Ivy-leaved Toadflax, Cymbalaria muralis

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Ivy-leaved Toadflax, Cymbalaria muralis

Ivy-leaved Toadflax, Cymbalaria muralis. Creake Abbey, Norfolk, 5th October 2020.

Ivy-leaved Toadflax, Cymbalaria muralis, is one of my favourite plants.

It brings cheer to old ruins and I admire the way it fills crevices with greenery and pretty Snapdragon-like flowers. We grow it in our garden but I mainly associate it with slightly crumbling old walls. It grows in many places in Norwich and I took the photograph above in early October at Creake Abbey, near Burnham Market in North Norfolk.

Ivy-leaved Toadflax has pretty, spurred flowers. These are produced over a long flowering season, normally from April or May until early October. It is a hardy perennial plant with evergreen, rounded to heart-shaped leaves and a trailing growth habit. Like Common Toadflax, Linaria vulgaris, which I wrote about in September, it is a member of the Plantaginaceae (the Plantain family) (note 1).

It has an unusual method of propagation. Initially Ivy-leaved Toadflax’s flower stalks are positively phototropic, and grow towards the light. But once they have been fertilised they become negatively phototropic, and grow away from the light. Ivy-leaved Toadflax ends up ‘planting’ its own seeds into the dark crevices of rock walls, where they are more likely to germinate. In this way, the plant can colonise walls vertically upwards. It can also reproduce vegetatively, rooting from fragments or from nodes. Richard Mabey describes it as “a delicate but aggressive creeper that trails over walls, banks and pavements” (note 2).

I always use the English name ‘Ivy-leaved Toadflax’ for Cymbalaria muralis, but there are plenty of others to choose from. These include: Kenilworth Ivy, Coliseum Ivy, Kentucky Ivy, Devil’s Ribbon, Oxford Ivy, Oxford Weed, Female Fluellen, Ivy Weed, Ivy Wort, Penny Leaf, Pennywort, Mother of Thousands, Roving Sailor, Wandering Jew, Climbing Sailor and Wandering Sailor (note 3). Cymbalaria means ‘like a cymbal’ and refers to the shape of the flower. The specific name muralis is a Latin adjective and means ‘of walls’.

Cymbalaria muralis is a native of mountainous areas in south and southwest Europe: southern Italy (including Sicily), Switzerland, Slovenia, Croatia, Bosnia and Herzegovina, and Montenegro. It was introduced into the British Isles as a garden plant before 1602, and it was recorded in the wild from 1640 onwards. It may have started out as a rockery plant but it is now very widespread, growing on old walls and bridges, in pavements, and in other well-drained rocky and stony places, often near habitation. It is now our seventh most frequent neophyte (note 4). It has also been introduced into the United States, Australia and New Zealand.

Ivy-leaved Toadflax is listed on the Plants for a Future website, which says that the leaves have been used in salads. On the plus side they are available all year round and they are described as being “acrid and pungent like cress”. But I haven’t been at all tempted to try them because they are “rather bitter and not very pleasant” and “might be toxic“. Externally the plant has been used to make a poultice on fresh wounds to stop  bleeding. There are also reports that it has been used in India to treat diabetes. But I think the best use for the plant is to brighten up old walls.

Ivy-leaved Toadflax makes a good wall, hanging basket or rock garden plant. It prefers a sunny spot but has been growing happily around the base of our north-facing conservatory for the past seven years, though it flowers less here than in full sunshine. I grew my first plant from a fragment of stem, which I rooted in a small vase of water – I find non-flowering stems work best. It is usually difficult to dig up a whole plant from a wall because its roots go deep into crack in a walls and pavements. But you can also buy plug plants and seeds online.

When they aren’t visiting Catmint flowers, Four-banded Flower Bees (Anthophora quadrimaculata) are partial to Ivy-leaved Toadflax flowers and I’ve seen them visiting the flowers in our back garden and elsewhere in Norwich, such as on the churchyard wall outside St. Giles’ Church. But my favourite combination of Ivy-leaved Toadflax and wildlife is in Ventnor Botanic Garden on the Isle of Wight. Here, in the warmer months of the year, Common Wall Lizards (Podarcis muralis) hunt for prey on warm, sunny walls, darting back into the cover of Ivy-leaved Toadlax when disturbed.

Ivy-leaved Toadflax and Wall Lizard

Ivy-leaved Toadflax and Wall Lizard (Podarcis muralis) in Ventnor Botanic Garden, Isle of Wight, 20th May 2016.

