulture they more often call it Flowering nutmeg or Pheasant berry, sometimes Elisha’s tears or Granny’s curls. It has racemes of white to pinkish flowers with maroon bracts, which can be very striking.

Where does it come from? It is a native of China (South-Central), East Himalaya, Myanmar, Nepal, north-eastern India, Pakistan, Tibet, West Himalaya. It lives in these places in wet, rocky woods, forest margins and on cliffs. Its cliff-dwelling tendency helps to explain why we often find it on the tops of walls although perhaps bird dispersal is the real explanation (birds love its berries, see Heleno et al 2010).  Its history in the British Isles is recounted by Coats (1963) and Johnson (2021). The species was introduced to Britain to a garden in Battersea by Nathaniel Wallich in 1824; he was a Danish surgeon and botanist who lived from 1786 to 1854. He travelled to India in 1807 and there he worked as the assistant to William Roxburgh the Scottish surgeon and botanist; Wallich became the Superintendent of the Calcutta Botanical Garden. He collected many species and quite many are named after him. He has Scottish connections: he obtained his medical degree (MD) from Aberdeen University in 1819, and he was elected Fellow of the Royal Society of Edinburgh in 1822. Some of his preserved specimens can be seen at the herbarium of the Royal Botanic Gardens Edinburgh (but I can’t find L. formosa).

Isn’t the botanical name strange?  Leycesteria is nothing to do with the English town of Leicester. Wallich named the new genus in honour of his friend William Leycester a noted amateur horticulturist in Bengal. Formosa is nothing to do with Taiwan (formerly called Formosa), but it comes from the Portuguese word ‘formoso’ meaning ‘handsome’.

Is it poisonous? No toxic effects have been reported. The berries look very tempting but the one I tasted was extremely bitter and left a burning sensation in my mouth and throat. Perhaps pheasants have a different opinion (the name ‘Pheasant Berry’ suggests so). I have read that when ‘fully ripe’ they taste of toffee.

The popularity of the species as a garden plant may have peaked in Victorian times, but several nurseries are now offering clones that have been selected for their colourful bracts.  It does sometimes occur in gardening manuals. Cox and Curtis-Machin (2008) say it is ‘’a weird and exotic looking plant” which “does well in most of Scotland”. Possibly, its recent rapid spread is derived from an upsurge in popularity in gardens – in future I will pay attention to the colours I see in the wild plants and see if I can identify the precise form. I have noticed the red pigments develop especially in bright sunshine, although the plant can thrive in partial shade.

I first met the species in a run-down nursery in South-West Scotland. I was looking for an interesting shrub for my little garden. I saw several handsome arcs of flowers in the distance. I moved in on them, picking my way through thistles and nettles. To my surprise, the plants were growing as weeds in neglected pots of Potentilla fruticosa. The roots had gone through the pot to the soil below. I tugged and almost fell backwards when the roots yielded. The management of this establishment still charged me £5 for my plant even though I pointed out that the Potentilla was completely dead and I wanted only the weed.

References

Coats, Alice M. Garden Shrubs and their Histories pub. Vista Books, Longacre Press Ltd., 161-166 Fleet st., London E.C.4., 1963, entry Leycesteria pps. 195-197.

Cox KNE & Curtis-Machin R (2008) Garden Plants for Scotland. Frances Lincoln, London.

Heleno RH, Ross G, Everard A, Memmott J and Ramos JA (2010) The role of avian ‘seed predators’ as seed dispersers. Ibis 153, 199-203.

Johnson, O. (2021) ‘Leycesteria formosa’ from the website Trees and Shrubs Online (treesandshrubsonline.org/articles/leycesteria/leycesteria-formosa/). 

John Grace