Broad-leaved Ragwort, Senecio sarracenicus

Jeremy Bartlett's LET IT GROW blog Posted on by
Broad-leaved Ragwort, Senecio sarracenicus

Broad-leaved Ragwort, Senecio sarracenicus at Wheatfen. Growing along the edges of the wood, where it looked as if it was part of a wild herbaceous border.

I’m lucky to live close to some very special places, one of which is Wheatfen Nature Reserve, on the south bank of the River Yare just east of Norwich. I visited a couple of weeks ago to look at plants and late summer insects, and walked through Home Marsh, a part of the reserve I haven’t visited before at this time of year.

I found a new species (for me), which I had to look up in my books when I came home: Broad-leaved Ragwort, Senecio sarracenicus. It is a statuesque plant, clearly a type of Ragwort, with the typical yellow daisy flowers, but with broad leaves, green on both the upper and lower sides. It was growing in large clumps in the marsh and along the edges of the wood, where it looked as if it was part of a wild herbaceous border.

Broad-leaved Ragwort, Senecio sarracenicus, is a hardy perennial that grows to 1.5 or even two metres tall in damp places and is in flower from July to September (and possibly earlier in some places: the Wildflower Finder website says it flowers from May to July). It is a member of the Asteraceae (formerly Compositae, the Daisy family) and a close relative of the superb wildlife plant our native Common Ragwort (Jacobaea vulgaris).

In the British Isles, Senecio sarracenicus is a neophyte and was introduced in 1632 (note 1). It is a native of other parts of Europe, to Siberia and Turkey. The NBN Atlas website has a map of British records, though this misses out the known sites in Norfolk: Wheatfen, Hoveton and Martham (note 2). Most records are from Scotland and the north of England.

The Wild Flower Finder, UK Wildflowers and Nature Gate websites have some good photographs of Broad-leaved Ragwort, which was formerly known as Senecio fluviatilis. Its older English names include Saracen’s Woundwort, Saracen’s Comfrey and Saracen’s Consound.

So why is Broad-leaved Ragwort growing at Wheatfen?

I found the answer in a booklet I’d bought on a previous trip to the reserve (note 3).

For forty years Wheatfen was the home of by Ted Ellis (1909-1986), the naturalist, writer and broadcaster (note 4).

In the 1930s Ted tried to reintroduce the Large Copper butterfly to Wheatfen. The butterfly used to occur in fens in East Anglia and Lincolnshire and was “once widespread” at Wheatfen. He planted Broad-leaved Ragwort to provide late summer nectar for the Large Coppers.

The Large Copper’s foodplant is Water Dock (Rumex hydrolapathum), which is abundant on the reserve but the project failed, as did the more well known reintroduction at Woodwalton Fen (note 5).

The plant lives on and is thriving, long after the Large Coppers – and Ted Ellis – have gone.

Broad-leaved Ragwort ,Senecio sarracenicus

Broad-leaved Ragwort, Senecio sarracenicus

Notes

Note 1 – From p72,  ‘Alien Plants’ by Clive A. Stace and Michael J. Crawley (Harper Collins, 2015). Neophytes are plants introduced to the British Isles after 1492.

Note 2 – Gillian Beckett, Alec Bull and Robin Stevenson, ‘A Flora of Norfolk’. Privately published. (1999).

Note 3 – The Ted Ellis Trust. ‘Wildflowers of a Broadland Reserve Wheatfen. Part 1: Species of the fen and reedbeds.’ (Written by Will Fitch, the current warden.)

Note 4 – My first encounter with Ted Ellis was as a child, when I had several of his wildlife guides, packed full of photographs, published in Norwich by Jarrold Colour Publications and written by “E.A. Ellis”. At the time I didn’t imagine I would one day live in Norwich.

After his death, the Ted Ellis Trust was set up to look after Wheatfen.

Note 5 – The Large Copper reintroduction project at Woodwalton Fen ran from 1927 until the early 1990s. Our own sub-species, Lycaena dispar ssp. dispar became extinct in 1851 (or perhaps as late as 1864), so the Dutch subspecies, Lycaena dispar ssp. batavus, was used.

I visited Woodwalton Fen on a Botany field trip in 1983 and while I was there I saw several Large Coppers flying in the warden’s greenhouse, but sadly not in the wild.

‘The Butterflies of Britain & Ireland’ by Jeremy Thomas and Richard Lewington (British Wildlife Publishing, 2014) gives more useful information.

