Fairy Foxglove, Erinus alpinus

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Spring is on its way! And one of its many delights is Fairy Foxglove, Erinus alpinus.

Erinus alpinus grows in sunny places in the crevices of old walls and on rock outcrops, often forming large colonies. An individual Fairy Foxglove plant is small and pretty but a mass of Fairy Foxgloves in full flower (usually peaking in May), is beautiful and spectacular.

I still remember my first sighting of Fairy Foxgloves, in late May 2010. Vanna and I were cycling home through the village of Cawston and spotted a mass of pink flowers on an old brick wall near the church. We stopped to admire them and take photographs.

Fairy Foxglove, Erinus alpinus

Fairy Foxglove, Erinus alpinus, on a wall at Cawston, Norfolk. 24th May 2010.

Fairy Foxglove, Erinus alpinus

Closer up: Fairy Foxgloves, Erinus alpinus

Erinus alpinus is a member of the family Plantaginaceae (or Veronicaceae, according to Stace’s Flora (note 1)), a relative of the true Foxglove, Digitalis purpurea, that I wrote about in June 2024.

Foxglove flowers are zygomorphic (they have only one plane of symmetry) but Fairy Foxglove flowers are only slightly zygomorphic (hemi-zygomorphic). The Fairy Foxglove is also much smaller plant, reaching between five and 20 centimetres tall. Foxgloves are biennial; Fairy Foxglove is a short-lived semi-evergreen perennial, usually living for five years or less.

Fairy Foxgloves form clusters of small rosettes of narrowly oblong leaves and ascending leafy stems bearing terminal clusters of flowers. The flowers are usually pink but white forms also occur (note 2).

Erinus alpinus is a neophyte, introduced in 1739 as a garden plant and was known from the wild by 1867 (at Tanfield in North-west Yorkshire). It is very hardy but needs a sunny, well-drained site. It will cope with acid, alkaline or neutral soils but it does need sunshine and good drainage and a rockery would be a good site for it. I grew a Fairy Foxglove plant for a couple of years in an alpine sink in the back garden, where it loved the summer sunshine but ultimately it didn’t cope with shade from the house in winter and I lost it after a couple of years.

Erinus alpinus is native to Algeria, Austria, France, Italy (including Sardinia), Morocco,, Spain (the Balearic Islands) and Switzerland. It grows as an introduced plant in Germany, Great Britain, Ireland and Sweden. (Wikipedia also mentions Algeria.) The plant has several other English names, including Starflower, Alpine Balsam, Jewel Flower and Liver Balsam.

The BSBI Online Plant Atlas 2020 notes that Erinus alpinus has shown “a considerable spread since the 1960s, continuing in the 21st century, perhaps in part a result of the greater propensity of botanists to record plants on garden walls“. Here is the current distribution map:

Distribution map of Erinus alpinus from BSBI Online Plant Atlas 2020.

Distribution map of Erinus alpinus from BSBI Online Plant Atlas 2020.

Fairy Foxglove in Scotland

John Grace wrote an excellent account of Fairy Foxglove on the Botany in Scotland blog in January 2023 and he mentions the furthest north British populations of the plant at Invernaver, near Bettyhill in Sutherland (note 3).

I associate Fairy Foxglove with Scotland, particularly our trip to Oban in 2018. We took the bus to the island Seil, crossing the Clachan Bridge (the Bridge over the Atlantic) to reach the island. The bridge was pink with Fairy Foxgloves and would have made a very fine photograph if we’d been able to stop (note 4).

However, we did manage to see Fairy Foxglove in flower on walls on Oban and, later in the week, when we walked on the beautiful island of Lismore.

Fairy Foxglove, Erinus alpinus

Fairy Foxglove, Erinus alpinus, growing on a wall. Island of Lismore, May 2018.

Erinus alpinus on a wall.

Erinus alpinus growing on a wall in Oban, May 2018.

John Grace also notes Fairy Foxglove’s presence at the village of Wall in Northumberland. This has led to the romanticised view that the plant came on the boots of Roman centurions stationed along Hadrian’s Wall, having been accidentally picked up during their long march across the Pyrenees en route to Britain. But the dates are completely wrong and “like most really good stories this is almost certainly untrue, in fact a sort of Fairy Story“.