Notes

Note 1 – In his Flora, Clive Stace treats Cymbalaria, Linaria, Antirrhinum, Misopates, Veronica (Speedwells), Digitalis (Foxglove) and several other genera as the family Veronicaceae (Speedwell family).

Note 2 – Richard Mabey (1996): “Flora Britannica“, Sinclair-Stevenson, London. Page 331.

Note 3 – There are references for many of the English names on the Germplasm Resource Information Network (GRIN) Global website.

Some of the names come from places where the plant grew. Writing in the 1830s, William Baxter suggested that some Ivy-leaved Toadflax seeds had been accidentally introduced to Oxford with some marble sculptures from Italy. He remarked that the plant had “established itself… on the walls of the Colleges, gardens &c… in abundance” (see note 2 above).  Hence the name ‘Oxford Weed’.

Kenilworth Ivy is presumably named after Kenilworth Castle in Warwickshire and ‘Coliseum Ivy’ because the plant grew on the ruins of the Colosseum in Rome. In France the plant is called ‘ruine de Rome‘.

Other names refer to the plant’s wandering growth habit – Mother of Thousands, Roving Sailor, Wandering Jew, Wandering Sailor – and the ‘Ivy’ and ‘Penny’ names refer to the shape of the leaves.

Note 4 – See p173,  “Alien Plants” by Clive A. Stace and Michael J. Crawley (Harper Collins, 2015). Neophytes are plants introduced to the British Isles after 1492.

Scarlet Caterpillarclub, Cordyceps militaris

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Scarlet Caterpillarclub, Cordyceps militaris

Scarlet Caterpillarclub, Cordyceps militaris.

As a fan of both insects and fungi, I was thrilled to see my very first Scarlet Caterpillarclub fungus, Cordyceps militaris, on a trip to the Norfolk Brecks last Sunday.

I had wanted to see this species for some time and to find not just a single Cordyceps militaris but eleven of them in a single location, in short grass around an oak tree on a grassy heath, was absolutely stunning. The fungus is an infrequent find in the British Isles, and seems to be commoner in the north and west (note 1).

Scarlet Caterpillarclub is a parasitic fungus that grows on the larvae and pupae of moths. The unfortunate host is a caterpillar that has buried into the soil to pupate but is instead consumed by the fungus, which sends up a bright orange club through the turf to spread its spores. When viewed with a hand lens, the bottom of the club (the stipe) is smooth but the upper surface of the club looks bobbly. Cordyceps militaris is an ascomycete fungus and the bobbles are perithecia, small flask-shaped fruiting bodies which contain spores (note 2) .

If you gently extract a Scarlet Caterpillarclub from the soil it is possible to find its unfortunate host. We did this with one of the fungi we found; ours was still a caterpillar but the Lorn Natural History Group website has superb photographs of the fungus growing from both pupae and caterpillars (note 3). The fungus normally grows from the head end of its host.

Cordyceps militaris is the commonest of about a dozen Cordyceps species that have been recorded in the British Isles (note 4) and there are around 400 species worldwide. Cordyceps comes from two Latin words: cord, a club, and ceps, head. Militaris is also from Latin and may refer to the way this fungus attacks, overpowers and occupies its host.

Following DNA sequencing, some species of Cordyceps have now been moved to the genera Ophiocordyceps and Tolypocladium. Several species are so-called “zombie fungi” because of the way they take over an insect’s body and alter its behaviour.

Probably the most (in)famous example is Ophiocordyceps unilateralis, a parasite of carpenter ants, found in tropical forests. The fungus influences the ant’s behaviour, making it travel outside the nest to a more humid place suited to the fungus, removing its instinctive fear of heights and making it climb the stem of a plant, where it clamps its jaws around a leaf vein and waits to die. Fungal hyphae grow out of the ant’s feet to attach it more firmly to the plant and then the fungus digests the ant from within and sends a fruiting body out through the base of the ant’s head, to spread its spores. Some of these spores will infect another ant, to continue the lifecycle. Throughout the process, the fungus is absent from the ant’s brain and the fungus’ influence on the ant appears to be a chemical one, possibly through ergot alkaloids (chemically related to LSD) (note 5).

Ophiocordyceps sinensis, the Chinese Caterpillar Fungus, has a similar lifecycle to our Scarlet Caterpillarclub but is found in Tibet, Bhutan, Nepal, India and China and mainly infects the caterpillars of Thitarodes ghost moths (note 6).