Alder Tongue, Taphrina alni

Jeremy Bartlett's LET IT GROW blog Posted on by
Alder Tongue, Taphrina alni

Alder Tongue, Taphrina alni. Upton Fen, August 2020.

At this time of year we go looking for Alder Tongue fungi, Taphrina alni. We usually find some on the Alder trees by the River Wensum at Sweetbriar Marshes in Norwich, not far from where we find Alder Goblets in the late winter.

So last Sunday afternoon we went to have a look. We saw several, on the lower branches of Common Alder trees beside the tarred path that runs between the Mile Cross and Sweetbriar Road bridges.

Alder Tongues are a type of plant gall. The Ascomycete fungus Taphrina alni infects an Alder tree and produces chemicals that alter the growth of the woody female catkins (pseudocones), producing the distinctive tongue-like growth, which can grow to at least twice the length of the catkin. The structure is sometimes known as a “languet” (something that resembles a tongue).

The “tongue” tissue derives mainly from the ovarian tissues of the alder catkin or from its bracteoles. (Apparently those curling down usually come from the bracteoles tissues and those projecting upwards usually come from ovarian tissues.) Alder Tongues are smooth-edged and grooved and usually curved.

The fungus produces sexual spores from its asci, which are embedded in the gall tissue, and these are carried by the wind to infect other trees. Often a single female catkin has several Alder Tongues growing from it but sometimes the gall doesn’t develop properly – the Plant Parasites of Europe website has photographs of a gall that has failed to grow.

Alder Tongues can be green, cream, red, purple or brown. Specimens produced early in the season (July or early August) tend to be green, whereas later specimens (mid August onwards) are usually more richly coloured. Old Alder Tongues are brown and the dried structure persists into winter on the mature, browny black pseudocones. They may still be attached to fallen pseudocones in late winter.

Alder Tongue, Taphrina alni

Young, fresh Alder Tongue, Taphrina alni. Sweetbriar Marshes, Norwich, last week.

Alder Tongue, Taphrina alni

Older, brown, Alder Tongues, Taphrina alni. Sweetbriar Marshes, Norwich, last week.

Taphrina alni has been recorded from many parts of the British Isles, though mainly north of a line from the Thames and Severn estuaries. It has been found as far north as Orkney. (The NBN Atlas had 654 records at the time of writing.) It appears to be becoming more common, with an increase in sightings since the 1990s.

Outside the British Isles, Taphrina alni occurs in several European countries, including Germany, Switzerland, Norway and Denmark. It is has also been found in the USA and Canada.

Other species of Taphrina also cause gall formation in their hosts.

Taphrina betulina causes a gall known as a Witches’ Broom, a dense twig-like formation in the branches of a birch tree. It is the size and shape of a squirrel’s drey and is most obvious in winter, once birch trees have lost their leaves. (But beware: similar growths can also be caused by several other organisms, including other fungi, insects, mites, nematodes and viruses.)

Pocket Plums are caused by Taphrina pruni. The fungus infects Blackthorn (Prunus spinosa) and other species of Prunus, included domesticate varieties of Plum. Infected fruit develop into elongated green structures that resemble small runner beans. affected fruit have no stone.

There are some good photographs of Alder Tongues on the NatureSpot, Living Levels and Botany In Scotland websites.

Dodder, Cuscuta epithymum

Jeremy Bartlett's LET IT GROW blog Posted on by

“The wonder of the world
The beauty and the power
The shapes of things,
Their colours, light and shades
These I saw,
Look ye also while life lasts.” (note 1).

Common Dodder, Cuscuta epithymum

Common Dodder, Cuscuta epithymum. Bryant’s Heath, Norfolk, mid July 2021. (The purple in the background is Bell Heather, Erica cinerea.)

My Favourite Vampire

For some people it’s Dracula, but my favourite vampire is Common Dodder, Cuscuta epithymum. It is always a pleasure to see it, with its stems twining like pink spaghetti or silly string over gorse and Heather.

Cuscuta epithymum is a member of the Convolvulaceae (Bindweed family) and twines its stems over vegetation like its leafy green relatives Field Bindweed (Convolvulus arvensis) and Hedge Bindweed (Calystegia sepium). But Dodder is a parasitic plant with much smaller flowers and small, scale-like leaves. It lacks chlorophyll and depends on its host plant for its supply of nutrients (note 2).

