Silene flos-cuculi – July 22nd 2024 – (Ragged Robin)
This is another species that changed its Latin name recently. Fortunately, the English name Ragged Robin has remained the same for at least two centuries. Most of us knew it as Lychnis flos-cuculi but now we must call it Silene flos-cuculi. We welcome it into Silene as one of the Campions.
The strange specific name flos-cuculi is unchanged: it means ‘flower of the cuckoo’ because the first flowers appear in early summer, when the cuckoo can be heard in Britain.
Illustration by Amédée Masclef, Public domain, via Wikimedia Commons. Amédée Masclef (9 August 1858 Béthune – 1916) was a French abbé and botanist best known for his three-volume 400-plate work ‘Atlas des plantes de France’
Ragged Robin belongs to the Caryophyllaceae, the Family of chickweeds, campions and carnations, and even to the untrained eye it does resemble the Pinks beloved of suburban gardeners. It has those slender stem-leaves in opposite and decussate pairs (nicely shown above, in Amédée Masclef’s illustration).
Ragged Robin flowers, 3-4 cm in diameter, each petal deeply-cleft to form four lobes. Note the pale-coloured coronal scales at the base of the petals. Image: Chris Jeffree.
It is a native perennial occurring in marshy places, including damp meadows, fens and open areas of wet woodlands. Its native status is proved from pollen found in archaeological excavations, for example at Bearsden in Scotland. It was once abundant throughout Britain but now it can be hard to find.
Rather strangely, Gerard does not describe it in his 1597 Herbal, but it crops up in Flora Londinensis published by William Curtis in six volumes between 1777 – 1798 . From his description (below) it was clearly very common around London when he was writing.
Description of Ragged Robin by William Curtis in his 18th Century Flora Londinensis, now available online thanks to the Smithsonian Libraries and Archives; downloaded from here
In Scotland, it was included in an early local Flora by Thomas Hopkins published in 1813 called Flora Glottiana: a catalogue of the indigenous plants on the banks of the River Clyde and in the neighbourhood of the City of Glasgow.
It is a beautiful plant with strikingly ragged flowers. Called ’ragged’ because of the petals, which are ‘deeply 4-cleft with narrow spreading segments’, and they become even more ragged after being battered by wind and rain. We saw its well-battered state on a recent trip to Fort William in the western Scottish Highlands, growing with rushes, sedges and buttercups quite close to the sea. In the database PLANTATT it is listed with a salt-tolerance of nil, but judging from the BSBI’s distribution map I think it must have at least some degree of salt tolerance.
Flower visited by the Eurasian bee chafer, Trichius fasciatus. Ragged Robin is a nectar-rich plant which is attractive to many large insects including bees, butterflies and hoverflies. Image: Chris Jeffree.
The flowers are pink, not red like the Robin of its English name, although we find quite wide variation from white to dark pink. It has become popular with gardeners: I found over 100 offers online (I gave up counting) some of them for the rare white variant and a few with double blooms. Ragged Robins are usually marketed as highly suitable for the margins of ponds.
Do the flowers smell? Andreas Jürgens investigated the chemical nature of the scent produced by ten species of Silene at the Botanical Garden of the University of Ulm in Germany. Air was collected from around the flowers, and then analysed for volatile organic molecules (Jürgens 2004). As many as 60 chemical compounds were identified. Ragged Robin had one of the most diverse perfumes, with 28 separate compounds. We humans have a poor sense of smell but insects are capable of smelling and differentiating between thousands of volatile compounds at very low concentrations, helping them to navigate to their preferred flowers.
I can’t smell Ragged Robin at all. To humans, many flowers do not smell but to insects most of them do.
The volatile compounds are dispersed into the air, assisted by the turbulent air flow around the flower itself. I wonder how important the floral structure of Ragged Robin might be in this process? As you can see in the images of flowers, Ragged Robin has peculiar scaley structures at the base of the petals. At first, I thought these were the nectaries but they are not. It took me a while to find any reference to these oddities. Greuter (1995) may have been the first person to give them a name. He calls them ‘coronal scales’ and uses them as an identification aid for the plant Family. But what is their function? My best guess is that they generate additional turbulence to speed up the diffusion of the volatiles that are so important for attracting pollinators.
Ragged Robin in dune slacks at Aberlady Bay, Midlothian. Image: Chris Jeffree.
Ragged Robin decreased in the UK during the second half of the 20th Century, as marshland and pasture were drained and turned into productive agriculture. In England, it is deemed to be ‘near-threatened’ because its habitat has declined. I looked for data on recent changes in wetland areas in Scotland. The UK’s National Office for Statistics has compiled many environmental data sets, some of them from the Centre for Ecology and Hydrology, and some from NatureScot. The data set for Scotland (see below) on the number of sites classed as ‘Fen, Marsh and Swamp’, is encouraging, showing improvements since 2007. However, these are simply ‘the number of sites’ in the survey, some of them are presumably very small The total areas in the survey may be tiny compared to the situation before the lowland landscape became dominated by industrialised agriculture and urban development.
The condition of Fen, Marsh and Swamp in Scotland, from the UK’s Office of National Statistics. More information is here.
Local Authorities like to sow native seed mixtures, aiming to create or restore species-rich plant communities. Commercial seed companies use colourful species, and so Ragged Robin is sometimes chosen for wetter sites. Such plantings are well-intentioned and although a meadow with all its diversity can never be truly restored, a good approximation is sometimes achieved. Researchers in Switzerland examined 26 populations of Ragged Robin, some of which were natural whilst others were introduced by sowing commercial seed mixtures (Aavik et al. 2012). They found the sown populations were genetically distinct from the native populations, and inbreeding was more common. The researchers concluded that seed should be collected from numerous individuals in large and non-isolated populations near to the restored sites.
A dense population of Ragged Robin. Image: Chris Jeffree.
Ragged Robin has a somewhat restricted range in the world as a whole, most records coming from its native Europe and western Asia. It reached North America around 1811, perhaps as an ornamental originally and later in ships’ ballast. It was naturalised in New Zealand by 1871.
British and global distribution of Ragged Robin. It is mostly a lowland species but in Britain it has been recorded to 750 metres above sea level at Cross Fell in Cumberland. Attribution: British from BSBI/maps and Global from GBIF
References
Aavik T et al. (2012) Genetic consequences of using seed mixtures in restoration: A case study of a wetland plant Lychnis flos-cuculi. Biological Conservation 145, 195-204. https://doi.org/10.1016/j.biocon.2011.11.004.
Greuter W (1995) Silene (Caryophyllaceae) in Greece: a subgeneric and sectional classification. Taxon 44: 543-581. 1995. – ISSN 0040-0262.
Jürgens A (2004) Flower scent composition in diurnal Silene species (Caryophyllaceae): phylogenetic constraints or adaption to flower visitors? Biochemical Systematics and Ecology, 32, 841-859. https://doi.org/10.1016/j.bse.2004.03.009.
Kolkman A et al. (2022) Sown wildflower strips offer promising long term results for butterfly conservation. Journal of Insect Conservation 26, 387–400. https://doi.org/10.1007/s10841-021-00347-2
Stroh PA et al. (2020) Silene flos-cuculi (L.) Clairv. in BSBI Online Plant Atlas 2020
Witt T et al. (2013). Data from: Nectar sugar composition of European Caryophylloideae (Caryophyllaceae) in relation to flower length, pollination biology and phylogeny [Dataset]. Dryad. https://doi.org/10.5061/dryad.7bc88
©John Grace
