Yellow Loosestrife, Lysimachia vulgaris, at Redgrave and Lopham Fen.
In mid July our friend Sarah drove us to Redgrave and Lopham Fen, rightly described as “the largest valley fen in England and one of the most important wetlands in Europe.” It is a Suffolk Wildlife Trust reserve, straddling the upper reaches of the River Waveney, which forms the border between Norfolk and Suffolk (note 1).
Yellow Loosestrife, Lysimachia vulgaris, was just coming into flower, forming patches of bright yellow amongst the reeds, in contrast to the pale lilac flowers of Creeping Thistles, Cirsium arvense, growing beside the path.
Yellow Loosestrife (or Yellow-loosestrife) is a characteristic perennial plant of river banks, stream sides, marshes, fens and the edges of ponds and ditches. It is widespread in lowland Britain and Ireland where these conditions occur. It can be lost if wet places are drained or ditches are cleared but it can also colonise suitable new sites, possibly assisted by waterfowl (note 2). It grows to 1.5 metres (five feet) tall, with branching stems topped with clusters of attractive yellow flowers. Outside the British Isles, Lysimachia vulgaris is a native in many European countries, westwards into Asia and in Algeria in North Africa. It has been introduced into parts of North America and parts of New Zealand.
Along with the Cowslip (Primula veris) and Primrose (Primula vulgaris), which I’ve already written about, Yellow Loosestrife is a member of the Primulaceae, the Primrose family. Stace’s Flora lists eleven species of Lysimachia in the British Isles (note 3). Lysimachia is named after Lysimachus, a king of Sicily, who is said to have fed a member of the genus to an angry bull to pacify it (note 4). Vulgaris means common. The English name “loosestrife” is shared with another waterside plant, Purple Loosestrife, Lythrum salicaria (family Lythraceae), but this isn’t a close relative (note 5).
Cowslips and Primroses flower in spring, but Yellow Loosestrife flowers much later, in July and August. (See The Wildflower Finder and First Nature websites for some excellent photographs of the plant in full flower.)
The genus Lysimachia is interesting because around 40% of the species, including Lysimachia vulgaris, have evolved to produce floral oils, rather than nectar, as a reward for visiting bees (note 6).
Floral oils are mostly made up of long-chain acetoxy-substituted free fatty acids and have the consistency of olive oil. They are secreted by special thin-walled glands on the stamen tubes and the inner, lower surface of the petals, known as trichome elaiophores. Floral oils are often scented: in a 2007 study by thirty-six compounds were detected in scent samples from Lysimachia punctata.
Floral oil production is found in some 1,500 to 1,800 species of flowering plants worldwide, in at least 11 plant families, and is thought to have arisen as many as 28 separate times. Bees benefit from floral oils in two ways: they have a higher energy content than nectar or pollen and, as well as being used to feed the bee’s larvae, they are used to make a waterproof brood cell lining. (The adult bees don’t feed on the oils.) The oils are costly for plants to produce but this is worthwhile if the associated bee pollinates the flowers (note 7).
In England south of a line between The Wash and the Bristol Channel, Yellow Loosestrife’s flowers are attended by the solitary bee Macropis europaea, the Yellow-loosestrife Bee. The female bees have special projections on their basitarsi (the the basal segment of the tarsus) for collecting Yellow Loosestrife’s floral oils.
Yellow-loosestrife Bees were in attendance at Redgrave & Lopham Fen – both males swarming around the plants in search of females and females hard at work gathering pollen and floral oils. (The bees also visit plants such as Creeping Thistle and Water Mint for nectar.)
Yellow-loosestrife Bees nest in the soil, generally in banks or slopes. Nest sites are often at risk of flooding but the developing larvae and pupae are protected underground by a waterproof cell lining made from the floral oils. In Surrey, David Baldock found a Macropis europaea nest site at least 300 metres away from the nearest Yellow Loosestrife, and when he planted a single plant of Yellow Loosestrife in his garden pond, a male Macropis europaea visited within a week, even though he knew of no nesting sites or even Yellow Loosestrife within two miles of his garden (note 8).
A female Yellow-loosestrife Bee (Macropis europaea) at work in a Yellow Loosestrife flower.
