A few years ago my wife and I were hunting for sloes to make sloe gin for Christmas. We were in Glenluce in the SW of Scotland, where we found a particularly sloe-rich hedgerow. We noted the nearby ruins of Glenluce Abbey, a Cistercian monastery and wondered if these better-than-usual sloes had been cultivated by the monks hundreds of years ago. With our basket brimming, we wandered over to the Abbey. What impressed us more than the Abbey itself was the vegetation on its walls, but we were too late in the year to identify the brown withered remains of the dominant species. We returned the following May and found masses of a tiny purple-flowered plant that turned out to be the Fairy Foxglove, Erinus alpinus. I hadn’t seen it before, but it wasn’t difficult to identify.
Erinus alpinus, the Fairy Foxglove, also called Alpine Balsam and Starflower. Here is a single individual showing the structure of the plant. It is a perennial, living for about 5 years, 5-20 cm tall, leaves about 1.5 cm, the lower forming a rosette. Sometimes quite hairy. Family: Plantaginaceae (the Plantain Family) but older books put it in the Scrophulariaceae. Flowering time is spring and early summer. Photo: Richard Milne.
I’ve seen it many times since. It likes to grow on old walls where it roots in the lime-rich mortar. I’ve seen it on the walls of castles, walled gardens, many times in cemeteries and sometimes on old bridges. It is an alpine plant (some authorities say ‘subalpine’) and native to Algeria, Austria, Balearic Islands, France, Italy, Morocco, Sardinia and Switzerland. It was thought to have survived the Pleistocene glaciation in southern French refugia and to have postglacially immigrated to its northern Alpine location. It is also known from nunataks in the northern Prealps. But it didn’t make it to the British Isles until humans gave it a hand.
E. alpinus growing en masse at East Linton, East Lothian. In this image you can just see that the flowers are not entirely symmetrical (somewhat zygomorphic). Note also the hairy stems. Photo: Chris Jeffree.
It was introduced to Britain via the horticultural trade in 1739 but, as with many aliens, it took a while to ‘escape’, being first recorded in the wild in 1867. Famously, it has been recorded at the village of Wall, associated with Hadrian’s Wall, leading to the romanticised view that the plant came on the boots of Roman centurions, having been accidentally picked up during their long march across the Pyrenees en route to Britain. Like most really good stories this is almost certainly untrue, in fact a sort of Fairy Story.
E. alpinus growing on an old wall with Asplenium trichomanes at Lamlash on the Isle of Arran, May 2022. Photo: Chris Jeffree.
It seems to be expanding its range, although some of the increased records in recent decades may reflect an increased recording effort. It has especially increased in parts of Scotland and more generally in Ireland. I decided to check some of the areas in detail, picking places that are known to be very well-recorded. In Midlothian it wasn’t recorded until 1998. Even now there are only 13 records: its locations include the Edinburgh Castle, Inveresk and Penicuik. Another well-recorded area is Lanarkshire. There it was first recorded in 1975 but most of the records are from 2005 onwards and include six from Glasgow City and two from Lanark. Moving to Ireland, for County Clare I saw 20 records, most since 1997. It does, by the way, grow on the botanically-rich limestone of the Burren.
One of its favourite habitats – the stonework of cemeteries – pictured here in the West of Scotland. Photo: John Grace.
My survey of the records from well-recorded locations show that this little plant has steadily increased its range, and does not mind the urban environment. It seems to grow anywhere that has a lime-rich substrate. It does not grow at Ben Lawers, Scotland’s most famous site for arctic-alpine species, presumably because it simply hasn’t reached there yet. It has travelled far north, as the images from Sutherland show. This site (Invernaver, below) is probably its northern limit in the British Isles.
A more open situation at the site of a broch at Invernaver in Sutherland. E. alpina grows here on a steep, rocky, exposed south-facing, slope close to the broch. The substrate is shell sand. Photos: Chris Jeffree.
Some people think they are giving nature a helping hand by transplanting species. Of course, they shouldn’t do this, and these days it is a criminal offence. Mabey and Evans (1980) say that ‘many colonies’ of Erinus alpinus were created by a ‘married couple who carry a stock of seeds with them on their travels round Britain, planting them out on any suitable limestone site’. At some time in the mid-20th century, many montane species, were introduced by persons unknown to two limestone ridges east of Inchnadamph, which has earned the name Inchnadamph ‘Zoo’. A good recent description of the ‘Zoo’ is from the Assynt and Lochbroom Field Clubs- you can see it here.
What of its future? I think it will continue to increase its range and perhaps become a regular member of the urban flora, decorating ancient walls alongside the several other attractive aliens. What’s not to like about it? Some folk lug the plants from their walls whilst buying expensive alpines from their local nursery to stock their rockeries. There is a general fear that the weak acids secreted by plant roots will dissolve the limestone mortar, ultimately leading to the wall’s collapse but here is what English Heritage has to say on this contentious subject:
“….small flowering plants like Rue-leaved saxifrage (Saxifraga tridactylites) with its reddish, threelobed leaves, the nationally scarce Wall bedstraw (Galium parisiense) and common Whitlowgrass (Erophila verna) which flowers early in the spring. … These species are extremely unlikely to cause damage to
any built structure and should be left alone unless there are particular reasons for removal. Although
they often grow in cracks they are merely exploiting an opportunity and do not cause cracks in the first
place or grow in such a way that will make them worse”.
Rare white form spotted at East Linton in East Lothian. Photo: Chris Jeffree.
There are about 50 internet sites offering seeds and/or young plants, with descriptors such as ‘gorgeous little plants’ to lure gardeners to buy. Also the species has a Merit Award from the Royal Horticultural Society. Historically, the unregulated horticultural trade and the landowners of large estates played their part in the dispersal of alien species. What is different today is the intensity of this trading – the click of a button is all that anyone needs to procure a packet of seeds. A fairly recent and forward-thinking review of this topic by van Kleunen et al. (2018) suggest this
“… socio-economical, technological, and environmental changes will lead to novel patterns of plant introductions and invasion opportunities for the species that are already cultivated. We describe the role that horticulture could play in mediating these changes. We identify current research challenges, and call for more research efforts on the past and current role of horticulture in plant invasions. This is required to develop science-based regulatory frameworks to prevent further plant invasions”.
Erinus alpinus, distribution in the British Isles. On the left: before 1986; on the right: after 1986. From BSBI Maps.
However, Fairy Foxglove is one of the most benign of alien species. I like it, not just for aesthetic considerations but because it is an excellent example of how a montane species can find a niche and expand its range in the urban landscape.
European distribution, from GBIF. There are also a few records in North America, none elsewhere.
References
van Kleunen M et al. (2018) The changing role of ornamental horticulture in alien plant invasions Biological Reviews, doi: 10.1111/brv.12402.
Mabey R and Evans A (1980) The Flowering of Britain. Hutchinson, London.
©John Grace
Botany in Scotland 