Pulmonaria obscura

Pulmonaria are one of those old fashioned garden perennials that seem to be once again gaining popularity. Cultivars and species are popular with gardeners, they are perfect perennials for a semi shady garden and are one of the first perennials to emerge and bloom in spring.
Pulmonaria is a member of the borage family, and considering its early flowering time is always able to attract an abundance of appreciative bees.

Pulmonaria obscura is a rare species, more commonly found in parts of northern Europe, in the UK it is extremely rare. Formerly known as Pulmonaria officinalis ssp. obscura and commonly known as Suffolk Lungwort it is classed as ‘Endangered’. This plant is known from just three small locations in adjacent ancient Suffolk woodlands. It covers a total area of 18 square metres and has only 600 individual stands.
Formerly Pulmonaria obscura has been considered a variety or subspecies of P. officinalis and has the synonym of Pulmonaria officinalis ssp. obscura. However, now, on the basis of the sterility of hybrids between the two taxa , its specific status is generally accepted.

The flower stems of Pulmonaria obscura rise above the foliage up to 30cm (12in) tall and produce clusters of downward nodding bells that are notched and flared. The newly opened flowers are light red, changing later to purple and finally virtually blue at maturity, usually appearing in late March to early April they last for a few weeks. While many varieties have marked foliage from where they get the common name of ‘Spotted Dog’, one of the distinctions of Pulmonaria obscura is the lack of, or only faint markings on the foliage. It goes by the wonderful name of ‘Un-Spotted Dog’.

Pulmonaria prefer light to medium shade, with dappled or morning sun, so under deciduous trees is ideal, but they will generally adapt to full sun in cooler regions as long as consistent moisture is provided. Ideally they should be planted in moist, well drained, enriched soil, but they can adapt to slightly dry and average soil. It is a very tough plant, hardy and adaptable, even nightly spring frosts don’t seem to affect it.
Perfect for semi shady spots, used as an underplanting or groundcover it is an excellent choice for the front of a shady border. They are beautiful when combined with other shade lovers such as wild Primroses and Hosta. They can be grown under large clumps of plants such as Day lilies and Peonies and look outstanding in large drifts mixed with ferns and Astilbe. Mass plantings are eye caching and individual plants will over a few years grow into large clumps.

The Suffolk Woods:
Pulmonaria obscura is known from just three small locations in adjacent ancient Suffolk woodlands. Burgate Wood, Stubbing's Wood and Gittin Wood are within 1 km of each other. It covers a total area of 18 square metres and has only 600 individual stands.
A population of lungwort has been known at Burgate Wood in East Suffolk since 1842. Burgate Wood is a site of special scientific interest but the other two sites have no legal protection although they are on the register of county wildlife sites. Pulmonaria obscura is included in the third edition of the British red data book for vascular plants and is classed as ‘Endangered’,
There is no public access to Burgate Wood, Stubbing's Wood or Gittin Wood and permission to enter must be obtained from the owners in order to visit. However, plants of Pulmonaria obscura originating from Burgate Wood can be seen in Cambridge University Botanic Garden.

Burgate Wood in Suffolk is still thick with commons and greens, ancient lanes and woods, the elements of the pre-Enclosure landscape which have somehow survived in this part of the county. Two centuries ago, the Enclosures impacted on the old landscape by dismembering commons and open field systems. Burgate still has its Medieval wood, complete with original bank and ditch, 'giant coppiced stools' and the earthworks of a lost moated manor. The diversity of the plant life in this landscape is a measure of how long such traditional features have existed.
Burgate Wood is a Site of Special Scientific Interest SSSI. Its 75 acres are particularly good example of the type of oak-hornbeam woodland characteristic of this part of north Suffolk
The ground flora is diverse and includes several species that are indicators of ancient woodland, including one rarity. The ground flora contains much Dog's Mercury (Mercurialis perennis) with frequent Primrose (Primula vulgaris), Enchanter's Nightshade (Circaea lutetiana), Sanicle (Sanicula europaea) and Water Avens (Geum rivale). A number of uncommon species are present including Herb Paris (Paris quadrifolia), Yellow Archangel (Lamiastrum galeobdolon), Hairy Woodrush (Luzula pilosa) and the rare Lungwort (Pulmonaria obscura).
The wood contains a mysterious set of earthworks which are a Scheduled Ancient Monument No: 30571. They have been associated finds of pottery dated as Late Saxon to Medieval - 1001 AD to 1154 AD.