In Norfolk, Common Dodder grows on sandy, acid heaths, including Kelling Heath, Buxton Heath, Holt Lowes and Bryant’s Heath and parts of Beeston Common. Here, it sprawls low over the ground, but at Incleborough Hill, near West Runton, Dodder it grows to a massive size as it clambers over Common Gorse bushes.

In Norfolk Common Dodder’s hosts are gorse (Common Gorse, Ulex europaeus and Western Gorse Ulex galii) and Ling (Calluna vulgaris) and these are the commonest host plants, according to Stace (note 3). But Cuscuta epithymum will parasitise a wide range of plants, including Common Hawthorn and especially clovers (Trifolium sp.) and other members of the Pea family (Fabaceae) such as Dyer’s Greenweed (Genista tinctoria). It is sometimes called Clover Dodder or Alfalfa Dodder because of its host plants. In the British Isles Cuscuta epithymum sometimes parasitises Wild Thyme (Thymus polytrichus) and in southern Europe it grows on Conehead Thyme (Thymus capitatus), where it apparently takes on the pungent smell of is host. Its specific name, epithymum, comes from growing on thyme.

In the British Isles Common Dodder is most abundant in the south of England but occurs as far north as Fife in Scotland and in parts of Wales and Ireland. As well as heathland, it grows on chalk downland and fixed dune grasslands and sometimes as a casual on field crops and in arable field-borders at the northern and western limits of its range. Dodder has declined since the 1930s as its habitats have been lost, through ploughing of downland and increase in scrub and the destruction of lowland heaths through forestry and house building.

Dodder flowers

Common Dodder flowers

Common Dodder flowers from July to September in the British Isles, but much earlier in southern Europe. (The First Nature website has photographs of the plant flowering in early April in Crete.) The flowers can be pollinated by insects or self-pollinated. Dodder flowers sometimes smell of rotting fish (perhaps to attract Blowflies as pollinators). In contrast, the Plants For a Future website refers to the “remarkably sweet perfume” of the flowers, which is “especially pronounced towards evening“. I sniff the flowers whenever I remember to, but I’ve never noticed much scent (but see update July 2023).

Common Dodder is a native of Europe, West Asia and northern Africa but has also been introduced into North America, South America, Japan, Australia and New Zealand. It is also found in parts of eastern and southern Africa, either as a native or introduction. Across its range there are at least two subspecies and, within these, several varieties. These are distinguished by differences in their flower structure as well as the number of flowers and how they are grouped.

Common Dodder can grow as an annual or perennial plant.

It has small seeds (about 1 millimetre in diameter) and these can lie dormant for years. But seeds cannot live ever and if an area of heathland remains unmanaged for a long period of time Dodder may be unable to survive.

If the conditions are suitable Dodder seeds will germinate as the weather warms up in spring (from April onwards). When the seed germinates, a swollen, root-like organ emerges from the seed case and seeks out a suitable host (note 4). At this stage the plant is using nutrients stored in its seed and it must find a host plant quickly or it will die.

Once a host is found, Dodder attaches to it with a sucker and forms a haustorium (a structure that penetrates the host’s tissue and draws in nutrients; see my post on Mistletoe). The root-like organ withers and from this point onwards nutrients are taken from the host plant through the haustorium and the Dodder starts to grow very rapidly, twining anti-clockwise around its host (as does bindweed, note 5). It is vital that the plant stays attached to its host and the Dodder produces a kind of glue to ensure this happens.

Common Dodder can also grow as a perennial by forming an overwintering gall within a stem of its woody host. In autumn the twisting stems die back but the Dodder survives and produces new growth in the spring. This strategy removes the risk of not being able to find a host (note 6).

Gerald Durrell refers to Common Dodder in his book “The Amateur Naturalist” (note 7). It’s a moment of high drama: “In the heath communities of the south you can find the innocent-looking common dodder. This has no leaves but a hard red stem and clusters of delicately-shaped pink flowers. But don’t be misled by its appearance, for it is a sort of plant Dracula. It climbs up its victim anticlockwise and the roots from its wiry stem pierce the flesh of its host and suck out the nutrients. In some cases the dodder, like Dracula, leaves its victim dead, drained dry.”

Dodder can undoubtably affect the vigour of its host plant but killing the host is not in a parasite’s best interests and growth is usually dependant on the vigour of the host plant.

