Bastard-toadflax, Thesium humifusum

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A less-known relative of Mistletoe

Back in 2015 I wrote about Mistletoe, Viscum album. It’s a well known plant associated with midwinter celebrations and the subject of stories and folklore. But it has a much lesser known, smaller cousin that grows in the British Isles, Bastard-toadflax, Thesium humifusum.

Mistletoe and Bastard-toadflax are the two members of the Santalaceae, the Sandalwood family, found in the British Isles.

Mistletoe grows on our allotment site but Bastard-toadflax prefers heavily grazed calcareous grassland so is an hour-and-a-half’s train ride away, near Royston in Hertfordshire. Last week Vanna and I went to see it.

We walked across the golf course, encountering Marbled White, Chalkhill Blue and Dark-green Fritillary butterflies, to the chalk hillside where we sometimes go in spring to see Pasque Flowers, Pulsatilla vulgaris. Last time we visited Vanna had found an interesting shieldbug and she subsequently identified it as a Down Shieldbug, Canthophorus impressus, which feeds on Bastard-toadflax (note 1).

We decided to go back and look for the Down Shieldbug’s foodplant.

Down Shieldbug, Canthophorus impressus

Down Shieldbug, Canthophorus impressus. Both adults and the black and red nymphs feed on Bastard-toadflax. (July 2026.)

Searching for Bastard-toadflax

You need to know what to look for when searching for Bastard-toadflax.

Bastard-toadflax is a small and low growing perennial plant. It has strap-shaped leaves with a  leaves of a similar shape (long and thin) to true toadflaxes, members of the Plantaginaceae, the plantain family (note 2). But its flowers are very different: Bastard-toadflax doesn’t have the spurred flowers of true toadflaxes.

After a bit of searching but I eventually found some Bastard-toadflax at Royston and, once we’d noticed that its yellow-green leaves stood out from other vegetation we were able to spot other patches of the plant as it sprawled across the ground amongst other short vegetation. Vanna also found another Down Shieldbug.

Thesium humifusum could never be described as spectacular but it is very attractive nonetheless, with flowers with their white tepals, shaped like stars, fitting the plant’s alternative English name of “Stars in the Grass” (note 3).

Bastard-toadflax, Thesium humifusum

Sprawling across the ground: Bastard-toadflax, Thesium humifusum.

Bastard-toadflax, Thesium humifusum

Closer up: Bastard-toadflax, Thesium humifusum.

Bastard-toadflax, Thesium humifusum

Closer still: The attractive white flowers of Bastard-toadflax, Thesium humifusum.

All members of the Santalaceae are hemi-parasites. They have green leaves and manufactures their own sugars by photosynthesis but absorb nutrients and water from their host via a specialised structure called a haustorium (plural haustoria).

The family includes the White or Indian Sandalwood tree, Santalum album, which a native of Indonesia, the Philippines and Western Australia, used as a source of timber for woodworking (until most of the larger trees were cut down) and for sandalwood oil. Although it grows as a small tree its flowers and leaves  (illustrated on Wikipedia) remind me of Mistletoe and Bastard-toadflax.

Thesium humifusum is hemi-parasitic on the roots of various herbs, including Hedge Bedstraw (Galium album) and Lady’s Bedstraw (Galium verum) (note 4). it is a perennial herb, with prostrate herbaceous shoots that grow from a woody rootstock.

Distribution

In the British Isles, Bastard-toadflax is found in short, usually heavily grazed, species-rich calcareous grassland, chiefly on chalk, less frequently on limestone, and rarely on clays or calcareous sandy soils near the coast. It is found in the Channel Islands and in mainland England but is absent from Scotland, Ireland and Wales.

It has been lost from many former sites. In Somerset in the nineteenth century it was found at Claverton Down and Hampton Down near Bath, but these sites are now occupied by the University of Bath and Bath Golf Club. Other losses occurred when downland was ploughed or treated with fertiliser or when scrub encroached on grassland. The plant is now absent in many grid squares where it occurred before 1930 and even nowadays there is still an ongoing decline.