These caterpillars spend their time under the ground, where they feed on roots. They can become infected with fungus spores through their mouth or skin as they move down through the soil. Once infected, a caterpillar moves slowly into a position ideal for spore dispersal (just the right depth for the fungus to push its club above the surface) and its skin changes colour from brown to milky white. Fungal hyphae fill the caterpillar’s body cavity and it is long dead by spring when the fungus sends a stalk up above ground and produces spores to infect the next generation of caterpillars.

The Chinese Caterpillar Fungus has been known about and used in Chinese medicine for generations (note 7). It has been used to treat an assortment of conditions including fatigue, respiratory and kidney diseases and cardiac dysfunction. Research is now being carried out to assess these medicinal properties (note 8).

Ophiocordyceps sinensis suddenly became a lot more popular in 1993 after two unknown female athletes, Wang Junxia and Qu Yunxia, broke records races in China’s National Games in Beijing and their trainer revealed that they had taken Ophiocordyceps sinensis supplements. 

The popularity of Chinese Caterpillar Fungus has had a major impact on the regions where it grows. On the plus side, it has provided much needed income and employment (for whole families) in mountainous areas. But as early as 2005, the New Scientist was reporting “Chinese fungus fad poses eco-threat“. By then the harvest from the Tibetan Plateau and Himalaya Region was around 140,000 kg per annum, with 2,000kg poached from Bhutan alone in 2002, and prices had reached some $7,000 a kilogram, half that of gold. By August 2012, the price had soared to $110,000 per kg in Beijing, almost three times the current price of gold.

Ophiocordyceps sinensis is only found in alpine meadows at altitudes of about 3000–5200 metres (note 9) and its range is retreating upwards as global warming takes hold. Harvesters scour the meadows and use a small pickaxe to remove a patch of grass, together with roots and topsoil, to reveal the fungus emerging from its host. The entire fungus and its attached caterpillar are removed intact, cleaned and sold to itinerant caterpillar fungus traders.

The annual collecting season lasts from about mid-May to mid-July. In this time, collectors can dig up whole meadows, cut alpine shrubs for fuel and dump rubbish, including human faeces which can contaminate water sources. The influx of thousands of people can disturb livestock and wildlife (including the rare Snow Leopard). There have also been some violent disputes over harvesting areas.

Not surprisingly, yields of Ophiocordyceps sinensis appear to be falling (note 10) and the sober conclusion to this tale of overexploitation is: “It now appears increasingly possible that caterpillar fungus, if not properly managed, may be a one-time ecological windfall rather than the inexhaustible resource it once appeared to be.”

Meanwhile, our very own Cordyceps militaris is being investigated too (see Das et. al 2010, for example). Like Ophiocordyceps sinensis, taking extracts of the fungus appears to improve tolerance to high intensity exercise and it may have uses in treating some cancers.

Large-scale artificial cultivation of Ophiocordyceps sinensis in its host is not possible, though small scale production is now taking place. But cultures of Cordyceps / Ophiocordyceps fungi grown without the fungal host – anamorphs (the asexual form of the fungus), grown in liquid cultures or in grain – allow suppliers to produce Cordyceps extracts and powders. The Real Mushrooms website explains more.

It is also possible to grow the sexual stage of Cordyceps militaris in bulk (minus caterpillar). Mushroom Revival, based in Austin in Texas, grow it on a vegan substrate and sell it as a dried fungus or as a tincture. A quick search online gives lots of results for various Cordyceps extracts for sale in the UK too. The Real Mushrooms website says that extracts of this form of the fungus contains the active ingredient cordycepin (3?-deoxyadenosine) in much higher amounts than Cordyceps sinensis.

Some websites say that Scarlet Caterpillarclub isn’t edible but Alan from Minnesota, a chef, offers a recipe on his Forager Chef website: Cordyceps with Linguine, Shallots, Watercress and Chives. He says the ones he bought from San Francisco “weren’t mind blowing, but they definitely weren’t bad“. He wonders whether the fungus tastes the same without its caterpillar – it’s a question of “terroir“.

I don’t plan to try Cordyceps any time soon, but for fans, the RealMushrooms website has links to recipes containing Cordyceps powder, including Sexy Mushroom Truffles and Muscle Recovery Bone Broth.

Cordyceps and Ophiocordyceps fungi have even inspired a video game, The Last of Us, which is set in a post-apocalyptic United States (note 11). In a world of Covid-19 and Trump, that seems a bit too real for comfort, so I’ll stick to going outdoors in the healthy air to look for more fascinating fungi.