Sowing: Sow seeds in spring or in autumn.
Pulmonaria seeds need a period of cold to enable them to germinate. In autumn sow the seeds on the surface of seed compost, cover with grit and keep in a shaded cold-frame or cool glasshouse.
Sow seed 2.5cm (1in) apart in trays or cells containing seed compost. Sow the seeds on the surface of the compost, and place in a light position at a regular temperature of around 16°C (60°F) Germination should take place between 30 and 60 days at temperatures of around 15 to 18°C (60 to 65°F).

The seeds can also be sown during warmer times of the year, but it would be necessary to artificially simulate winter using the following method of 'stratification':
Place the seeds between two pieces of damp filter paper or folded kitchen roll then put into a polythene bag and place this into the fridge at 4°C (39°F) which is the temperature that most fridges are set at. Inspect the seeds after two weeks and remove as the seedlings appear, plant them in single small pots or trays and returning the ungerminated seeds to the fridge. Germination can be erratic, although most should germinate in 2 to 4 weeks.
When seedlings have their first pair of true leaves and are large enough to handle, transplant into 7.5cm (3in) pots containing peaty compost to grow on. Before planting outdoors, gradually acclimatise to outdoor conditions for 10 to 15 days. Plant them in a humus-rich, moisture retentive soil and in partial shade. Plant them quite deep, so the top of the roots are 25mm (1in) below the soil level. Water until established. They will tolerate full sun if the soil remains moist at all times.

Position:
Pulmonaria prefer light to medium shade, sun exposure should be either dappled or morning sun, so under deciduous trees is ideal, but they will generally adapt to full sun in cooler regions as long as consistent moisture is provided, but shade in the hottest part of the day would be beneficial. Ideally they should be planted in moist, well drained, enriched soil, but they can adapt to slightly dry and average soil.
The spots are created by air pockets in the foliage that cools the underside of the leaves. One could assume that the more spots, the sun tolerant.
Amending your soil with compost or peat moss will improve the growth of Pulmonaria and improve moisture retention. If your soil remains wet, the foliage will deteriorate quickly and wet soil over winter may kill the plant. In hot humid climates, Pulmonaria will go dormant in midsummer, reappearing when the weather cools toward autumn.

Cultivation:
Pulmonaria like to grow in soil that is cool and moist, so they require regular watering and should be mulched in the spring. Top dress with composted manure and bone meal (if soil tends toward acid) as soon as flowering is complete, and twice more during the summer with a mild fertiliser such as fish emulsion.
The leaves remain quite fresh throughout the growing season unless subjected to prolonged sun and heat. Foliage that may look poor in midsummer heat can be cut back to the ground, and fresh foliage will be produced for the cooler days of late summer and autumn. In regions with mild winters the plant will often remain evergreen. If it does not die back, remove damaged or dead foliage to promote fresh spring growth.
Pulmonaria are fairly short lived plants, living at most 10 years under ideal conditions. If you divide the clumps every few years you will be able to maintain them in your garden by producing new young plants to replace expired ones. Divide congested plants in the spring in cooler areas or the autumn in warmer areas.

Medicinal Uses:
Pulmonaria has been cultivated for centuries as a medicinal herb. Following the Doctrine of Signatures, the ovate spotted leaves of some species were said to be representative of diseased lungs, so logically the plant must be for lung problems- or so it was thought in late medieval times.
The plant has been used since the Middle Ages to treat coughs and diseases of the chest, perhaps for its hard hairiness (expectorant effect). In fact it is useful in the treatment of chest diseases and asthma.