Distribution map for Bastard-toadflax, Thesium humifusum

Distribution map for Bastard-toadflax, Thesium humifusum, from BSBI Online Plant Atlas 2020.

Outside the British Isles, Thesium humifusum occurs in Belgium, France, the Netherlands and Spain. It is very scarce in the Netherlands and confined to one or two sand dunes.

More Pictures

If you want to find your own Bastard-toadflax there are some good photographs of the plant on the Wild Flower Finder website. Mike Crewe’s Flora of East Anglia also features the plant and the UK Wildflowers website has photos of the plant on the Devil’s Dyke near Newmarket.

Bastard-toadflax was the Sussex Biodiversity Record Centre’s species of the month in August 2019.

Finally, a couple more of my photographs from near Royston:

Bastard-toadflax, Thesium humifusum

Bastard-toadflax, Thesium humifusum.

Bastard-toadflax, Thesium humifusum

Bastard-toadflax, Thesium humifusum.

Notes

Note 1 – According to Richard Jones (“Shieldbugs”, William Collins, 2023) Down Shieldbug, Canthophorus impressus, feeds on Bastard-toadflax (Thesium humifusum) in the British Isles and its relative Thesium alpinum in mountains of Europe.

Thesium alpinum is now considered to be a synonym of Thesium bavarum.  (Miguel A. García, Ladislav Mucina & Daniel L. Nickrent (2023) “A tough nutlet to crack: resolving the phylogeny of Thesium (Thesiaceae), the largest genus in Santalales.“)

Canthophorus impressus is also known as the Bastard-toadflax Bug.

See “Bastard Toadflax bug at Hartslock“. Hartslock Nature Reserve is located on the north side of the Thames between Whitchurch and Goring-on-Thames, Oxfordshire. The site is owned by The Wildlife Trust for Berks, Bucks & Oxon (BBOWT).

If you find a powdery mildew on Thesium humifusum it will be Erysiphe thesii. So far it has only been recorded from Hartslock.

Note 2 – But not all toadflaxes. The leaves are thin like those of Common Toadflax, Linaria vulgaris but very different from those of Ivy-leaved Toadflax, Cymbalaria muralis.

Note 3 – The English name is sometimes spelt without the hyphen (“Bastard Toadflax”).

Note 4 – Wikipedia says “Thesium humifusum is a hemiparasitic plant that steals nutrients from hedge bedstraw (Galium album) or lady’s bedstraw (Galium verum).” The reference is from the FLORON Distribution Atlas Vascular Plants (of the Netherlands). Both species were growing where we found our Bastard-toadflax plants.

Sea Bindweed, Calystegia soldanella

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On holiday in Cumbria last week, we visited the magnificent sand dunes at Sandscale Haws. We didn’t see any of the Sea-kale, Crambe maritima, I wrote about in April but there were lots of other lovely plants, including masses of Burnet Rose, Rosa spinosissima, at the back of the dunes, Sea Rocket, Cakile maritima, on the beach and dune slacks full of orchids.

One of the highlights of our visit was a big patch of Sea Bindweed, Calystegia soldanella. It was growing on a south facing slope a little way in from the edge of the dunes.

Sea Bindweed, Calystegia soldanella, in the dunes at Sandscale Haws in Cumbria (17th June 2026).

Where the Sea Bindweed grows

Sea Bindweed, Calystegia soldanella, is one of the delights of Britain’s coasts and one of my favourite plants. It has beautiful striped flowers, pink decorated with five narrower white bands. Its leaves are elegant, shiny and kidney-shaped and its stems sprawl over the ground.

Sea Bindweed often grows in scenic places too. As I write (with curtains closed to keep the sun out) we are experiencing record-breaking  June temperatures (38 degrees Celsius at the moment) but just looking at a photograph Sea Bindweed on a beach in the Isles of Scilly is making me feel much better.

Sea Bindweed, Calystegia soldanella, on a beach on St. Agnes, Isles of Scilly (June 2010).

Sea Bindweed is a member of the Convolvulaceae (Bindweed family). The family includes the edible Sweet Potato, Ipomoea batatas, and the parasitic Dodder, Cuscuta epithymum, that I wrote about in July 2021.

