Red Valerian, Centranthus ruber

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Red Valerian with Small Tortoiseshell

Small Tortoiseshell butterfly on Red Valerian

New Year started well, with sightings of three Otters on our local stretch of river and four Waxwings by our local church, just visible from the kitchen window. But it’s rather cold today and definitely time for another blog post.

At this time of year, there are two choices: write about something seasonal (like Winter Heliotrope, Mistletoe or Ivy) or escape to memories of summers past. I’ve chosen the latter and today I’m writing about Red Valerian (Centranthus ruber).

Red Valerian comes from the Mediterranean area: the Azores, southern Europe and North Africa. It is a native in parts of Albania, Algeria, The Azores, Balearic islands, Corsica, France, Greece, Italy, Morocco, Portugal, Sicily, Spain, Tunisia, European Turkey and the former Yugoslavia. It has been introduced into many other countries, including New Zealand, parts of the United States (including California and by the Puget Sound in Washington) and in the United Kingdom and Ireland. In South Africa it is classed as an invasive plant, and may not be owned, imported into South Africa, grown, moved, sold, given as a gift or dumped in a waterway.

In the British Isles Red Valerian is a neophyte and was being grown as a garden plant by 1597. It was first recorded in the wild in Cambridgeshire in 1763 and is now thoroughly naturalised in lowland areas. It is frequently found in well drained, disturbed areas such as sea cliffs, limestone rock outcrops and pavements, rocky waste ground, in quarries, on railway banks, on old walls and on buildings. In most of England and Ireland Red Valerian grows inland as well as on the coast, but in Scotland it is more of a coastal plant. There are records as far north as Shetland. The plant is given a hardiness rating of H5 by the Royal Horticultural Society (RHS) – hardy in most places throughout the UK even in severe winters (-15C to -10C). I have fond memories of Red Valerian growing on south-facing cliffs on the Isle of Wight, in shingle at Dungeness (Kent) and Shingle Street (Suffolk) and, as a child, on the North Wales coast.

There are about twelve species of Centranthus and they form part of the Caprifoliaceae (Honeysuckle family). Centranthus ruber can grow as a hardy perennial or a short woody plant (subshrub). We grow it in our front garden, where it dies back in the winter and so behaves more like a hardy perennial. The grey-green leaves grow in opposite pairs and the spurred flowers, which have five petals, grow in clusters on stems up to about a metre (nearly three feet) tall.

It is not surprising that Red Valerian is very popular garden plant. It thrives in sun but will tolerate some shade too. The flowers come in at least three different colours, including pink (the commonest form), white (form ‘Albus’, which is off-white with a pinkish tinge, and ‘Snowcloud’, which has the purest white flowers) and red (form ‘Coccineus‘, which is deep red, and ‘Atrococcineus‘, which is a darker carmine-red) (note 1). I grow the pink form and ‘Albus’. The former grows rampantly but ‘Albus’ seems less vigorous. The plants flower here in Norfolk from May throughout the summer until September or October. In milder areas such as Cornwall they can be in flower at Christmas. The First Nature website has some lovely pictures of the flowers, including close-ups and different colour forms. If you want to propagate a particular colour form, you will need to take cuttings. The flowers can have a distinctive scent, usually described as ‘somewhat rank‘. The Scottish Rock Garden Club Forum has an interesting discussion about the scent and different colour forms.

Red Valerian produces masses of tufted seeds that are dispersed by the smallest of air movements. In our garden, Red Valerian is gradually spreading to the back garden. We don’t really mind, but the plant definitely has the capacity to become a “weed” for some gardeners and the RHS website has advice for growing Red Valerian, as does Gardening Know How, while the Gardeners’ World website has advice if it becomes a problem. The plant has deep roots, which allow it to grow in dry places but can sometimes cause damage to walls. If you cut the dying flowers back you will reduce the amount of self-seeding and prolong the flowering period.