Yellow Loosestrife has a number of potential medicinal uses, listed on the Plants for a Futrue website, including “a serviceable mouthwash for treating sore gums and mouth ulcers”, to treat gastro-intestinal conditions such as diarrhoea and dysentery, to stop internal and external bleeding and to cleanse wounds. A yellow dye can be made from the flowers and a brown dye from the rhizomes. The plant has also been burnt in houses in order to repel or remove gnats and flies. The plant is described as astringent but a subspecies (Lysimachia vulgaris davurica) is grown in China for food.
As well as Redgrave & Lopham Fen, Yellow Loosestrife and its bee occur at other sites in Norfolk, including many of the Broads and at Strumpshaw Fen RSPB Reserve and on Beeston Common, near Sheringham.
If you want to grow Yellow Loosestrife, Emorsgate Seeds sell the seeds, which can be sown at any time of year. Grow it somewhere damp in a clay soil in sun or semi-shade and it should do well. If you live in the south you could even attract its attendant bee.
Notes
Note 1 – We were able to visit the northern half of the reserve (Lopham Fen) without needing our passports, as it lies in Norfolk. We had mainly gone to see invertebrates, including another attempt to see the Fen Raft Spider, Dolomedes plantarius
On previous trips to Redgrave & Lopham Fen in 2018 (including one by train from Norwich to Diss followed by a taxi ride), we failed in our quest, as the pools where the spider lives had mostly dried out. We finally found an immature specimen at Carlton Marshes, another Suffolk Wildlife Trust reserve near Lowestoft, in September 2019.
This year there was plenty of water and we managed to see two Fen Raft Spiders, one of which is pictured below.
Fen Raft Spider, Dolomedes plantarius
Note 2 – The UK Wildflowers website gives an example of Yellow Loosestrife being outcompeted by Common Reed (Phragmites australis) at Hatchmere Lake in Cheshire. Regular cutting of reed, as at Redgrave & Lopham Fen, will presumably assist Yellow Loosestrife by keeping the reed bed more open.
Note 3 – Fourth Edition, 2019. Several are introductions, including the frequent garden throwout Dotted Loosestrife, Lysimachia punctata.
Other species of Lysimachia that I encounter in Norfolk are Bog Pimpernel (L. tenella, pink flowers, boggy, peaty ground), Scarlet Pimpernel (L. arvensis, scarlet flowers, a “weed” of arable land and gardens), Creeping Jenny (L. nummularia, damp places but surviving in shade in our back garden) and Yellow Pimpernel (L. nemorum, in woods. It “creeps” like Creeping Jenny but the leaves are more pointed).
I grow a form of Fringed Loosestrife, Lysimachia ciliata ‘Firecracker’, in the garden. It is far too dry for it on my sandy soil with minimal rainfall, even in semi-shade. I have to water it regularly in summer, but I like its contrasting purple leaves and bright yellow flowers.
When I first learnt plant names, Bog Pimpernel and Scarlet Pimpernel were both in the genus Anagallis.
Note 4 – Lysimachus means “scattering the battle” in Greek, and Wikipedia mentions several people of that name. To add to the confusion, one of them even founded a Greek city called Lysimachia (now in modern Turkey) and the First Nature website says that the plant was named after him, rather than the Sicilian king.
Note 5 – According to Merriam-Webster, “loosestrife” is intended as translation of Greek lysimacheios loosestrife (as if from lysis act of loosing + machesthai to fight).
Note 6 – Schäffler, F. Balao,and S. Dötterl studied a number of Lysimachia species and Table 1 in their paper lists which species produce floral oils. Lysimachia vulgaris produces them, as do L. punctata, L.ciliata, L. nummularia and L. nemorum. L. arvensis, and L. nemorum don’t.
Note 7 – Much of my information on floral oils and bees comes from Bryan N. Danforth, Robert L. Minckley and John L. Neff’s superb book “The Solitary Bees – Biology, Evolution, Conservation” (Princeton University Press, 2019), particularly pages 177 – 186.
Worldwide, 440 species of bee have become morphologically and behaviourally specialised upon oil-producing host plants.
Other plant families with species that produce floral oils include the Orchidaceae, Plantaginaceae, Scrophulariaceae, Cucurbitaceae and Iridaceae.
Note 8 – I highly recommend the late, great David Baldock’s book “Bees of Surrey” (Surrey Wildlife Trust, 2008).