Bindweeds, especially other species of Calystegia such as Hedge Bindweed (Calystegia sepium) and Large Bindweed (Calysegia silvatica), grow very rampantly and are hated by many gardeners because of their persistent roots and invasive growth habits (note 1). Field Bindweed, Convolvulus arvensis, is another close relative and can also be persistent weed . All three species have very attractive flowers and those of Field Bindweed are delightfully perfumed and well worth a sniff! (note 2). [See “Relatives of Sea Bindweed” below for pictures of Field and Large Bindweed.]

Sea Bindweed, Calystegia soldanella, is their more refined coastal cousin. It too has long roots and these can grow more than 70 cm under sand cover (note 3) but it prefers growing on sand dunes and above the strand-line on sand and shingle beaches, so is unlikely to be encountered as a “weed”. It is a trailing perennial herb, rather than a vigorous climber, and it gently grows across sand or amongst other vegetation. Its flowers are beautiful, and typical of our other species of Calystegia) tin having no noticeable scent.

Sea Bindweed is restricted to coastal sites in the British isles, though it is hardy to -10 to -15 degrees Celsius (hardiness rating H5). It needs to be tough to cope with salt, hot sunshine and drought conditions.

On Sea Bindweed’s current status, the 2020 BSBI Plant Atlas says: “The loss of sand dunes and increased recreational disturbance on those that remain have resulted in many losses of this species during the 20th century, particularly in southern and eastern England, although it seems to be relatively resistant to trampling. Its distribution since the 1990s appears to be stable, save for coastal areas in eastern Scotland, where there are very few recent records.”

Distribution map of Calystegia soldanella from BSBI Online Plant Atlas 2020.

Calystegia soldanella is a native of the British Isles. It is scarce in Northern Scotland, although it can be found on Orkney. It is included in rare plant registers for several Vice-Counties.

It is a native coastal plant in many other temperate and sub-tropical parts of the world. The Plants of the World Online website gives the native range for Sea Bindweed as follows: Europe (but not Scandinavia), North Africa, the Middle East and Iran, the United States (western states but also Virginia), parts of South America, South Africa, Australia and New Zealand.

The New Zealand Plant Conservation Network gives an account of the plant in New Zealand.

The BSBI website says it is “widely naturalized outside its native range” but Plants of the World Online doesn’t mention this.

The Royal Horticultural Society (RHS) website suggests growing Calystegia soldanella in a gravel or coastal garden, in sunny conditions with very sharp drainage. It is “unlikely to become a garden weed“. It suggests that slugs and snails may be attracted to the plant. The EarthOne website has more growing tips. I don’t intend to try but I wonder whether Sea Bindweed would grow in the sandy soil on my allotment?

Sea Bindweed in pictures

Time for some more pictures.

The first one shows a flower bud just above two open flowers:

Sea Bindweed, Calystegia soldanella. Flower bud at top of photograph, above the flowers.

Plants flower from June to September, with a peak in June to July. After flowering, Sea Bindweed forms its seeds.

The seeds are comparatively heavy and tend to remain on the sand surface, where they can remain until winter storms wash them out to sea. When they looked at soil core samples the authors of a study in Tuscany (Italy), failed to find any seeds and concluded that the local spread of Sea Bindweed was by its extensive root system, leading to large clonal patches of plants (note 3).

For long distance dispersal, Sea Bindweed seeds are able to float for a long time with maintaining viability and up to 90% of the seeds can germinate after nine months of immersion in sea water. This may help to explain the plant’s global distribution.

Populations of Calystegia soldanella in Europe show a low level of genetic divergence, as do Korean populations. This lends support to the hypothesis that seeds can be spread for long distances by sea (note 4).

Sea Bindweed, Calystegia soldanella. Leaves and a seed pod. Holkham Dunes, Norfolk (July 2022).

Even when not in flower, Sea Bindweed’s shiny, kidney-shaped leaves are very distinctive.

Sea Bindweed and wildlife

Sea Bindweed flowers are insect pollinated.