So far I’ve used the name ‘Red Valerian’ for Centranthus ruber, but like many plants there are lots of alternatives and other English names include Jupiter’s Beard, Drunkards and Sweet Betsy (note 2), Keys of Heaven (note 1), Spur Valerian, Kiss-me-quick, Fox’s Brush and Devil’s Beard. The latter presumably comes from the seed heads. The name Centranthus  comes from the Greek words kentron (a spur) and anthos (a flower); ruber means red.

I haven’t tried eating our Red Valerian but the young leaves are edible raw or cooked and can be used in soups. The roots can also be cooked.  Margaret Grieve (note 3) thought that the leaves were “exceedingly good, either in salads or cooked as a vegetable”, but the authors of the Plants For A Future website aren’t so sure: “This differs from our own experience, whilst the leaves can be added to salads they are rather bitter and rather less than desirable”. Richard Mabey says that the very young leaves are sometimes boiled with butter as greens or eaten raw in salads in France and Italy (note 4). According to The Urban Veg Patch website, Mark Diacono “reckons that the leaves have a taste reminiscent of broad beans” (note 5). It is possibly a taste that needs to be acquired.

Medicinally, the Paghat’s Garden website says that “the flowers, young shoots, roots and soft young leaves [of Red Valerian] are a folk remedy for cold, flu, or cough, even though almost certainly ineffective”. The Plants For A Future website agrees that Red Valerian “has no known medical properties“. Apparently Red Valerian seeds were sometimes used in embalming.

Red Valerian is a good plant for insects, including butterflies and bees. As well as the Small Tortoiseshell featured at the top of this blog post, I have photographed Clouded Yellow, Glanville Fritillary and Painted Lady butterflies on the flowers – at Shingle Street, on the Isle of Wight and in our garden respectively. I’ve also seen the flowers uses as a source of nectar for Anthophora quadrimaculata (the Four-banded Flower Bee) in our garden and, in 2018, by St. Giles’ Church in the centre of Norwich (although Catmint is more popular). The Humming-bird Hawkmoth loves the flowers and other moths such as the Angle Shades will feed on the leaves.

This spring, sharp-eyed James Emerson visited our garden and spotted leaf-roll galls on our Red Valerian plants. The galls are formed by the psyllid (jumping plant louse), Trioza centranthi. This insect was a historically rare and scattered species but it seems to be spreading and there have now been several records in Norfolk. Later in the season the galls become more obvious, especially on pink and red-flowered plants, where they stand out from the rest of the leaf (note 6). I’m pretty certain that 2018 is their first year in our garden.

Trioza centranthi leaf-roll gall on a Red Valerian leaf (early May 2018).

Notes

Note 1: The name ‘Keys of Heaven’ and descriptions of colour forms come from the “RHS Encyclopedia of Perennials” (2011; Editor-in-chief Graham Rice, Dorling Kindersley, London).

Note 2: Richard Mabey (1996): “Flora Britannica“, Sinclair-Stevenson, London. Page 350. ‘Drunkards’ probably comes from the plant’s habit of nodding tipsily in the wind.

Note 3: Margaret Grieve (1931), “A Modern Herbal“. Reprinted in 1996 by Barnes and Noble / Random House. Quoted on the Plants For A Future website.

Note 4: Richard Mabey (1975), “Food For Free”, Fontana, Glasgow. Page 106.

Note 5: Mark Diacono (2015) “The New Kitchen Garden“, Hodder and Stoughton.

Note 6: When I wrote this on 3rd January 2019 I hadn’t seen the galls on white-flowered Centranthus ruber plants, but had been told that when they occur they are apparently green like the rest of the leaf, rather than pink. (This would make sense as the white-flowered plants presumably have a block in the biochemical pathway for the synthesis of anthocyanins, which give the pink and red flowers their colours.) On 4th January I found a gall on a white-flowered plant and it had no obvious red pigment.

The “British Plant Galls” Facebook group has just started a citizen science ‘Trioza centranthi gall colour project’ to investigate the correlation between flower and gall colour. If you join the group, you can take part in it.

