One of the highlights of our recent trip to Scotland was Twinflower, Linnaea borealis.

Twinflower, Linnaea borealis, Abernethy National Nature Reserve, June 2024.

Linnaea borealis is a mat-forming creeping perennial herb. In the British Isles it can be found mainly in Northern Scotland, in native pinewoods and plantations of Scots’ Pine (Pinus sylvestris). It occasionally occurs in birchwoods and, rarer still, as a relict of former woodland cover. It grows to 5cm – 15cm (2 – 6 inches) tall and creeps across the woodland floor.

Leaves and flowers of Twinflower, Linnaea borealis, spreading across the woodland floor. 

Twinflower is in the Honeysuckle family (Caprifoliaceae) (note 1).

In Commemoration of Linnaeus

The English name Twinflower refers to the way that the delicate pink flowers of Linnaea borealis come in pairs on a stalk above the foliage (note 2). These are produced from June to August.

Twinflower was Linnaeus‘ favourite flower and the genus Linnaea is named in his honour (note 3).

Finding Twinflower

Twinflower grows in the Eastern Highlands of Scotland but I lacked transport when I was growing up near Aberdeen, so I never saw Twinflower and it remained a mythical plant throughout my childhood and university years.

Years later we went cycle touring in Finland (1998) and Sweden (2000) and saw our first patches of Twinflower.

This year, we visited Scotland in mid June, arriving on the sleeper at Aviemore and travelling to our accomodation in Nethy Bridge by bus.

By coincidence, at the end of May I had read the book “Orchid Summer” by Jon Dunn and remembered his visit to Curr Wood to see Creeping Lady’s-tresses (Goodyera repens), where he saw Twinflower for the first time (note 4).

We were only few miles away from Curr Wood, so we walked up the road to Broomhill, across the A95 and into the wood. After a while we found a patch of Twinflower growing amongst Bilberry and moss. The plants were delicate and beautiful, enhanced by their secluded location amongst Bilberry and mosses under pine trees.

On the way back to Nethy Bridge along the riverside path we chatted with a couple of other naturalists and they told us about another site closer to Nethy Bridge.

We visited this the next day and just after we’d arrived,  Jon Dunn and a friend turned up in a car and came to look at and photograph the plants. It was the first time Jon had seen Twinflower since Curr Wood.

A group of visitors on a guided walk turned up shortly afterwards, so we headed off. We revisited this second site twice more during our stay, on the way back from longer walks, and had the plants to ourselves.

Twinflower, Linnaea borealis. Curr Wood, June 2024

The first impression of Twinflower is of the light pink of the outside of the flower but it’s worth looking at the inside of the flowers because they are a darker pink. This was more obvious in the Curr Wood plants, where the light levels were lower.

Twinflower, Linnaea borealis, showing darker pink inside of flower.

Worldwide Distribution

The name borealis refers to Twinflower’s occurrence in northern boreal forests.

There are three subspecies:

Linnaea borealis ssp. borealis grows in the British Isles and in the temperate zones of Europe and Asia, reaching into Alaska. It has an outlying population high up in the Rwenzori Mountains on the border of Uganda and the Democratic Republic of Congo.

Linnaea borealis var. americana grows mainly in temperate regions of North America.

Linnaea borealis var. longiflora grows in subarctic and subalpine areas from Alaska to northern California.

Fragmented Populations

British Twinflowers are fragmented as a result of loss of habitat into a series of small populations. These are mainly self-incompatible, so the plant’s ability to spread by seed is limited. Most populations are sustained through vegetative reproduction in isolated patches containing one or a few clones.

Thankfully, help is underway and several estates in the Cairngorms National Park are collaborating in a programme to propagate different clones of Twinflower and transplant them into new areas so their flowers can cross-pollinate with existing colonies and set seed.

Some populations of Twinflower do not flower regularly and botanists (such as Brian Ballinger in Easter Ross-shire) have searched for and found several new colonies.

Brian writes on the Botany In Scotland Plant of the Week blog (March 2021): “I would encourage visitors to northern and other pinewoods to keep an eye open for this beautiful plant. It is wintergreen and, once one is familiar with it, Linnaea has a very characteristic growth pattern, so it can be seen in winter when other vegetation may have died back.”

Not the only Visitors

We weren’t the only animals appreciating Twinflower in Curr Wood.

I watched as a Tessellated Dance Fly, Empis tessellata, landed on a flowerhead and spent several minutes with its head buried deeply in the flower, before climbing over to the second flower to repeat the process. Presumbly these flies could be one of Twinflower’s pollinators?

Here are four photos from a much larger sequence:

Twinflower, Linnaea borealis, with Tessellated Dance Fly, Empis tessellata.

Empis tessellata visiting Twinflower flowers.

Empis tessellata visiting Twinflower flowers.

Empis tessellata visiting Twinflower flowers.

Smell The Flowers

I missed one aspect of Twinflower because we were only able to visit plants in daytime.

However, the Scottish Wildlife Trust website tells us that “At night the twinflower emits a fragrance similar to the smells released from the butterfly orchid or lilac”.

This suggests that the plants may be trying to attract moths to pollinate the flowers.

Do sniff the flowers if you’re ever in the right place at the right time, and let me know what you find.

Growing Twinflower

I agree with the Oxford Plants 400 website that “It is always a joy to find this plant [Linnaea borealis] in its natural habitat”.

But if you live in a cooler, wetter part of the country then Linnaea borealis would make a good garden plant and the Royal Horticultural Society website lists three nurseries that sell Twinflower.

The preferred growing conditions are “moderately fertile, humus-rich, reliably moist, acid soil in partial shade“. The plants are very hardy and generally pest and disease free.

It is many years since I visited the delightful Branklyn Garden in Perth but I know from the garden’s Facebook page that Linnaea borealis grows there.

According to the Plants for a Future website Twinflower leaves are edible and the plant has had medicinal uses in the past, but unless you grow it in your garden it’s too rare to harvest, in the British Isles at least.

Notes

Note 1 – I’ve already written about other members of the Caprifoliaceae: Japanese Honeysuckle (October 2023), Devil’s-bit Scabious (September 2020) and Red Valerian (January 2019). Since I wrote about it, the latter has changed name from Centranthus ruber to Valeriana rubra.

Note 2 – We saw a few Twinflower plants with three or even four flowers on the same stalk, instead of two, but these were in a small minority.

Note 3 – Linnaeosicyos, a genus of cucumber from the Dominican Republic, is also named after him.

Note 4 – “Orchid Summer: In Search of the Wildest Flowers of the British Isles” by Jon Dunn (2018), Bloomsbury, London.

Twinflower is mentioned on page 236 and Jon describes the flowering stems: “they are improbably bifurcated, their red stems diverging like French electricity pylons to support two pale pink bell-like flowers”.

We saw Creeping Lady’s-tresses but they were several weeks away from flowering. It would have been good to see them flowering in large quantities.

In Norfolk, they occur in the pine woods at Holkham, but in small numbers. The BSBI Plant Atlas gives three hypotheses for the origin of the East Anglian plants: transplanting from Scotland alongside Scots’ Pine seedlings, subsequent natural colonisation of the pine plantations by wind-blown seed, or (less likely) preceding the pine plantations as natural populations that initially occupied open heathland.