Notes

Note 1 – A couple of years ago Norfolk Fungus Study Group found Scarlet Caterpillarclub in the grassland at Felbrigg Hall in North Norfolk, on one of their field trips (which I missed). At time of writing the NBN Atlas doesn’t include this record.

Note 2 – Some club fungi, such as Pipe Club (Typhula fistulosa), are Basidiomycetes.  In contrast to the Scarlet Caterpillarclub, their clubs have a smooth surface.

Note 3 – A variety of species are parasitised but the Lorn Natural History Group website says “The caterpillars are usually well decomposed and hard to identify with certainty”. This was certainly true of our specimen.

Note 4 – (So far) I have only seen the Scarlet Caterpillarclub.

Cordyceps ophioglossoides, the Snaketongue Truffleclub, Cordyceps capitata, the Drunmstick Truffleclub and Cordiceps longisegmentis, are three more British species, but instead of insects they parasitise another fungus, the False Truffle, Elaphomyces granulatus. Their clubs grow from the False Truffle’s underground tubers.

Note 5 – I recommend the book “Entangled Life – How Fungi Make Our Worlds, Change Our Minds and Shape Our Futures” by Merlin Sheldrake, The Bodley Head, London (2020) – Ophiocordyceps unilateralis is discussed in Chapter 4, “Mycelial Minds”.

Jennifer Lu’s National Geographic article “How a parasitic fungus turns ants into ‘zombies'” (April 2019) and its accompanying video are worth a read and watch.

See also “Fungi That Infect Insects: Altering Host Behavior and Beyond” by Shang et.al. (2015).

However, rather than kill their host, some Ophiocordyceps fungi actually help several Japanese species of Cicada to take up nutrients from their diet of plant sap, which is high in sugars, but low in other essential nutrients. See “How To Tame A Zombie Fungus” (Yong, 2018).

Note 6 – A review of Ophiocordyceps sinensis by Wang and Yao in 2011 found 56 potential insect hosts, primarily “ghost moth” larvae of the genus Thitarodes (37 species).

Note 7 – Although its use may go back some 2000 years, the first written references come from a fifteenth-century Tibetan medical text. The first mention in a Chinese medical text is in 1757.

A Chinese name for Ophiocordyceps sinensis is Dong chong xia cao. Like the Tibetan name yartsa gunbu, it means ‘winter worm, summer grass’. The fungus was once thought to transform from an animal to a plant during summer and back to an animal for the winter.

Note 8 – See, for example, Choda 2017 and Belwal 2019 and the RealMushrooms.com website.

Note 9 – Its habitat ecology (including soil types and associated plants) has been studied in Nepal by Sigdel et. al (2017).

Note 10 – For example, official yields in Nepal went from 3.1 kg in 2002 to 2442.4 kg in 2009, before dropping precipitously to just 1170.8 kg in 2011.

Note 11 – Kyle Hill wrote about the game and Cordyceps in the Scientific American blog in 2013: see “The Fungus that Reduced Humanity to The Last of Us“.

Common Toadflax, Linaria vulgaris

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Common Toadflax, Linaria vulgaris

Earlier in the month I wrote about Devil’s-bit Scabious, Succisa pratensis. Another British wild flower that gives a splash of late colour is Common Toadflax, Linaria vulgaris. Here in Norfolk, its yellow flowers light up grassy road verges, it also flowers along grassy rides in Breckland and I grow it in our garden.

Linaria vulgaris is a hardy perennial with stems up to 90cm (36 inches) tall, with narrow, linear bluish-green leaves all round the stem, topped with lovely yellow two-lipped flowers, like a Snapdragon (Antirrhinum majus) but with a long spur at the back. The flowers have a darker yellow or even yellow-orange centre, where the lips meet. (See the Wildflower Finder website for lots of lovely photos.) Common Toadflax can come into flower as early as June and its flowers can usually be found into late October.

Common Toadflax is widely distributed and common in England, Wales and lowland Scotland, but scarcer in Ireland. It grows in open grassy places, on stony and waste ground, in hedge banks, on road verges and railway embankments and on cultivated land, especially on calcareous soils. It is a native of temperate areas of Europe and Asia as far as China, including the British Isles (note 1).

It has been introduced into Japan, North America (Canada and United States), Australia, Chile and South Africa. The CABI Invasive Species Compendium lists countries and states where the plant is found, along with the dates and impacts of introduction (note 2). Where introduced, Linaria vulgaris can be an agricultural weed, especially in Alberta in Canada. It can also compete with native vegetation, as in parts of the United States, including Yellowstone National Park. On the plus side, its roots can help to stabilise soil.