Hemlock Water Dropwort, Oenanthe crocata

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Hemlock Water Dropwort, Oenanthe crocata

Hemlock Water Dropwort, Oenanthe crocata. In flower, Isle of Wight, mid May 2016.

Fancy a curry? I do, and I like foraging for food, but I won’t be using Hemlock Water Dropwort, Oenanthe crocata. Here is a cautionary tale.

About twenty years ago a group of eight young adults on holiday in Western Scotland found what they thought were Water Parsnips growing in a small stream. They picked them and added them to a curry (note 1).

By the next morning, one person, who had eaten more than the rest, was having seizures and other members of the group felt unwell and nauseous. In spite of this, four people ate the leftover curry for lunch and one of this group also had a seizure. Fortunately the police were able to take one of the group back to the stream to collect a sample of the plant, which was identified by a local botanist and following treatment in the local hospital all of the group recovered (note 2).

Hemlock Water Dropwort, Oenanthe crocata, is a fast growing perennial plant of wetlands, streams, ditches and the margins of rivers. It is a member of the Apiaceae (Parsley family) and its flowers are arranged in the family’s characteristic umbels. I have previously written about several members of this family, most recently Wild Carrot (Daucus carota).

There are eight species of Water Dropwort (Oenanthe) in the British Isles, all of which are poisonous. Oenanthe crocata is found mainly in the south and west, including Scotland and Ireland, mainly in lowland areas (note 3). Its stems elongate in spring and it flowers from May to July, depending on location. In 2016 it was flowering on the Isle of Wight in mid May, while in the Oban area in May 2018 the plant was in leaf or in bud. There are some excellent close-up photographs of the plant at different stages of growth on the internet, including the Wildflower Finder and First Nature websites.

It is well worth being able to identify Oenanthe crocata as it is probably “the most toxic plant in Britain to both humans and animals“. Its leaves look lush and tempting and remind me of Flat-leaved Parsley, Petroselinum crispum var. neapolitanum, which I grow on my allotment. Both plants have smooth, hairless stems and leaves and Hemlock Water Dropwort’s leaves have a similar smell to parsley but Flat-leaved Parsley never grows in wet ditches. The lush growth and smell are also a bit like Wild Celery, Apium graveolens, which also grows on wet ground but mostly in the south.

“Oenanthe” is derived from the Greek words oinos “wine” and anthos “flower”, from the wine-like scent of the flowers (note 4). “Dropwort” comes from the (slight) resemblance of some smaller species of Oenanthe to Dropwort, Filipendula vulgaris, which grows in dry grassland and whose root tubers hang like drops from its roots.

All parts of Hemlock Water Dropwort are toxic to mammals. Cattle can eat small quantities of the leaves with no ill effect, but not the plant’s white, fleshy tubers, which are the most toxic part of the plant. They are normally hidden below ground but may be exposed by poaching by cattle, or by flooding or enthusiastic curry-eating foragers. The level of toxins is highest in late winter and early spring, when the plant’s foliage has died down. The tubers are sometimes known as “Dead Mans Fingers” as they typically occur in groups of five or more. They exude a yellowish liquid when cut, which stains the skin.

The main poisonous substance in Hemlock Water Dropwort is a polyunsaturated higher alcohol called Oenanthotoxin. Its direct effects are on the central nervous system, which results in a large number of unpleasant effects, listed here. They range from slurred speech, dizziness and nausea to spasms, acute renal failure and cardiac arrest. The Wildflower Finder website gives more details of the plant’s biochemistry. Research has also been carried out on the plant’s essential oil’s antifungal, antioxidant and anti-inflammatory properties (note 5).

As well as a knowledge of Botany, a knowledge of History comes in handy when you’re sourcing ingredients for a curry. There have been at least fourteen cases of Hemlock Water Dropwort poisoning in the UK in the 20th Century. The Poison Garden website lists a number of cases of poisoning, ranging from a mild (but nonetheless unpleasant) case of poisoning by eating the leaves to stories from the 1970s and 1980s and as far back as the Napoleonic Wars. The latter incident involved eleven French prisoners in Pembrokeshire, two of whom died. John Robertson, the author of the Poison Garden website gives more details in his excellent book “Is that Cat Dead?” (note 6).