The Native Wildflowers website says they are “mainly pollinated by hawkmoths.” I’ve never observed this but I don’t hang around in sand dunes at night.

The Plants for a Future website mentions pollination by bees and moths and butterflies.

I have a couple of photographs of bees visiting the flowers: a species of furrow bee (Lasioglossum or Halictus sp.) on a beach on St. Agnes in the Isles of Scilly in 2010 and, from last week, a species of bumblebee (Bombus sp.) at Sandscale Haws.

Sea Bindweed, Calystegia soldanella, with visiting furrow bee (Lasioglossum or Halictus sp.). St. Agnes, Isles of Scilly (June 2010).

Sea Bindweed, Calystegia soldanella, with visiting bumblebee at Sandscale Haws (June 2026).

Plant Associations

The BSBI Plant Atlas notes that Sea Bindweed often grows with Sea Holly, Eryngium maritimum – as in this photograph from Sandscale Haws:

Sea Bindweed, Calystegia soldanella, with Sea Holly, Eryngium maritimum. Sandscale Haws, Cumbria (June 2026).

On a visit to Winterton Dunes, Norfolk Flora Group found Sea Bindweed scrambling amongst the abundant Marram Grass Ammophila arenaria.

At Sandscale Haws, Sea Bindweed was also growing with Common Restharrow, Ononis repens. Both plants had pink flowers but the flower shapes and shades of pink made a pleasing contrast.

Sea Bindweed, Calystegia soldanella, with Common Restharrow, Ononis repens. In the dunes at Sandscale Haws in Cumbria (June 2026).

Other names for Calystegia soldanella

Other English names for Calystegia soldanella include: Scotch Scurvy Grass, Sea Bells, Seashore False Bindweed, Shore Bindweed, Shore Convolvulus and Beach Morning Glory.

A more romantic name is “The Prince’s Flower”.  On 23 July 1745, Bonnie Prince Charlie (Charles Edward Stuart) landed on the island of Eriskay in the Outer Hebrides, with seven companions (known as the the Seven Men of Moidart). The beach where he landed is now known as Coilleag a’ Phrionnsa (“The Prince’s Strand).

The story goes that seeds of Sea Bindweed fell out of his pocket when he took out his handkerchief and the plant took root.

Whether or not this is true, Sea Bindweed still grows on that beach today.

Sea Bindweed as food

Sea Bindweed has been used for food.

In New Zealand “Maori gathered the thick, white, fleshy roots and pounded these to form a pulp, this was then used as a relish to flavour some meats.”

The Plants for a Future website says that young shoots can be cooked as a vegetable or pickled and used as a samphire substitute. However, it advises caution because the plant “might have a purgative effect”.

The Plants for a Future website also lists some possible medical uses for the plant.

I think I’ll stick to admiring its flowers.

Further Reading

See the Botany In Scotland blog for an interesting description of Calystegia soldanella and this and the Wild Flower Finder website for more photographs.

Mike Crewe’s Flora of East Anglia website has a useful page comparing different bindweeds.

Relatives of Sea Bindweed

Large Bindweed, Calystegia silvatica

Large Bindweed, Calystegia silvatica, has short, wide bracteoles which overlap where they meet, hiding the sepals. On our allotment site (June 2025). The sepals are visible in its close relative, Hedge Bindweed, Calystegia sepium.

Field Bindweed, Convolvulus arvensis

Field Bindweed, Convolvulus arvensis. On a road verge in Suffolk (June 2025). Although this plant was low and spreading, the flowers and leaves were very different to those of Sea Bindweed. (The leaf just left of centre belongs to a Common Mallow plant.)

Notes

Note 1 – When they are in flower you can tell apart Hedge Bindweed (Calystegia sepium) and Large Bindweed (Calysegia silvatica) by looking at their bracteoles, the green leaf-like stuctures at the base of the flower. Large Bindweed has short, wider bracteoles which overlap where they meet. Hedge Bindweed has narrower, longer bracteoles with a gap between them, allowing a glimpse of the sepals.

