Twinflower, Linnaea borealis

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

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.

Twinflower, Linnaea borealis

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

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

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.

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

Twinflower, Linnaea borealis

Empis tessellata visiting Twinflower flowers.

Twinflower, Linnaea borealis

Empis tessellata visiting Twinflower flowers.

Twinflower, Linnaea borealis

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.

Foxglove, Digitalis purpurea

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We’ve had a magnificent display of Foxgloves this year, after all the rain.

The Foxglove, Digitalis purpurea, is one of my favourite flowers and I can’t help smiling when I see one.

One Foxglove is lovely but a mass of Foxgloves is even better.

Foxgloves, Digitalis purpurea

Foxgloves, Digitalis purpurea, on our allotment. 3rd June 2024.

Digitalis purpurea is a biennial or short-lived perennial herb. It forms a sturdy rosette of leaves in its first year and then a tall flower spike in its second. The plant expends a lot of energy in flowering and often dies straightaway, but sometimes survives to flower less spectacularly the next summer. There is normally only one flower spike per plant but if the flowering stalk is damaged early in its growth, multiple flower spikes can form.

After flowering a Foxglove sets large amounts of seed and the seeds will germinate if there is bare soil and plenty of light, but when the conditions are unsuitable seeds can survive in the soil’s seed bank and produce plants in subsequent years.

Disturbance of the soil and opening up of a tree canopy can trigger a mass germination of Foxglove seeds and Foxgloves can be found in great abundance in disturbed or burnt areas, such as beside tracks and roads or in recently felled forestry plantations.

Digitalis purpurea occurs in nearly every 10km square in the British Isles. Foxgloves like acidic soils, but are a popular garden plant and many of the records in places with alkaline soils are probably garden escapes. The BSBI Plant Atlas lists Foxgloves’ habitats in the British Isles as on hedge banks, in open woods and woodland clearings, on heathland and moorland margins, riverbanks, montane rocky slopes, sea-cliffs, walls and waste land. They can grow quite happily on hillsides with Bracken (Pteridium aquilinum), rising above the fern’s green canopy (note 1).

The name “Foxglove” can be traced back to the Old English “foxes glofa“. The shape of the flower suggests the finger of a glove and, in “Flora Britannica” Richard Mabey suggests the “fox” part of the name comes from the plant’s habit of growing in “foxy places” (note 2). The name “Digitalis” comes from the Latin digitus (finger).

Foxgloves

Foxgloves, Digitalis purpurea, in Oaken Wood, Chiddingfold. 6th June 2018.

When I first studied plants Digitalis purpurea was a member of the family Scrophulariaceae but it was moved to the Veronicaceae in 2001 and nowadays it is considered to be in the Plantaginaceae (note 3).

Worldwide there are about 20 species of Digitalis, all native to Europe, western Asia and north-western Africa.

Digitalis purpurea is native to Belgium, Corsica, the Czech Republic and Slovakia, France, Germany, Great Britain, Ireland, Morocco, Portugal, Sardinia, Spain and Sweden. It has been introduced to many other parts of the world, including large parts of North and South America, several eastern European countries, New Zealand, Tasmania and Zimbabwe. Foxgloves feature in the Invasive Plant Atlas of the United States.

Foxgloves started to flower in mid May this year here in Norfolk but the main flowering period starts in early June. It can continue into September, depending on location. The flowers are a pinky-purple and have spots inside the flower tube. They attract bumblebees, particularly the Garden Bumblebee, Bombus hortorum, Buff-tailed Bumblebee, Bombus terrestris, and the Common Carder Bee, Bombus pascuorum.

Foxglove flowers close up

Foxglove flowers – close up.

White-flowered Foxgloves occur naturally and are often grown in gardens.

The Wild Flower Finder website has pictures of other variations of Foxglove flowers.

White Foxgloves

Also available in white. Foxglove, Digitalis purpurea.

A few weeks ago as I walked past a garden on the other side of our road I noticed a Foxglove with an unusual flower. Most of the flower spike was normal but the top flower was open to the skies and didn’t form the usual tube of fused petals.

This development is known as a terminal peloric flower. Peloric flowers are radially symmetrical flowers that occur in species which normally have flowers with bilateral symmetry.  “Terminal” refers to the flower’s position at the top of the flower spike. “Peloria” is from the Greek word for monster.

The Royal Botanic Gardens Kew website has an interesting article by Paula Rudall, “Weird and Wonderful Foxgloves”, which describes the phenomenon. Breeding experiments have shown that the terminal flower mutation in Digitalis is passed on to the plant’s offspring as a simple Mendelian recessive trait.