One of the symptoms of Oenanthotoxin poisoning is a spasm of the facial muscles known as a sardonic grin (risus sardonicus), although a sardonic grin may also be caused by tetanus, strychnine poisoning or Wilson’s disease. In Sardinia in the pre-Roman Nuragic culture, a “sardonic herb” creating this spasm was used for the ritual killing of elderly people. Italian scientists have suggested that the herb may have been the close relative Oenanthe fistulosa. (O. fistulosa is known as Tubular Water Dropwort in Britain.) (note 7).

Oenanthotoxin is thought to be absorbed through the skin, so try not to splash yourself with the plant’s sap. Artists should heed the warning from  the German eighteenth century botanical illustrator Georg Ehret, who found that Hemlock Water Dropwort made him giddy when he was drawing it in an enclosed room. Fortunately his solution – to open the windows to allow fresh air to circulate – was completely successful (note 8).

Although Hemlock Water Dropwort is poisonous to mammals, its flowers are attractive to insects, including Marsh Fritillary butterflies, as photographed by Ray Cannon in Galicia in north-west Spain. My friend Stuart, based in Cornwall where Hemlock Water Dropwort is abundant, tells me that beetles (including flower, longhorn and soldier beetles) and flies (including hoverflies) are especially fond of the flowers.

Hemlock Water Dropwort leaves

Hemlock Water Dropwort leaves, looking rather like Flat-leaved Parsley. Near Oban, mid May 2018.

Notes

Note 1: It does make you wonder why they thought this was a good idea. There are two British plants commonly known as “Water Parsnip”, both of which grow by and in fresh water. Berula erecta, Lesser Water Parsnip, is the most widespread and reaches the south of Scotland and Sium latifolium, Great Water Parsnip, is a scarcer Fenland plant. Both are poisonous, although Sium latifolium leaves have been cooked in Italy and its seeds have been used in small quantities as a spice in Scandinavia. The roots are sometimes compared to “white carrots” but apart from the fact that they grow undergound, they don’t look similar to me.

Note 2: Downs C, Phillips J, Ranger A, et al (2002). “A hemlock water dropwort curry: a case of multiple poisoning”. Emergency Medicine Journal  Vol. 19: pp 472-473. The article is available online and makes an interesting read.

Note 3: Oenanthe crocata also grows elsewhere in Europe. It has also recently been recorded in the Buenos Aires area of Argentina as an introduced plant.

Note 4: Not to be confused with the bird with the same generic name, the (Northern) Wheatear, Oenanthe oenanthe. The bird is called Oenanthe because the birds return to Greece in the spring just as grape vines are in blossom.

Note 5: Valente, Júlia & Zuzarte, Mónica & Gonçalves, Maria & Lopes, Mc & Cavaleiro, Carlos & Salgueiro, Ligia & Cruz, Mt. (2013). “Antifungal, antioxidant and anti-inflammatory activities of Oenanthe crocata L. essential oil.” Food and Chemical Toxicology  Vol. 62.

Note 6: John Robertson (2010), “‘Is That Cat Dead?’ and other questions about poison plants”. Book Guild Publishing, Sussex, England. The book is now quite hard to find.

Note 7: Giovanni Appendino, Federica Pollastro, Luisella Verotta, Mauro Ballero, Adriana Romano, Paulina Wyrembek, Katarzyna Szczuraszek, Jerzy W. Mozrzymas, Orazio Taglialatela-Scafati (2009). “Polyacetylenes from Sardinian Oenanthe fistulosa: A Molecular Clue to risus sardonicus“, J. Nat Prod. Vol. 72(5): pp 962–965.

Note 8: Richard Mabey (1996): “Flora Britannica“, Sinclair-Stevenson, London. Page 289.