Common Toadflax has creeping roots bearing adventitious buds and over time plants can form dense mats. They can also reproduce by seed (note 3).

Like Ribwort Plantain, Weasel’s-Snout and Sharp-leaved Fluellen, Linaria vulgaris is a member of the Plantaginaceae (the Plantain family) (note 4).

Linaria means “resembling Linum“, because the foliage of some species looks a bit similar to flax (Linum). Vulgaris means “common”. Other English names include Yellow Toadflax and Butter-and-eggs (both from the colour of the flowers).

Common Toadflax makes an ornamental and drought-tolerant garden plant, though its growth habit means you may need to keep an eye on its spread. I grew my plants from seed (from Emorsgate Seeds). Up until recently I grew them in large containers, but I have now planted some in a sunny bed in the front garden. In the past I tried to introduce container grown plants on the allotment but without success. I don’t know why they didn’t thrive – they should like sandy loam.

Linaria vulgaris has a long history of herbal use, listed on the Plants for a Future website. The plant was used as a laxative and diuretic. Extracts were used internally to treat oedema, jaundice, liver diseases, gall bladder complaints and skin problems and externally for haemorrhoids, skin eruptions, sores and malignant ulcers. However, it should only be prescribed by a qualified practitioner and should not be given to pregnant women. A yellow dye is obtained from the plant and a tea made from the plant has been used as an insecticide.

The Wild Flower Finder website lists several of the compounds found in Common Toadflax, including the lignan glycoside liriodendrin and two pyrroloquinazoline alkaloids, peganine and vasicinone.

The “toad” in the English name “Toadflax” may also relate to a medical usage. Apparently  the plants were used to treat bubonic plague and a false link may have been drawn between the words “bubo” (an inflammation of the lymph nodes) and “Bufo“ (a toad).

Common Toadflax flowers have nectar in their flower spurs and this attracts bumblebees. In Britain, only longer-tongued species such as Bombus hortorum (Garden Bumblebee) and Bombus pascuorum (Common Carder Bee) are able to get to this through the flower tube, but shorter-tongued species can overcome the problem by cutting a hole in the side of the spur and robbing the nectar without pollinating the flower.

I usually only see Common Carder Bees on the flowers but other species of bees will visit – the Emorsgate Seeds website features a Wool Carder Bee (Anthidium manicatum) hovering by a Common Toadflax plant (note 5).

Quite a few insects feed on Common Toadflax and the CABI website lists several, though it is mainly interested in them as biological control agents. One species I would like to find is the Toadflax Leaf Beetle, Chrysolina sanguinolenta. It is a rare and local insect but it occurs in Norfolk, especially in the Brecks, so if I keep on searching I may see it one day.

Notes

Note 1 – The BSBI Online Plant Atlas considers it to be a British native but the Wild Flower Finder website says that Common Toadflax may have been introduced to the UK as a garden plant. This is certainly true of its relative, Purple Toadflax, Linaria purpurea, which is native to Italy.

Clive Stace lists eight species of Linaria, plus three hybrids, in his “New Flora of the British Isles“ (Fourth Edition, 2019). Only Linaria vulgaris is native; Linaria repens (Pale Toadflax) is an archaeophyte (an alien which became established before AD 1500) and the others are neophytes (aliens which became established after AD 1500).  (Strictly, the cut off date is 1492, when Christopher Columbus voyaged to the New World.)

There are about 150 species of Linaria worldwide.

Note 2 – Information in this paragraph comes from https://www.cabi.org/isc/datasheet/30828#toDistributionMaps. CABI is the Centre for Agriculture and Bioscience International. Read more about the organisation and its work on its website: https://www.cabi.org.

Note 3 – The CABI fact sheet states that the roots are “widely but wrongly referred to as rhizomes (underground shoot structures)”. Plants “can establish from root fragments as short as 1cm long and the root system may penetrate up to one metre deep and several metres laterally, but shoots mainly originate from the shallower roots at depths of 2 – 5 cm”. Seed production and germination rates are usually low. Up to 100 seeds may form per capsule but viability may be no more than 25%.

Note 4 – Stace treats Linaria, Antirrhinum, Misopates, Veronica (Speedwells), Digitalis (Foxglove) and several other genera as the family Veronicaceae (Speedwell family).

Note 5 – We get Wool Carder Bees on Purple Toadflax (Linaria purpurea) in our garden.