The Wild Flower Finder website has some good photos of Erinus alpinus, as does John Grace’s blog post.

Notes

Note 1 – Page 618, “New Flora of the British Isles“ by Clive Stace, Fourth Edition, 2019.

Note 2 – See the Ontario Rock Garden and Hardy Plant Society website for photos of Erinus alpinus with white flowers – and some useful growing tips.

Note 3 – My first Botany field trip when I was a student at aberdeen University was in late June 1982, when we stayed at Bettyhill. We visited Invernaver, though I don’t remember Fairy Foxglove. My flora at the time was the definitely not pocket sized Keble Martin’s Concise British Flora in Colour. I carried it around with me all week and its pages are still marked with where they got wet in a rain shower as I walked downhill from Invernaver Broch.

Note 4 – See https://www.istockphoto.com/photo/clachan-bridge-known-as-bridge-over-the-atlantic-built-in-late-eighteenth-century-gm840599520-136987609 for a stock photo of the bridge, complete with flowering Erinus alpinus.

Dwarf Thistle, Cirsium acaule

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On a cold day in January my thoughts turn to summer flowers. One of my favourites is the Dwarf Thistle, Cirsium acaule.

Dwarf Thistle, Cirsium acaule

Dwarf Thistle, Cirsium acaule

Cirsium acaule is a member of the Daisy family, Asteraceae (formerly known as the Compositae). It is one of nine species of Cirsium growing in the wild in the British Isles (note 1).

Our other species of Cirsium have an upright growth habit. Marsh Thistle (Cirsium palustre) can reach two metres in height, Spear Thistle (Cirsium vulgare) 1.5 metres and Creeping Thistle (Cirsium arvense) 1.2 metres. But the Dwarf Thistle usually just reaches 10 centimetres tall. Because of its short growth form, Cirsium acaule is sometimes known as the Stemless Thistle. (There also is a long-stemmed form, Cirsium acaule var. caulescens, that reaches up to 30 centimetres tall when growing in longer grass.)

Dwarf Thistle, Cirsium acaule

A slightly taller specimen of Dwarf Thistle, Cirsium acaule.

Like its taller relatives, Dwarf Thistle has purple composite flowers. These some 20 to 40 mm across and are produced from June to September. The flowers are followed by masses of fluffy, wind-borne seeds in late summer. Cirsium acaule is a perennial plant and its basal rosette of leaves persists throughout the year, blending in with the surrounding grass. The leaves are deeply lobed and spiny (Stace describes them as “strongly spiny”).

It is easy to sit on a Dwarf Thistle by accident, especially when it isn’t in flower, leading to a painful encounter. The thistles “look just like a nice flat patch of grass to sit on whilst you eat your butties. But automatic ejection is painful and abrupt!” In “Flora Britannica” Richard Mabey writes that Cirsium acaule is “widely known as ‘picnic thistle’ because of its fondness for favourite beauty spots on calcareous grassland and for giving no warning of its lurking spininess even when the flowers are out (note 2).”

Do look carefully at the ground (or take a foam mat to sit on) when picnicking or botanising, just in case.

Dwarf Thistle, Cirsium acaule

Dwarf Thistle, Cirsium acaule

I see Dwarf Thistle most years but I have to travel west because it’s a plant of short chalk grassland and that is scarce in my part of Norfolk (note 3).

The photographs on this blog post were all taken at Warham Camp, an Iron Age hillfort not far from Wells-next-the-Sea in North Norfolk. Here, chalk is at the surface and it’s a good place to see chalk-loving flowers and their associated insects, such as an introduced colony of Chalkhill Blue butterflies (Polyommatus coridon) whose caterpillars feed on Horseshoe Vetch (Hippocrepis comosa). The site is grazed by sheep, which keeps the grass short and rich in flowers, including Dwarf Thistle.

At Warham Camp, the Dwarf Thistles are usually growing amongst grass but this one is on nearly bare ground. You can clearly see the white of the hillfort’s chalk ramparts.