Gardening For Wildlife

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Regular readers will know that, as well as plants and fungi, I love wildlife. For me, a garden is not complete without its range of wild creatures, ranging from the birds and mammals that visit and sometimes stay for a while, down to the smallest invertebrates that live out their entire lives amongst the plants, in the leaf litter or in the soil.

Our back garden

Our back garden, June 2018

The natural world is under increasing threat from climate change, habitat destruction, pollution and too many humans using too many natural resources. More locally, road and house building, the paving of front gardens and the routine use of toxic substances (in agriculture, by some households and by most local authorities) are all causing harm.

Gardening with wildlife in mind makes our home environment much pleasanter and more interesting but also it helps to provide somewhere for other species to live and thrive.

If you want to read about wildlife gardening, the Wildlife Gardening Forum and the RSPB’s ‘Give Nature A Home In Your Garden’ websites are very good places to start.

Last summer I led a workshop on wildlife gardening and came up with some of my own general principles on wildlife gardening, a couple of which I have written about below. I hope you will find them useful.

What each of us can do in our own garden will depend on our own circumstances, such as the size of our garden, the amount of time we have available and where we live, but these are general principles which can be applied to most gardens.

It All Starts With Plants

When creating a garden it is customary (and sensible) to start with basic structures, such as fences around the perimeter and the position of paths, patios, sheds, washing lines, lawns, ponds and other hard landscaping features. However, from the perspective of wildlife, it is plants that form most of the fabric of a garden and provide shelter and food. For wildlife, it all starts with plants.

Flowers provide food in the form of nectar and pollen and, in return, insect visitors act as pollinators. Recent attention, such as Friends of the Earth’s The Bee Cause campaign has focussed on bees, which include bumblebees and many species of solitary bees as well as the more familiar and mostly domesticated Honeybee. However, other insects such as flies, beetles and wasps, all play their part.

Many kinds of garden wildlife feed on living plants. Leaves can support caterpillars of butterflies and moths, while roots of grasses in the lawn can support charismatic microfauna such as Cockchafer beetles. Some herbivores can be regarded as pests but in a well-balanced garden this only happens rarely (even with slugs and snails).

Cockchafer beetle

Cockchafer beetle

Plants are also the source of rotting and dead material, which is another food source. Dead leaves provide food for earthworms and invertebrates, fungi and bacteria help to break down dead plant matter on the compost heap.

The Wildlife Gardening Forum gives some basic principles for planting but the choice of what to plant is very wide.

Some plants are better for wildlife than others. Highly bred plants with double flowers and/or little or no pollen are of no use to bees and other pollinators, so don’t fill your garden with them. But not all bedding plants are bad – I find that  hoverflies and some solitary bees like trailing Lobelia (Lobelia erinus) flowers.

Avoid invasive flowers which may become a nuisance to you, your neighbours or in the wider countryside. The Wildlife Gardening Forum gives some good advice on this. Beware of invasive pond plants such as New Zealand Pigmyweed. We inadvertently bought it from a garden centre and introduced it into the pond at our previous house and spent two summers getting rid of it.

I personally wouldn’t be without Viper’s Bugloss, Teasels and Oxeye Daisies and don’t find them to be a problem. Stinging Nettles (Urtica dioica) grow in next door’s garden, so I don’t grow them at home because they’re rather invasive, but I’ve found room for a patch at the allotment, where they provide food for caterpillars of Small Tortoiseshell and Peacock butterflies.

I aim to have something in flower from early spring (February or March) through to autumn (October and November) and plants with a wide variety of flower shapes, to attract as many different insects as possible: hardy Geraniums, open-topped flowers like Wild Carrot and long-tubed flowers such as Catmint. (If you read other posts on this blog you’ll see what I like.) I grow a mix of native and non-native plants: both can be good for wildlife.

