Pulmonaria officinalis – April 13th 2026 – Lungwort
Here is a plant you may see flowering now, especially if you like walking in the dabbled shade of deciduous woodlands with your eyes looking downward at the emerging flora. Lungwort, Pulmonaria officinalis, is found in the understory of deciduous woods. It is primarily a woodland plant, but it grows in the open too – it can be found in parkland, roadsides, derelict sites and banks of rivers. It was introduced to Britain as a garden herb by 1596, cultivated in homes and monasteries for presumed medicinal value and used in garden designs for its value as an attractive plant that tolerates shade. It eventually escaped cultivation and was first recorded in the wild 1793 (southern England).
Pulmonaria officinalis by Johann Georg Sturm (1742–1793) (Painter: Jacob Sturm), Public domain, via Wikimedia Commons.
Please note: several other plants have been called ‘lungwort’ and one of them is the lichen Lobaria pulmonaria. It grows on trees – but we’ll put that one aside for the time being.
Lungwort Pulmonaria officinalis growing ‘in the rough’ at a golf course, Edinburgh. Image: Sue Jury
Lungwort Pulmonaria officinalis is a perennial plant in the Boraginaceae (the plant family of borage, comfrey and forget-me-nots) with a woody rhizome sprouting leaves in early spring, before the trees have formed their canopy. The leaves are spotted1 and resemble diseased lungs, hence its common name ‘lungwort’ from the ancient ‘Doctrine of Signatures’ whereby the appearance of any plant was supposed to suggest its use in medicine. Thus, people would attempt to cure bronchial conditions with lungwort.
Rare form of Pulmonaria officinalis with white flowers. Image: Chris Jeffree.
The presence of rhizomes suggests a capacity for vegetative reproduction, but this is very slow in most British conditions – sexual reproduction and the production of seed is the main method of spread.
Flowers may appear as early March, but usually later (April). They change colour from red to blue as they develop, and there are two types, with different locations of the anthers and pistil. Darwin studied a similar state-of-affairs in primroses (‘pin’ and ‘thrum’ forms) and suggested that the arrangement is a mechanism to encourage cross pollination. Modern work in P. officinalis suggests the mechanism may not be especially efficient. Pollination is by flying insects (early-emerging queen bees may benefit) attracted by the ample supply of nectar in the base of each flower (sometimes it may ferment – we may presume that the bees do not mind a little alcohol with their lunch). Each flower produces 1 to 4 seeds (‘nutlets’).
The arrangement of anthers and pistils in the two types of flower. See also item h in Sturm’s painting at the head of this article. The drawings are extracted from Meeus S et al. (2013) Biological flora of the British Isles: Pulmonaria officinalis. Journal of Ecology 101, 1353-1368.
Seed dispersal is enhanced by ants. The seeds have ‘tasty’ attachments called ‘elaiosomes’ which are richer in nutrients than the seed itself, with higher concentrations of amino acids, sugars, organic acids and polyols. The ants carry the seeds away to their nests, where the larvae may feast on the elaiosomes and then take the seeds to their waste disposal area where a proportion of the seeds will germinate to form seedlings far enough away from the parent plant to avoid competition.
Distribution of Pulmonaria officinalis in Britain and Ireland. There is evidence here of a general decline. Note also its near-absence in Ireland. From BSBI/Maps
In an earlier blog (on the Green Alkanet) we commented that the Boraginaceae is the plant family with all the best English common names. Pulmonaria officinalis has been called Spotted Dog, Soldiers and Sailors, and Our Lady’s Milk Drops (suggesting drops of the Virgin’s milk on the leaves). Perhaps the multiplicity of names in the Boraginaceae reflects the traditional use of its plants in herbal medicine. Children would have been taught to recognise and collect medicinal plants and cute names were memorable. But Pulmonaria officinalis does not have a strong reputation in herbal medicine. When I searched herbal medicines using google, I found lungwort leaves are sold for making a herbal tea, as a herbal food supplement2 and as an ingredient in homeopathy. I was surprised to learn that it is one of the (many) plants used to flavour vermouth.
There are other pulmonarias. Some have lost their spots. You may see some of them as garden plants. Here’s a gallery with notes:
The native Suffolk Lungwort, P. obscura with unspotted dark-green leaves. It’s hard to find in Britain, unless you live in Suffolk. This plant grows on poorly drained fertile soil of ancient woodland with a history of coppicing. Some people have considered it as merely a subspecies of P. officinalis. I saw adverts for it from the Royal Horticultural Society, but theirs has spotted leaves (the spots are small). I suspect hybridisation has occurred.