Dwarf Thistle, Cirsium acaule

Dwarf Thistle, Cirsium acaule

Thistle flowers are a rich source of food for insects and I’ve photographed several visitors, such as this Red-tailed Bumblebee (Bombus lapidarius).

Dwarf Thistle and Bombus lapidarius

Dwarf Thistle and Red-tailed Bumblebee (Bombus lapidarius).

Butterflies and moths appreciate the flowers too.

Dwarf Thistle and Essex Skipper

Dwarf Thistle and Essex Skipper butterfly

Dwarf Thistle and Six-spot Burnet

Dwarf Thistle and Six-spot Burnet moth

Cirsium acaule is a British native. It grows as far north as Yorkshire and Derbyshire, with outlying colonies in the Arnside and Silverdale area of north-west England. On the northern edges of its range it is almost wholly confined to south-west-facing slopes. Dwarf Thistle benefits from grazing reducing sward heights to less than 10 –15 cm, or frequent mowing.

Dwarf Thistle’s distribution in the British Isles is determined by the occurrence of short, heavily grazed chalk or limestone grassland, though the plants can occasionally be found on mesotrophic grasslands on deeper soils as well (note 3). Its habitat requirements mean it is absent Scotland, Ireland, most of south-west England and much of Wales (note 4).

Distribution map of Cirsium acaule

Distribution map of Cirsium acaule from BSBI Online Plant Atlas 2020.

Outside the British Isles, Cirsium acaule is native in much of Europe, from Spain, Italy and the north-west Balkans in the south, to Norway and Sweden in the north and Romania and  the Baltic States in the east.

In Britain, Dwarf Thistle has declined since the 1960s, in spite of some new discoveries in Carmarthenshire and Glamorganshire. This is partly because of agricultural “improvement” involving the ploughing-up of grassland or its degradation through the addition of artificial fertilisers. The relaxation of grazing can also harm Cirsium acaule and other plants of short grassland, if tall grasses and scrub take over.

Cirsium acaule is also destroyed by heavy trampling. And, as Eeyore wisely observes: “It don’t do them any Good, you know, sitting on them… Takes all the Life out of them. Remember that another time, all of you. A little Consideration, a little Thought for Others, makes all the difference.” (note 5).

Wise words indeed. The world would be a better place with a little Consideration, a little Thought for Others.

Notes

Note 1 – Clive Stace (2019). “New Flora of the British Isles“.  Fourth Edition.

Stace lists two hybrids between Cirsium acaule and other thistles:

C. x kirschlegeri (C. acaule x C. palustre). This hybrid with Marsh Thistle has shortly spiny-winged stems to 40cm and intermediate leaves and capitula. Found rarely with the parents in southern England but not since 1951.

C. x boulayi (C. acaule x C. arvense). This scarce hybrid with Creeping Thistle has branched stems up to 60cm tall and leaves like C. arvense but with intermediate leaves and capitula.

Note 2 – Richard Mabey (1996). “Flora Britannica”. Sinclair-Stevenson, 1996.

Note 3 – Mesotrophic soils are soils with moderate fertility.

Note 4 – The author of the Wild Flower Finder website, Roger Darlington, wrote that he “has never knowingly seen it in flower, although he may have attempted to sit on a basal rosette of it in his youth whilst walking the hills”. Peter Llewellyn wrote on his UK Wildflowers website: “This is not an uncommon thistle but it prefers basic soils and so until this occasion [5th September 2010] I had never seen it in flower.”

Note 5 – A.A. Milne (1926) “Winnie-the-Pooh“. (From chapter VIII: “In Which Christopher Robin Leads an Expotition to the North Pole”.)

Zythia resinae (aka Sarea resinae)

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It’s always worth looking at tree stumps, as they can host a range of fungi.

This coniferous stump was in a Norfolk wood and is probably the remains of a Douglas Fir, Pseudotsuga menziesii, for they were planted in the wood as a timber crop, amongst the native deciduous trees. The bottom of one side of the stump was covered in a dark patch of resin.

A tall stump of a conifer in a Norfolk wood (May 2025).

The resin was covered in lots of pinky-orange, stalkless cup fungi, each one about a millimetre in diameter.