Seed Collecting:
If you are happy to take on custodianship of these plants, it would be a good thing to collect seeds after flowering. The seed is good sized, black, shiny and ripe in mid to late summer. After flowering, the stems lay on the ground, as new leaves are grown. Seed is not easy to collect, each flower might produce seed but only one seed per flower. As the seed nears the point of ripping it is very easily dislodged from the plant making it a rare find to collect ripe seeds from the old flowers. The use of some kind of drop cloth, like a handkerchief or cheese cloth might be helpful in collecting seed as they are dislodged. Place the drop cloth down around the plants three or four weeks before the seeds ripen and collect them as they fall out of the flowers onto the drop cloth. Seeds are best sown as soon as collected and given a period of freezing. They can be planted out in a pot to over winter or in a seedbed. Plants germinate in mid spring.

Plant Uses:
Shade and Woodland Gardens, Rock gardens, Containers, Underplanting

Origin:
There are well over a dozen species of Pulmonaria, but only a few commonly cultivated for garden use. In their native environments they grow on a wide range of soils from acid to alkaline, dry to wet, sunny to shady, along streams and in mountains.
Pulmonaria obscura grows in deciduous and coniferous mixed forests. It usually prefers poorly drained, nutrient-rich, and mostly calcareous soils. Its distribution ranges from central Sweden and southern Finland to Central Europe. In Austria, the species is very rare and endangered, while it is common in Northern Switzerland. In Britain it is quite rare, but its presence has been confirmed for Suffolk.
Pulmonaria obscura is sometimes grown in Finland as an ornamental, and in olden times it was used as a medicinal herb in the same fashion as its more southern relative, Pulmonaria officinalis. In Finland it is also called our Lady’s Milk Drops because of the pale white spots on its leaves.

Nomenclature:
The genus name comes from the Latin pulmoa meaning lung and was first used by Leonhart Fuchs (1501-1566), a German physician and one of the three founding fathers of botany. (The Greek word pneumōn meaning lung is where we get the English word pneumonia, a disease of the lungs).
The species name obscura simply means obscure. (dusky, indistinct or uncertain.)
It is a member of the Boraginaceae, the borage family.

Formerly Pulmonaria obscura has been considered a variety or subspecies of P. officinalis and has the synonym of Pulmonaria officinalis ssp. obscura. However, now, on the basis of the sterility of hybrids between the two taxa , its specific status is generally accepted.
When Linnaeus invented the binomial system of nomenclature, he gave the specific name 'officinalis' to plants (and sometimes animals) with an established medicinal, culinary, or other use. The word officinalis is derived from the Latin officina meaning a storeroom (of a monastery) for medicines and necessaries. It literally means 'of or belonging in an officina', and that it was officially recognised as a medicinal herb. It conjures up images of a storeroom where apothecaries and herbalists stored their herbs.

Colour Change in Flowers:
Pulmonaria obscura, the Suffolk lungwort flowers early in the spring in lush woods, where it competes with hepatica and wood anemone. Its newly opened flowers are light red, changing later to purple and finally virtually blue. The flower takes its colour from an anthocyanin which acts like a litmus test paper and changes colour as the cell fluid becomes more alkaline as the cells age.
Ecologists have spent a long time pondering why some flowers change colours as they age. Other flowers that grow change colour in the same way are, apart from the lungworts, comfrey (Symphytum officinale) and spring vetch (Lathyrus vernus).
The reason for the colour change is probably to do with pollination biology: only the freshest flowers have the nectar that the pollinators are interested in, but the older flowers add to the size of the inflorescence and make it look more impressive and thus play a part in attracting insects, even as they age. Considering its early flowering time, Pulmonaria attract an abundance of bees.
Pollinated flowers develop a dark schizocarp, whose carpel has a light-coloured appendage, an elaiosome, which attracts ants. As they eat it the ants transport the seeds to new growing places. By summer the flowering stem has withered away to nothing, but lungworts that are growing in sunny broad-leaved forests are easy to recognise too by their large, rough summer foliage.

Acknowledgments:
With acknowledgment to ‘Pulmonaria obscura Dumort. (Boraginaceae) in Suffolk’
The study of Pulmonaria obscura, published in 1996 by C. R. Birkinshaw and M. N. Sanford began when C. R. Birkinshaw was employed by the Nature Conservancy Council and based at Cambridge University Botanic Garden.
It was inspired and guided by Dr C. D. Pigott with the assistance of J. Free at Cambridge University Botanic Gardens.