Note 2 – We have lots of Field Bindweed, Convolvulus arvensis, on our allotment. I tolerate it at the edges of the plot but remove shoots that emerge in vegetable beds. Most of the roots are unharmed when I do this but I prevent the plant from outcompeting or enveloping other plants.

When we took on our allotments over 25 years ago we double dug each plot to remove roots of perennial weeds and found Field Bindweed roots in the subsoil more than two spade depths down. Since then, our aim has been to control the plant rather than eliminate it.

I didn’t realise Field Bindweed had scented flowers until about ten years ago when Vanna invited me to sniff some when we were at Warham Camp in North Norfolk. I had sniffed Large Bindweed flowers as a child and had assumed that Field Bindweed had no scent either, but I was wrong.

Note 3 – Di Sacco A and Bedini G (2015). Demography and reproductive performance of Calystegia soldanella on a sandy seashore in Tuscany, Italy. Botany Vol. 93, pp100-108.

Note 4 – R. Arafeh,”Molecular phylogeography of the European coastal plants Crithmum maritimum L., Halimione portulacoides (L.) Aellen, Salsola kali L. and Calystegia soldanella (L.) R. Br.” The paper has information about seed viability after immersion in sea water and its long roots are shown in figure 2.

Heath Navel, Lichenomphalia ericetorum

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On Sunday three three of us visited Holt Lowes in North Norfolk. It was very dry and fungi were rather scarce, so we spent most of the time looking at plants. But on a low peaty bank at the edge of the valley mire we found some small, slightly dried out fungal fruitbodies and I brought a couple home to identify.

Lichenomphalia ericetorum

Heath Navel, Lichenomphalia ericetorum. Holt Lowes, Norfolk, 17th May 2026. (The Bracken stem at the top of the photograph is infected with the extremely common Bracken Map fungus, Rhopographus filicinus.)

Lichenomphalia ericetorum

I looked in Volume 2 of Geoffrey Kibby’s “Mushrooms and Toadstools of Britain and Europe” for a possible match and found Lichenomphalia umbellifera.

The species is known as Lichenomphalia ericetorum in The Fungal Database of Britain and Ireland (FRDBI). (Other synonums include Omphalina ericetorum and Botrydina vulgaris.) The species was first described by Linnaeus in 1753 as Agaricus umbelliferus.

The fungus had white spores and decurrent gills. These were widely spaced and sometimes forked and formed veins linking adjacent gills.. When fresh the gills are pale yellowish but in my samples they had dried a darker yellow-orange.  The stipe attached to the centre of the cap and was reddish-brown at the tip. (This colour continued into the lower part of the gills in my specimens.) The base of the stipe was slightly enlarged and covered with a pale fuzz.

Lichenomphalia ericetorum

Lichenomphalia ericetorum – two picked fruitbodies.

Lichenomphalia ericetorum spores look like this:

Spores of Lichenomphalia ericetorum.

Spores of Lichenomphalia ericetorum (x1000, in Meltzer’s reagent, which colours them yellow).

So far, so normal.

But I found a 2023 blog post by Sim Elliott and the story became much more interesting.

Lichenomphalia ericetorum: Not Just a Fungus, but a Basidiolichen

At first glance, Lichenomphalia ericetorum appears to be a normal basidiomycete fungus but the fruitbody is actually part of a lichen, an association between a fungus and an alga (note 1).

Lichen fungi have evolved independently several times.

Most fungi found in lichens (98%) are ascomycetes (sac or cup fungi) and these give most of the familiar and easily recognised growth forms: a thallus consisting of a colourful crust, a rosette or a leafy (foliose) or shrubby (fruticose) structure.

A much smaller number of lichens have a basidiomycete fungus as the fungal partner. What we see in Lichenomphalia ericetorum is the fungal fruitbody of one of these basidiolichens.

If you look closely at the base of the Lichenomphalia ericetorum you will see a mass of green blobs. These are green algae in the genus Coccomyxa and are the photosynthetic partner (the photobiont).

The green blobs at the base of the stem are a green alga (Coccomyxa sp.).

The green blobs at the base of the stem are a green alga (Coccomyxa sp.). They are the photosynthetic partner in the lichen (the photobiont).