Red Lungwort, P. rubra. Image: Chris Jeffree
Red Lungwort, P. rubra, is a red-flowered introduced species often grown in gardens and sometimes found in the wild as an escapee. Like the Suffolk species, it lacks spots. The distribution in Britain tends to be northern, with most records between Edinburgh and Livingstone; there are several records from the North-east and only one from the Glasgow area.
Red Lungwort, P. rubra. Image: Chris Jeffree
Mawson’s Lungwort Pulmonaria angustifolia ‘Mawson’, a very attractive, blue-flowered lungwort without spots (but some authorities say otherwise regarding spotiness), often planted in woodland gardens. It has been called ‘blue cowslip’ as its flowers ‘look down’ like cowslip’s, but that feature is not peculiar to this species. Mawson was the famous polar explorer Sir Douglas Mawson, but I cannot find out why his name was borrowed.
Mawson’s Lungwort Pulmonaria angustifolia ‘Mawson’. Image: Chris Jeffree
The native Narrow-leaved Lungwort Pulmonaria longifolia, is found in Dorset, Hampshire and the Isle of Wight. There have been a few sightings in Scotland, but not recently. This one has lance-shaped leaves, from which it takes the name ‘narrow-leaved’. I have never seen it, but readers from Hampshire should know it well.
Narrow-leaved Lungwort Pulmonaria longifolia
Bethlehem Lungwort, Pulmonaria saccharata, also has lance-shaped spotted leaves, recorded in the south of England, but more common in the eastern parts of the USA and Europe. Strangely, there are a few records on the Isle of Skye.
Bethlehem Lungwort, Pulmonaria saccharata. Image: Chris Jeffree
There are as many as 18 species of Pulmonaria world-wide, and telling them apart is a challenge. It seems there are hybrids too, and attempts to understand how they arose from common ancestors have been made (see Meeus et al. 2013). Most have the common characteristics: they are perennials with overwintering rhizomes, they spread rather slowly (i.e. not invasive), their flowers start red and become bluish, they are hairy. They make good garden plants, regarded by horticulturists as well-behaved, slow-spreading and bee-friendly.
I am left puzzled about the spots. Someone needs to do some research on the gas concentrations under them1. If gas pockets are such a good idea from an evolutionary point of view, why have they not developed in other plant families?
Notes
1 The white spots are where the epidermis is detached from the mesophyll and there is an air pocket. I have been unable to find published work on their function. My speculation: it’s to recycle CO2 – respired nightime CO2 builds up during the night in these pockets, and is recycled in the day when photosynthesis begins.
2 Here is a quote from Plants for a Future: “They can be added to salads or used as a potherb. A fairly bland flavour but the leaves are low in fibre and make an acceptable addition to mixed salads, though their mucilaginous and slightly hairy texture make them less acceptable when eaten on their own. The young leaves make a palatable cooked vegetable, though we have found the texture to be somewhat slimy”.
3 The attribution for the image at the head of this article is: Hectonichus, CC BY-SA 3.0 https://creativecommons.org/licenses/by-sa/3.0, via Wikimedia Commons
References consulted
Birkinshaw CR and Sanford MN (1996). Pulmonaria obscura in Suffolk Watsonia, 21, 169–178.
Brys R and Jacquemyn H (2010) Floral display size and spatial distribution of potential mates affect pollen deposition and female reproductive success in distylous Pulmonaria officinalis (Boraginaceae). Plant Biology 12, 597-603.
Darwin CR (1862). On the two forms, or dimorphic condition, in the species of Primula, and on their remarkable sexual relations. [Read 21 November 1861] Journal of the Proceedings of the Linnean Society of London (Botany) 6: 77-96. http://darwin-online.org.uk/converted/published/1862_primula_F1717.html
Gaberščik A et al. (2001) The influence of enhanced UV-B radiation on the spring geophyte Pulmonaria officinalis. Plant Ecology 154, 49-56.
Konečná M et al (2018). Tasty rewards for ants: differences in elaiosome and seed metabolite profiles are consistent across species and reflect taxonomic relatedness Oecologia 188, 753–764.
Meeus S et al. (2013) Biological flora of the British Isles: Pulmonaria officinalis. Journal of Ecology 101, no. 5 (2013): 1353-1368.
©John Grace