The Plants for a Future website gives a number of medicinal uses for Dodder, including problems with the liver and gall bladder, urinary complaints and gout. It warns that the plant should not be used by anyone suffering from haemorrhoids. During medieval times, Dodder was used as a cure for depression, but its consumption apparently causes thirst and dryness of the mouth.

My most recent sighting of Common Dodder was at Bryant’s Heath, near Felmingham in North Norfolk. Most of the Dodder was the usual pink colour, but some of the plants were yellow.

Common Dodder with yellow stems and flowers.

Common Dodder with yellow stems and flowers. (You can see some pink strands as well.)

The pink in wild type Common Dodder stems is due to the presence of anthocyanins (cyanidin glycosides) (note 8). The yellow plants must have a block in the anthocyanin biosynthetic pathway. Stace (note 3) mentions these occasional variants: “stems reddish except yellowish in rare albinos”.

A quite separate plant is Yellow Dodder, Cuscuta campestris. This is a North American plant that is sometimes accidentally introduced to fields (where Carrot is one of its hosts) or in bird food mixes. I saw it growing at Natural Surroundings in North Norfolk a few years ago and it persisted in a friend’s garden on the outskirts of Norwich for several years.

The third species of Cuscuta in the British Isles is Greater Dodder, Cuscuta europaea, which usually grows on Stinging Nettles (Urtica dioica), often near water. It is rare and I have yet to see it.

Mike Crewe’s Flora of East Anglia website has some good pictures of all three species on one page for easy comparison.

Notes

Note 1 – I love this quote. It originally comes from a Cumbrian gravestone. It was used by the naturalist, illustrator and author BB (Denys Watkins-Pitchford) in his preface to “Down the Bright Stream”, the second of his books about the last four gnomes in Britain (the first is “The Little Grey Men“). The gnomes are led by Dodder, the oldest and grumpiest gnome, and this provides my feeble excuse for including it here.

Note 2 – Other completely parasitic plants I’ve written about include Ivy Broomrape, Purple Broomrape and Purple Toothwort.

Note 3 – Clive Stace, “New Flora of the British Isles“, pages 603 – 604. (Fourth Edition, 2019.)

Note 4 – Common Dodder “sniffs out its hosts, by recognising their chemical signature”. https://www.nationaltrust.org.uk/west-runton-and-beeston-regis-heath/features/the-amazing-world-of-dodder-cuscuta-epithymum.

There are some good – and a bit creepy – videos of various species of dodder on You Tube, such as https://www.youtube.com/watch?v=5gPuXtmrP0E.

Note 5 – As mentioned in the Flanders and Swann song “Misalliance”, on their album “At The Drop of a Hat”, although the song is really a commentary on politics and class rather than Botany.

“The fragrant honeysuckle spirals clockwise to the sun,
And many other creepers do the same.
But some climb anti-clockwise, the bindweed does, for one,
Or Convolvulus, to give her proper name.” – Flanders & Swann.

You can listen to the song on You Tube at https://www.youtube.com/watch?v=WhJ1MDfvix4.

Note 6 – The information in the previous four paragraphs mainly comes from the Kew Gardens website, http://powo.science.kew.org/taxon/267419-1. The direct contact between species of Cuscuta and their hosts is one of the reasons why Cuscuta species are the most rapidly growing parasitic plants.

Note 7 – Gerald Durrell with Lee Durrell, “The Amateur Naturalist”, Dorling Kindersley (1982), page 72.

Note 8 – See page 121 in the 1941 paper by Beale, Price & Sturgess, “A survey of Anthocyanins VII. The natural selection of flower colour”,  https://royalsocietypublishing.org/doi/pdf/10.1098/rspb.1941.0008.

Update July 2023

On 20th July 2023 I visited Buxton Heath and had another sniff of Dodder. This time the flowers had a distinct not very pleasant scent that combined sweetness and decay.

There were no Blowflies but the flowers were attracting Bee-wolves (Philanthus triangulum). These large, impressive wasps are now common in southern England, having spread rapidly since the 1990s. We now have them visiting our garden (they love Echinops flowers) and they nest on road verges in Norwich. Females catch worker Honeybees to stock their nest holes and feed their larvae.

Bee-wolf on Dodder flowers

Bee-wolf (Philanthus triangulum) on Dodder flowers. Buxton Heath, 20th July 2023.