Seen under the microscope:

Coccomyxa sp. algae under the microscope.

Coccomyxa sp. algae under the microscope (x100).

Two alternative English names for Lichenomphalia ericetorum, Lichen Agaric and Pea-green Mushroom Lichen, describe its true status as a basidiolichen.

Distribution of Lichenomphalia ericetorum

In Norfolk Lichenomphalia ericetorum had been recorded 30 times from 24 different sites up to the end of 2025.

In the British Isles as a whole there are currently 492 records of Lichenomphalia ericetorum, with a northern bias.

Distribution map for Lichenomphalia ericetorum (FRDBI)

Distribution map for Lichenomphalia ericetorum from The British Mycological Society Fungal Records Database of Britain and Ireland. [Accessed on 17th May 2026]

The British Lichen Society website also has a map of the distribution of Lichenomphalia ericetorum but at the time of writing this has no records for Norfolk. (Norfolk records are also missing from my copy of “Lichens” by Frank Dobson (note 2).)

Outside the British Isles, Lichenomphalia ericetorumis found in the northern hemisphere, particularly in the region of the Arctic. It is common in the  Pacific Northwest of Canada and the United States, northward from Santa Cruz in California.

Lichenomphalia ericetorum in Scotland

I remembered seeing some similar fungi a couple of years ago, when Vanna and I were walking the Ryvoan Pass in the Scottish Highlands (note 3).

I found the photos. The Scottish examples were in much better condition than the ones from Norfolk.

At first glance the fungi seemed to be growing in mosses:

Lichenomphalia ericetorum

Heath Navel, Lichenomphalia ericetorum. Abernethy Forest, 24th June 2024.

But when I looked closely at a second photo it was possible to see the green blobs of Coccomyxa algae more clearly. I’ve cropped the photo to make these easier to see:

Lichenomphalia ericetorum

Heath Navel, Lichenomphalia ericetorum. Abernethy Forest, 24th June 2024. Here it’s possible to see the green blobs of Coccomyxa algae at the bottom right of the photograph.

I recommend a read of Sim Elliott’s “A lichen that fruits like a mushroom. Lichenomphalia umbellifera at Eridge Rocks. 30.07.23“, which has some good photographs too (from Sussex). The pictures of Lichenomphalia ericetorum on the Lichens Maritimes website (from France and Belgium) are worth a look too.

Notes

Note 1 – Lichens are made up of two or more closely interacting organisms, a fungus, and one or more photosynthetic partners (photobionts).

The lichen symbiosis is thought to be a mutualistic relationship, in which both the fungus and its photobionts benefit. The fungus forms the main structure of the lichen (known as the thallus), which provides a home for the photobionts. These produce simple sugars by photosynthesis, which are used as food by the fungi.

90% of lichen photobionts are green algae and the remainder are cyanobacteria.

98% of lichen fungi are ascomycetes (sac or cup fungi). It is thought that one fifth of all known fungi and half of all ascomycetes are lichenised, with about 28,000 species worldwide.

Note 2 – “Lichens: An Illustrated Guide to the British and Irish Species” by Frank S. Dobson. 7th edition (2018, reprinted 2023). The British Lichen Society, London.

Note 3 – The Ryvoan Pass is a lovely 10 mile walk from Glenmore Lodge to Nethy Bridge in the Scottish Highlands. We were staying in a holiday cottage in Nethy Bridge in June 2024 and took a bus to Aviemore and another to Glenmore Lodge. We had bought return tickets but it was such a lovely summer day that we decided to walk the whole route back to Nethy Bridge.

We passed the beautiful An Lochan Uaine (green lochan), headed uphill to the Ryvoan Bothy and through Abernethy Forest. Here we saw Bog Beacon and Twinflower but – sadly or fortunately – didn’t encounter any rogue Capercaillies.

Warning sign: Rogue Capercaillie

Warning sign: Rogue Capercaillie.

An Lochan Uaine

An Lochan Uaine (green lochan), passed on the Pass of Ryvoan walk. The lovely green colour of the water is allegedly caused by fairies washing their clothes at night.