Lungwort, Pulmonaria officinalis

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Lungwort, Pulmonaria officinalis

Lungwort, Pulmonaria officinalis. Growing at the base of an east-facing wall in a garden in Kelling, North Norfolk, early April 2018.

Spring has arrived all of a sudden, with record-breaking February temperatures in parts of Britain. While it has been lovely out in the sunshine, the unseasonal weather is distinctly unsettling, with our knowledge that the Earth is expected to experience more record-breaking temperatures this year (note 1).

One result of the extra warmth has been the early appearance of hibernating bumblebees, butterflies (Peacock, Small Tortoiseshell, Comma and Brimstone) and the emergence of some solitary bees. One of these has been Anthophora plumipes, the Hairy-footed Flower Bee, which feeds on spring flowers such as Primroses, ‘Bowles’ Mauve’ Wallflowers and Lungwort.

Lungwort, Pulmonaria officinalis, normally starts to flower in March and continues through to May.  It’s a slow-growing perennial plant and has characteristic white spots on its leaves. Like Oysterplant, it is a member of the family Boraginaceae. Unlike Oysterplant, you won’t find it on a beach but in a garden or naturalised in woods, scrub or on waste ground. Lungwort has purple flowers, which start off pink, like several other members of its family.

In the British Isles the plant is an introduction, but it occurs widely in the wild in continental Europe. The plant prefers fairly open shade, a reasonably moist but not waterlogged soil and not too much summer heat. It is hardy to UK hardiness zone H4 (-10ºC to -5ºC). Lungwort flowers lack scent, but bees still are able to find them, possibly (with the ability to see ultraviolet light) as “incandescent beacons, shining like lamps in the semi-shade” (note 2).

The article “Biological Flora of the British Isles: Pulmonaria officinalis” is well worth a read (note 3). It snappily describes the plant as a “distylous, perennial rosette hemicryptophyte“. Distylous means that the flowers come with long and short styles and stamens, rather like pin- and thrum-eyed Primroses. A hemicryptophyte is a plant whose perennating buds are at ground level, the aerial shoots dying down at the onset of unfavourable conditions (such as in the heat of summer).

Like the name Lungwort the scientific name, Pulmonaria, refers to the lungs (Latin Pulmoa) . This is because the plant’s spotty leaves were thought to resemble diseased, ulcerated lungs. The Doctrine of Signatures, used in folk medicine, drew upon the belief that if a natural object looked like a part of the body it could cure diseases that arose there (note 4). Other examples include Liverworts, Spleenwort, Eyebright and Toothwort. The specific name ‘officinalis‘ refers to Lungwort’s use in herbal medicine.

Lungwort leaves have a high mucilage content and have been used externally for the treatment of burns and eczema. Internally, the plant has been used to treat sore throats, as well as chest conditions such as coughs (sometimes in conjunction with Coltsfoot). Lungwort’s phytochemistry has only been investigated very recently (note 5).

Lungwort leaves are edible raw or cooked but the plants growing in my dry garden soil need all the leaves they can grow, just to survive, so I haven’t tried them. Besides, the plant doesn’t exactly have rave reviews on the Plants For A Future website. “A fairly bland flavour… an acceptable addition to mixed salads, though their mucilaginous and slightly hairy texture make them less acceptable when eaten on their own“. Cooked, the young leaves “make a palatable cooked vegetable, though we have found the texture to be somewhat slimy.”

I am not alone in recommending Pulmonaria officinalis and other Pulmonaria species as garden flowers: Lungwort was Plant of the Week in The Guardian in March 2017 and featured in The Telegraph in 2002. The RHS also offers advice on growing the plant. Different Pulmonaria flower colours and leaf shapes are available, as are plants with unspotted leaves. My own favourite remains Pulmonaria officinalis and I have fond memories of it growing in gardens in north-east Scotland.

Two other Lungworts grow wild in the British Isles, but are not common and I haven’t seen them (but see Update – May 2019, below). Both are native, unlike Pulmonaria officinalis.

Narrow-leaved Lungwort, Pulmonaria longifolia, grows in light shade in Hampshire, around the Solent and on the Isle of Wight, and in Dorset, near Poole Harbour. It has narrower, oval, bluish-green lightly spotted leaves and smaller, but “piercingly blue” flowers (note 2).

Unspotted or Suffolk Lungwort, Pulmonaria obscura, grows only twenty miles from home, but is confined to three privately-owned Suffolk woods, which are inaccessible by public transport and only seldom open to public visits. Its name comes from the lack of spots on its leaves, but as I haven’t seen it, I think that “Unspotted” is rather appropriate. The lovely NatureGate website has photographs of this lovely plant, which also grows in southern Finland.