Conifer resin covered in light orange cup fungi.

I took some photographs and used a knife to remove a small piece of resin with the fungi attached.

Stalkless cups of Zythia resinae on conifer resin.

Back home, I had a look at the cups under the microscope.

The fungi were clearly cup-shaped ascomycetes (sometimes known as discomycetes), with asci (chambers containing spores) and paraphyses (sterile hairlike filaments).

Paraphyses (sterile filamentous hyphal end cells) of Zythia resinae. x1000, stained with Congo red.

I’m used to asci that contain a small number of moderately sized spores (often eight) but these contained a hundred or more tiny spores, each one roughly two micrometres in diameter.

Two asci of Zythia resinae, containing hundreds of tiny spores, each about 2 micrometres in diameter. x1000, stained with Congo red.

I posted my photos on the “Ascomycetes of the World” Facebook page and the genus Zythia/Sarea was suggested. This led me to identify the fungi as Zythia resinae (also known as Sarea resinae).

My find was a “first for Norfolk”, so I dried and froze a sample of fruitbodies and passed them to the Norfolk Fungus Study Group’s DNA team for DNA extraction and sequencing. The results came back in November 2025, confirming my provisional identification. The fungus will be added to the Fungal Records Database of Britain and Ireland under its current name of Zythia resinae but the DNA sequence will be submitted to Genbank as the older Sarea resinae.

I found the fungi on the stump in mid April and revisited at the end of May, when there were many more fruitbodies, in spite of the dry spring.

Zythia resinae

The genus Sarea was thought to contain two species complexes: the black Sarea difformis and the orange Sarea resinae (both sensu lato). But in 2021 Mitchell et. al. examined the morphology and ribosomal DNA (rDNA) of 70 specimens of Sarea and their conclusions supported the split of Sarea difformis s.lat. and Sarea resinae s.lat. into two distinct genera, with Sarea resinae becoming Zythia resinae (note 1).

Zythia resinae is illustrated in Volume 1 of ‘Fungi of Switzerland’ by its older name of Biatorella resinae (on page 240). It features as Sarea resinae in Volume 2 of Laessoe and Petersen’s two volume “Fungi of Temperate Europe” (on page 1461). Other synonyms are Pycnidiella resinae, Cytispora resinae, Cytospora resinae, Sphaeria resinae and Pycnidiella resinae (note 2).

Zythia resinae is known as Sarea resinae on several websites. Jan Thornhill, who is based in central Ontario in Canada, describes her encounter with the fungus on her enjoyable “Weird and Wonderful Wild Mushrooms” blog (‘”Another Fluke: Sarea resinae”, 23rd March 2014). Nearer to home, Chris and Christine Johnson have some excellent photographs on their “Fungi Outer Hebrides” website. There are some good photographs on the AscoFrance Forum and on the Fungi of Great Britain and Ireland website, as well as in the paper “Sareomycetes: more diverse than meets the eye.” (note 1).

Distribution

There are scattered records for Zythia resinae throughout much of the British Isles.

Zythia resinae can also be found in many European countries and also in North America. “Fungi of Temperate Europe” describes it as being widespread and rather common.

This is the current distribution in the British Isles:

Distribution map for Zythia resinae from The British Mycological Society Fungal Records Database of Britain and Ireland. [Accessed on 28th December 2025].

(My record will be submitted to the FRDBI database in 2026, so does not appear on the map above.)

Zythia resinae is small and easily overlooked but lack of a suitable habitat (conifers with patches of resin) probably means it is genuinely scarce in parts of the country with mostly deciduous trees, such as East Anglia. Many woods (especially in Norfolk) are privately owned and lack public access, and this must surely be a factor as well.

The Dark Side

Zythia resinae’s relative, Sarea difformis, also grows on conifer resin. It consists of black discs and was once thought to be a lichen. A black fungus growing on black conifer resin is difficult to see, so it is even easier to overlook than Zythia resinae.

Sarea difformis is illustrated on page 1445 of Volume 2 of Laessoe and Petersen’s two volume “Fungi of Temperate Europe”, where it is described as “widespread, probably common but easily overlooked”. As with Zythia resinae, there are scattered records throughout much of the British Isles, but not from East Anglia.