Sometimes I grow a plant just because I like its spectacular or interesting form, only to find that wildlife quite like it too. I planted Gunnera manicata because I like its spectacular leaves but I found our House Sparrows loved sitting on them and a visiting Fox cub sheltered in the shade the plant one spring. Tetrapanax papyrifer flowers late in the year (and often not at all). But when it does flower, its ivy-like blooms are attractive to Bombus terrestris bumblebees and Honeybees and in the summer insects bask on the leaves. Tree Tobacco flowers are pollinated by hummingbirds and sunbirds in some parts of the world but don’t attract insect pollinators in our garden. However the plant as a whole provides shelter for birds, including Blue Tits and Wrens, which hunt amongst the branches for caterpillars and spiders respectively.

As well as your budget and personal taste, the size and aspect of your garden will have a big influence on what you grow.

It is important to choose the right plant for the right place. Plants like Lavender, Catmint and Perennial Wallflowers like sun or semi-shade and prefer well drained soils. Other plants prefer shade or damp areas, while some will only grow on acid or alkaline soils. While many plants are quite adaptable, there is no point in fighting nature – a Rhododendron will never like chalky soil.

Be realistic with what you might attract to your garden, too. In the Isle of Wight, Ribwort Plantains may attract Glanville Fritillary butterflies, but they are not likely to do so in other parts of the British Isles where the butterfly doesn’t occur. But they may attract other wildlife and if you like growing them (which I do), why not?

Build Up The Layers

When creating a garden, complexity is good. Different animals like using different layers of planting and the more layers the better. Birds are more likely to visit the garden and nest if there are trees and shrubs. While hedges are great habitats, it is often more practical to grow climbers up fences and these can also soften edges  of buildings too.  I grow various climbers, including several varieties of Honeysuckle, Clematis, Chocolate Vine and Chinese Virginia Creeper. I’m a fan of Ivy, but we don’t grow it in the garden as it can be very rampant, though we plan to grow it as an “ivy bush“. When we moved here five and a half years ago, our garden had a lawn, gravel and slabs. We attract birds to the garden by feeding them, but it is only since trees and shrubs have matured that they stay around longer.

It’s worth looking at your garden from the point of view of a bird or insect. What do you need to do to attract different species?

For example:

Bees need food (pollen & nectar), a nest site in a sunny place (holes in walls, logs, hollow stems, snail shells, rough grassland, compost heaps, bare or sparsely vegetated ground bird nest boxes), building materials (mud for mason bees, leaves for leaf-cutter bees, hairy leaves for Wool Carder Bees), sunning places to bask, groom or mate, and sometimes water (such as a pond or bird bath that Honeybees in particular will use to drink and collect water to cool their nest).

Frogs need a pond in which to breed but also the cover of vegetation, where they will spend much of their adult life away from water. A log pile will provide cover for their invertebrate food.

A Blue Tit needs a nesting site (and readily uses nestboxes). Nuts and suet pellets will supplement the adult’s diet but it also needs a good supply of insects, particularly caterpillars, to feed its young. A Blackbird will nest in cover, such as a large shrub, hedge or climber and use a garden lawn as a hunting ground for earthworms. In autumn it will be attracted to berries on shrubs and trees, such as Rowan.

A Holly Blue butterfly will visit plants with nectar. (I’ve seen them feeding on exotics like Curry Plant and Canadian Goldenrod.) But they also need Holly and Ivy plants to lay eggs, where their caterpillars can feed.

Similarly, what does a Violet Ground Beetle, Brown Hawker dragonfly or a Hoverfly need?

Atlas Poppy and hoverflies

Atlas Poppy (Papaver atlanticum) with three different hoverflies, including Episyrphus balteatus (top left) and Dasysyrphus albostriatus (bottom right).

No garden can supply everything, and may only be attractive for part of an animal’s lifecycle, but a garden with a number of layers, plus a lawn and a pond will provide food and shelter for a wide variety of wildlife.

We are building up a decent species list for our garden, including over 350 species of moths, 21 species of butterflies, 37 species of hoverflies, 60 species of bees, nearly 50 species of birds (including ones flying through our air space), Hedgehogs, Smooth Newts, Common Frogs and 7 species of woodlice. It is amazing what is living just yards away from us.

Update December 2019: My wife has started a blog, “Arthropedia“, describing the invertebrates we have found in our garden and further afield.