Lungwort is also known by other English names, including Mary-spilt-the-Milk (note 6), Lady’s Milk-drops (from the spots on the leaves), Spotted Dog, Soldiers and Sailors, Jerusalem Sage, Bethlehem Sage and Jerusalem Cowslip. I wonder whether the “Jerusalem” and “Bethlehem” names come from the plant’s Easter flowering time, but I have so far been unable to find out.

Notes

Note 1: The article “Media reaction: The UK’s record-breaking winter heat in 2019” on the Carbon Brief website is well worth a read, and includes Met Office diagrams showing how great the maximum daily temperature anomalies have been.

Note 2: I recommend Peter Marren’s very enjoyable book “Chasing The Ghost – My Search For All the Wild Flowers of Britain” (Square Peg, London, 2018). It has some very vivid descriptions of Lungwort flowers, including Pulmonaria longifolia and P. obscura. He managed to see P. obscura in Suffolk, and found that is “not only attractive and grows in a lovely, wild location, but is also reasonably distinctive and not ‘obscure’ at all”.

Note 3: See Sofie Meeus, Rein Brys, Olivier Honnay and Hans Jacquemyn (1992) – “Biological Flora of the British Isles: Pulmonaria officinalis“.  Reprinted in the Journal of Ecology (2013), 101, 1353–1368.

Note 4: The Swiss physician Paracelsus was an important advocate of the Doctrine of Signatures and thought that “Nature marks each growth… according to its curative benefit“.

Note 5: See Krzyzanowska-Kowalczyk J, Pecio L, Moldoch J, Ludwiczuk A, Kowalczyk M. Novel (2018) –  “Phenolic Constituents of Pulmonaria officinalis L.”  Molecules. 2018;23(9):2277. Thanks to the United States National Center for Biotechnology Information for putting the article online.

Note 6: Richard Mabey (1996): “Flora Britannica“, Sinclair-Stevenson, London. Page 306.

Update – May 2019

I have now managed to see both Unspotted or Suffolk Lungwort, Pulmonaria obscura, and Narrow-leaved Lungwort, Pulmonaria longifolia. In early May I helped with a count of plants in two of the woods where Suffolk Lungwort grows, then in mid May I went to see Narrow-leaved Lungwort while staying on the Isle of Wight. Here are pictures, for comparison with our better known spotty friend:

Narrow-leaved Lungwort, Pulmonaria longifolia

Narrow-leaved Lungwort, Pulmonaria longifolia.

Unspotted or Suffolk Lungwort, Pulmonaria obscura

Unspotted or Suffolk Lungwort, Pulmonaria obscura

Oysterplant, Mertensia maritima

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Oysterplant, Mertensia maritima

Oysterplant (Mertensia maritima) and Sea Sandwort (Honckenya peploides) growing on Orkney.

A few weeks ago a lady from Northern Ireland contacted me and told me about some of the plants she’d seen for the first time in her local area in 2018, one of which was Oysterplant. It’s a favourite of mine, but a plant I rarely see.

Oysterplant, Mertensia maritima, is a beautiful perennial that grows on sand, gravel and shingle beaches. It grows close to the ground with a spreading habit, with blue-grey leaves and, from June to August, clusters of reddish flowers that turn blue as they age, in a similar way to Forget-me-nots and several other members of its family, the Boraginaceae. (I have previously written about some of these: Green Alkanet, Viper’s Bugloss, Navelwort and Abraham-Isaac-Jacob.) There are some lovely pictures of it on the West Highland Flora and UK Wild Flowers websites.

Mertensia maritima has a large taproot that reaches down through sand or shingle to find water, as well as anchoring the plant in its exposed habitat. In winter the leaves die back to ground level. The plant spreads by seed (nutlets) and these can be transported by wind and sea and have been known to travel at least 450 km (280 miles). Germination is unaffected by up to 18 days of immersion in sea water and the seeds are capable of staying dormant for several years, until the right conditions trigger germination (note 1). Flowers appear to be mostly self-pollinated in Northern Ireland but in some places (such as on Svalbard) they are visited by insects.

Sometimes the plant occurs as a casual for just a few years before being washed away by storms but colonies can persist for hundreds of years when conditions are right. (Plants growing in pure sand are usually short-lived.)

Mertensia maritima is very much a plant of northern areas. In the British Isles it can now be found in Scotland (especially Orkney and Shetland) and Northern Ireland. In Northern Ireland it is on a list of Priority Species;  the plant also features in a 1992 article in the Irish Naturalists’ Journal. There are pre-2000 records from Northern England, North Wales and the Isle of Man, but the plant is contracting its range in the south and expanding its range further north. Further afield, the plant grows in Svalbard, Franz Joseph Land, Iceland, Greenland, North-east Asia and North America, including Canada and, in the United States, New England (note 2). Its southern limit more or less corresponds with the mean January isotherm of 4.5 °C and the mean July isotherm of 19 °C.