Terminal peloric Foxglove flower

Foxglove with a terminal peloric flower.

Terminal peloric Foxglove flower

Close up of the terminal peloric Foxglove flower.

Peloric flowers also can be found in other species which normally have bilateral flowers, such as mints, orchids and Snapdragon (Antirrhinum).

When I a PhD student at the John Innes Centre in the late 1980s, scientists were studying the cause of peloric flowers in Antirrhinum and a resulting scientific paper was published in the journal ‘Nature’ in 1996 as “Origin of Floral Asymmetry in Antirrhinum“.

Foxgloves

Foxgloves, St. Agnes, Isles of Scilly. 20th June 2010.

Foxgloves are poisonous but have a bitter taste so are not tempting to eat. If eaten, vomiting occurs before large amounts of toxins can be absorbed. Symptoms of poisoning include nausea, vomiting (sometimes for more than 24 hours), abdominal pain, diarrhoea, headache and a slow and irregular pulse. Cooking doesn’t destroy the toxins (note 4).

Historically Foxgloves were used as a purgative and the botanist John Parkinson said that they “purge the body both upwards and downwards” (cause diarrhoea and vomiting).

In the late 18th Century the English botanist and physician William Withering used extracts of Foxglove leaves to treat dropsy, an accumulation of fluid in soft tissues caused by a weakness of the heart (note 5). Dosage was critical and too much Foxglove leaf could stop the heart altogether. Withering insisted on using small, accurately measured amounts of dried Foxglove leaf and in his careful research was one of the founders of modern clinical pharmacology.

The active ingredients in Foxgloves are the cardiac glycosides digitoxin and digoxin and they are still widely used in medicine as heart stimulants. They are still extracted from Foxglove plants, but usually from species other than Digitalis purpurea (such as the southern European Digitalis lanata) (note 6).

Notes

Note 1 – The Wild Flower Finder website has a good picture of this.

Note 2 – Where you might find a Fox. Pages 332 – 333 of Richard Mabey’s “Flora Britannica” (Sinclair-Stevenson, 1996).

Note 3 – In Stace’s Flora Digitalis is part of the Veronicaceae. Page 618, “New Flora of the British Isles“ by Clive Stace, Fourth Edition, 2019.

Note 4 – From pages 74 – 75 of “Poisonous Plants and Fungi – An Illustrated Guide” by Marion Cooper and Anthony Johnson, HMSO, 1994.

Note 5 – Nowadays dropsy would be diagnosed as congestive heart failure – the inability of the heart to keep up with the demands on it.

William Withering may have learnt of the cure for dropsy from “an old woman in Shropshire” but the widely quoted story that “Mother Hutton”, a herbalist from Shropshire, sold William Withering the cure for dropsy is a myth invented by a pharmaceutical company for marketing purposes.

Note 6 – During the Second World War native Foxglove leaves were gathered in large quantities for medicinal use, as European plants were unavailable. The harvest was co-ordinated by the County Herb Committees. Careful drying was necessary to preserve the cardiac glycosides.

Beaked Hawk’s-beard, Crepis vesicaria

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Beaked Hawk’s-beard, Crepis vesicaria, is in flower right now, in and around Norwich, its bright yellow flowers livening up grass verges and path edges.

I pass Beaked Hawk’s-beard on grass verges when I walk to the local shops. On Monday we found it by a gravel path on the Yare Valley Walk on the western edge of Norwich. Last week we cycled past a nice patch of it at Taverham when crossed the Norwich’s Northern Distributor Road (NDR) on the Marriott’s Way cycle path.

Beaked Hawksbeard, Crepis vesicaria

Beaked Hawk’s-beard, Crepis vesicaria. Marriott’s Way bridge, Taverham. 9th May 2024.

In the southern half of the British Isles Crepis vesicaria is “the earliest, leafy-stemmed branched dandelion-type to come into flower, very conspicuously, on May roadsides” (note 1). You can find it in flower in the British Isles from May to July.

Considering its abundance in southern Britain, you may be surprised to discover that Beaked Hawk’s-beard is a neophyte, a non-native plant introduced to the British Isles since 1492.

Crepis vesicaria was first recorded in Kent in 1713. It spread rapidly and by 1896 it had reached the west coast of Ireland. It continues to spread and is now well-established in north-east England and spreading in western England, Wales and Ireland. It has a limited distribution in Scotland – so far – perhaps limited by climate.