Its worldwide distribution is similar to that of Zythia resinae, with the addition of a handful of records from Asia.

Gary Walton, who lives in Minnesota in the northern United States, writes about it on his October 2025 blog post “Sarea difformis: A fungus that lives on conifer resin“.

I will keep a lookout for Sarea difformis in Norfolk – now I know that it exists.

Resin eaters?

Zythia resinae and Sarea difformis are known as resinicolous, as they grow on resin from pines and other conifers. They have ancestors that date back to the late Jurassic or Cretaceous periods (about 140 million years ago), around the time that pine trees (genus Pinus) were diversifying (note 1).

Conifers (particularly those in the families Araucariaceae, Pinaceae and Cupressaceae) produce resin in response to damage. This seals wounds, protects against herbivores and inhibits the growth of microbes. Resin is runny when first produced (about the same viscosity as honey) but it soon solidifies. Resin forms a physical barrier to penetration by fungal hyphae, especially when hardened but when it still liquid it can flow around fungal hyphae and spores, trapping them. It also protects chemically, as it contains terpenoids with anti-fungal and anti-bacterial properties. It is a pretty specialised habitat for anything to grow on (note 3).

Zythia resinae‘s specific name resinae comes from the Latin word resina which means “resin” and genus name Zythea is derived from the Greek zythos meaning beer or ale. On the Mushroom Monday substack, Aubrey Carter wonders whether this refers to the idea that the fungus is fermenting some sugar in the resin.

There is still a lot to learn about the physiology and ecology of Zythia resinae and Sarea difformis.

For Zythia resinae, Aubrey Carter says “little is known about how the fungus lives. So little that we’re uncertain where the fungus obtains nutrients — perhaps the mycelium goes inside the tree, perhaps they derive nutrition from the resin itself, or perhaps it’s a different mechanism entirely.”

And for Sarea difformis, Gary Walton says “I have looked for research papers on how Sarea can live on conifer resin, but the results have not yielded much information. Does it actually break down the resin components into simple carbohydrates? If so, then does it do this on its own, or is there a symbiotic relationship with bacteria or another fungus? Are the fungal hyphae growing in the resin or merely on top? How does it disperse? A lot of questions, and I’m sure there are answers somewhere.“

In his 1941 paper “Biatorella Resinae: The Perfect Stage of Zythia Resinae” Theodore Ayers describes how inoculation tests with artificial cultures of Zythia resinae on Pinus strobus failed to show that it was parasitic on the conifer. Since then, many researchers have tried to determine whether whether Sarea and Zythia are parasites, but the conclusions have been contradictory. Mitchell et. al. sum it up: “The varying results and generality of these tests leave unresolved the question of pathogenicity of species in Sareomycetes; some authors assume pathogenicity and others accept a saprobic lifestyle” (note 1).

The conifer stump where I found Zythia resinae was most definitely dead, so presumably the fungi were living saprobically. But the tree must have produced its resin when it was alive and presumably very poorly. When did Zythia resinae colonise the resin? I will never know.

Notes

Note 1 – Mitchell JK, Garrido-Benavent I, Quijada L, Pfister DH (2021). “Sareomycetes: more diverse than meets the eye.” IMA Fungus Vol 12, article 6. The paper is freely available to download at https://link.springer.com/article/10.1186/s43008-021-00056-0. Sarea difformis s.lat. was split into Sarea difformis s.str. and Sarea coeloplata. A new genus was also formed, Atrozythia. Most importantly for us, Sarea resinae s.lat. became Zythia resinae, a single though genetically and morphologically variable species.

Note 2 – These synonyms are listed in the Species Details for Zythia resinae on the British Mycological Society’s Fungal Records Database of Britain and Ireland website. A login is required to access the information, which includes the distribution map shown above, as well as a facility for exploring individual records. New users can register to use the website free at https://www.frdbi.org.uk/user/register.

Note 3 – Resins are solid or highly viscous liquids that can be converted into a polymer. Amber is fossilised tree resin. It sometimes contains insects that were trapped in liquid amber and preserved as it solidified.