With its northern distribution, Mertensia maritima may well be adversely affected by climate change (note 3). The Online Atlas of the British Flora gives storms, recreational pressures, shingle removal and grazing as reasons for losses. Like the Sea Pea (Lathyrus japonicus) that I wrote about in August 2017, visitor pressure may be very significant.

Here are some examples of the threats to Oysterplant:

I’ve only seen Oysterplant twice and in both cases the location of the plants made my memories stronger.

I first saw the plant in 1997 on a a three week cycling trip in Iceland. While we were camping in Reykjavik we walked down to the harbour to look at the Sun Voyager. The sculpture was lovely and so was the Oysterplant growing on the shoreline nearby.

The second sighting was on another cycling trip, this time in 2006, on Orkney. We were camping in Kirkwall and decided to visit South Ronaldsay for the day. Cycling south to the Tomb of the Eagles at the far end of the island we crossed the Churchill Barriers (note 4).  Oysterplant was growing in a sandy area next to one of the Barriers.

The leaves of Mertensia maritima are edible, both raw and cooked, as are the flowers and root, but the plant is so uncommon that I don’t recommend picking it from the wild. The name “Oysterplant” comes from the taste of its leaves.

Several plants are described as “tasting like oysters”, including Salsify, which I have written about, and its close relative Scorzonera, but I’m not too convinced about the similarity.

The Plants for a Future website has a similar opinion of Oysterplant. “No-one has yet noticed a resemblance to oysters though not many of the tasters have ever eaten oysters! The flavour is fairly bland, the leaf is thick and has a very mucilaginous texture – it is probably this texture that reminds people of oysters.” I’ve eaten and enjoyed oysters a few times. It is the texture, combined with a fresh sea water saltiness, that defines the experience for me, rather than any strong taste.

But in “Flora Britannica”, Richard Mabey quotes a man in Scotland who has Oysterplant growing on his local beach. “I was once poisoned by an oyster and I can’t abide them. The taste of the leaf made me retch, so true is it to its name” (note 5).

The Edible Wild Food website says that “leaves can be added to salads, and they go quite well with eggs”. The Edible Garden Nursery website suggests that the leaves can be used “in fish dishes or salads.”

Oysterplant is often difficult to cultivate and is very susceptible to slug damage. Plants don’t like root disturbance and are most likely to succeed in well-drained sandy or gravelly soils in a sunny position. I haven’t tried growing it and I suspect it would be too hot for it here in Norfolk. However, if you like a challenge, why not give it a try? If you live in the UK, plants are available (to pre-order) from The Edible Garden Nursery. The Dave’s Garden website lists people in America and Europe who may be able to supply the plant. Oysterplant can also be grown from seed.

Other English names for Oysterplant include Seaside Bluebells, Sea Lungwort and Gray Oysterleaf.

Mertensia is named after the German botanist Franz Carl Mertens (1764 – 1831). The genus also includes American species such as Mertensia ciliata  (Fringed Bluebells) and and Mertensia virginica (Virginia Bluebells).

Notes

Note 1: The germination rate of seeds is increased improved by exposure to temperatures of 2°C or below. The British Wild Plants site is understandably gloomy about the plant’s return to Wales: “… the … seeds … must have a prolonged period in the cold sea water below 5C and then some time on cold pebbly beach in order to scrape the hard outer coat of the nutlets and allow germination to begin. The winter seas around Wales are far too warm now and it will probably never return.”

Note 2: The Flora of Svalbard describes three subspecies of Mertensia maritima. These are ssp. maritima, ssp. tenella and ssp. asiatica. Mertensia martima in the British Isles and New England is ssp. maritima, while ssp. tenella occurs in Svalbard. (I have been to Svalbard but annoyingly, I can’t remember seeing Oysterplant – I think I would have remembered if I had.)  Ssp. asiatica is found by the Pacific Ocean.

Note 3: Mertensia maritima is specfically mentioned in the MCCIP report “Impacts of climate change on coastal habitats” – L. Jones, A. Garbutt, J. Hansom and S. Angus (2013), MCCIP Science Review 2013: pp167-179. Climate change may lead to more storm surges, increases in temperatures and changes to rainfall (see page 172 of the report).

Note 4: The Churchill Barriers were built in the Second World War to protect Scapa Flow from enemy submarines and ships. They are now used as causeways to provide a road link from South Ronaldsay to Orkney’s Mainland, via Lamb Holm, Glimps Holm and Burray.

Note 5:  Richard Mabey (1996): “Flora Britannica“, Sinclair-Stevenson, London. Page 310.

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.