Crepis vesicaria is a member of the Daisy family, Asteraceae (formerly known as the Compositae) and each flower head is a composite structure consisting of lots of individual small flowers (florets) (note 2).

Beaked Hawk’s-beard is usually a biennial, flowering in its second year, but it does occasionally grow as an annual or perennial. In its first year it produces stalked, deeply lobed basal leaves covered in light down, which persist over winter. In its second year the plant sends up stems clasped by narrow leaves, which branch into multiple flowering stems, each topped with a yellow dandelion-type flower head. The outer ray florets of the flower have an orange-red stripe on the underside (note 3). If cut, the stems bleed bluish-white sap (note 1).

After flowering, Beaked Hawk’s-beard sets seed. Crepis vesicaria seeds have a narrow, elongated “beak” at the top, between the seed and the tuft of silky white hairs (pappus) that serves to distribute the seed in the wind. Hence the name “Beaked Hawk’s-beard” (sometimes spelt “Beaked Hawksbeard”).

There are great photos of Beaked Hawksbeard on the Wild Flower Finder website and Mike Crewe’s Flora of East Anglia has a page of Hawkweeds, Hawk’s-beards & Allies which are useful for comparing Crepis vesicaria with its relatives.

Beaked Hawksbeard, Crepis vesicaria

Beaked Hawk’s-beard, Crepis vesicaria. On a pathside in Norwich, 13th May 2024.

In the British Isles, Beaked Hawk’s-beard mainly grows in disturbed sites: on the verges of paths, tracks and roads, on railway banks, arable margins, set-aside, pavements, gardens, allotments, in waste places and in rough grassland, meadows, lawns and old pits.

Beaked Hawk’s-beard was introduced into Britain from the Mediterranean, probably as a contaminant of grass seed (note 4). It is a native of southern Europe, Turkey, and North Africa (Algeria, Morocco and Tunisia).

As well as the British Isles, Crepis vesicaria has been introduced into the United States (California, Connecticut, Hawaii, New York, North Carolina, Oregon and Pennsylvania), Canada (British Columbia) and Australia (South Australia and Victoria).

The Plants of the World Online website lists nine subspecies of Crepis vesicaria. Most British Beaked Hawk’s-beard plants are Crepis vesicaria subspecies taraxacifolia and have long beaks on all their achenes. But some plants from Cambridgeshire have outer achenes with very short beaks, provisionally making them subsp. stellata (note 5).

In the Norwich area, Beaked Hawk’s-beard is often attended by a solitary bee slightly smaller than a Honeybee, the Cat’s-ear Mining Bee, Andrena humilis.

Andrena humilis is widespread but very localised in southern and central Britain north to Cumbria and Norwich is one of its hotspots. It nests on heathland, coastal grassland, chalk downland and brownfield sites, as well as in large aggregations alongside bare footpaths. The adults forage on dandelions, Cat’s-ear, Mouse-ear Hawkweed and hawk’s-beards. Other bees also visit Beaked Hawk’s-beard flowers, such as species of Furrow Bees (Lasioglossum sp.).

Beaked Hawksbeard, Crepis vesicaria

Beaked Hawk’s-beard, Crepis vesicaria, with visiting Catsear Mining Bee, Andrena humilis.

The Plants For A Future website says that Beaked Hawk’s-beard leaves are edible and can be eaten in a salad but they have a bitter taste. I’m not tempted.

If you want to grow Beaked Hawk’s-beard in your garden it is very easy to grow from seed collected from wild plants. I did this one year but it didn’t establish in our densely planted, north-facing back garden. It should do well in a sunny site with some bare soil – perhaps too well.

Notes

Note 1 – “Harrap’s Wild Flowers: A Field Guide to the Wild Flowers of Britain & Ireland”, page 266. Simon Harrap (Bloomsbury, 2013). Dandelions and Coltsfoot come into flower earlier but their flowerheads are borne on single stems.

Note 2 – I have already written about some of its relatives, including Marsh Sowthistle (August 2023), Common Fleabane (July 2022) and Broad-leaved Ragwort (September 2021).

Note 3 – Beaked Hawk’s-beard close relative, Smooth Hawk’s-beard (Crepis capillaris), also has this stripe and multiple flowerheads but it is a daintier plant that flowers slightly later in the year.

Note 4 – From page 420,  “Alien Plants’” by Clive A. Stace and Michael J. Crawley (Harper Collins, 2015).

Note 5 – Page 756, “New Flora of the British Isles“ by Clive Stace, Fourth Edition, 2019. Stace’s Flora lists ten species of Crepis (Hawk’s-beards) in the British Isles.