Rare Plants

I have been reading Rare Plants by Peter Marren, the latest (no 14) in the ‘British Wildlife Collection’. What struck me was how few I’ve seen of the book’s rare plants within the UK, but how many were familiar from holidays overseas.

In a way this isn’t surprising: geography dictates that the UK is on the edge of the range for many species. It’s also a reminder that when searching for an identification of a plant overseas, sometimes the answer may be within a UK field guide. This blog describes just a few of the plants written about in Rare Plants, along with encounters of them on Honeyguide wildlife holidays.

Strapwort Corrigiola litoralis in Extremadura.

Strapwort Corrigiola litoralis, a rather obscure member of the pink family, is in a list of 35 Critically Endangered native plants. It is found, in the UK, only at Slapton Ley on the south Devon coast, where it is dependent on disturbed patches of bare gravel. Being dependent on disturbed ground is a theme that crops up for several rare or scarce species – for example, all those dependent on arable habitats. This reminded me of finding and puzzling over this species in Extremadura in March, at first an unknown flower growing on disturbed ground by tracks or quiet roads on the plains. I couldn’t find an ID in Iberian references, and found the flower instead in the Fitter, Fitter & Blamey that I use at home. Strapwort is on Honeyguide’s Extremadura flowers web page, for flowers we see here — mostly on our March holidays – that are tricky to find in field guides. More recently we found strapwort at Castro Verde in Alentejo, Portugal, in November 2023.

Goldilocks aster, an autumn-flowering species.

There is a photo in the Rare Plants book of goldilocks aster Aster or Galatella linosyris on Berry Head, Devon, described as one of several natural rarities from limestone headlands on the west coast. This was another that prompted a ‘I know that flower’ thought. Most recently it was pictured in our Spanish Pyrenees holiday report from October 2024. This curiosity always looks a bit scruffy: the same could be said of the photo above from La Brenne, France in September 2023.

Field eryngo. Left with Graphosoma italicum; right at Castang.

Field eryngo Eryngium campestris is so commonplace in much of Europe that it’s a surprise to read that this flower is also on the Critically Endangered list for the UK. The Botanical Society of Britain and Ireland (BSBI) says “In Britain E. campestre is currently considered to be an archaeophyte [an introduced species in ancient times] but it has been thought to be possibly native in Kent and Devon.” Predominantly southern in distribution, one wonders if this species may become more common as the climate changes. The photo reminds us of good times at Castang in the Dordogne, where field eryngo is common.

Sea daffodil, Tarifa, 8 September.

A sprinkle of records in recent decades of sea daffodil Pancratium maritimum in south-west England might also be put down to climate change, though the current thinking is that these are either deliberately released or naturalised from gardens. Though autumn-flowering, we see masses of leaves and a liberal sprinkling of seeds of sea daffodils on the beach at Plakias, Crete, every spring (and Menorca, and just about every Mediterranean beach). It is pollinated by long-tongued hawkmoths, which might be a constraint to its spread.

LImestone woundwort and St Dabeoc's heath, both from Picos de Europa.

Two flowers have a connection to our Picos de Europa holiday. I remember looking at limestone woundwort Stachys alpina in the Picos and thinking that – as a British species – I really ought to know this. Delve a little deeper and in the UK it’s only found in one place in the Cotswolds and in Denbighshire (a good excuse for not knowing it from ‘home’) and its status – native or otherwise – is uncertain.

St Dabeoc’s heath Daboecia cantabrica has been known from Ireland for several centuries. With that scientific name, it’s no surprise that we find it in the Picos de Europa. Recent research, published in British Wildlife, has shown that the strawberry tree Arbutus unedo, once thought to be native to a few places in western Ireland, could well be an archaeophyte, brought in by ship-borne traders as long ago as around 1500BC. Might St Dabeoc’s heath have arrived in a similar way?

Tongue orchid Serapias lingua, Dordogne.

Not surprisingly, Rare Plants features several orchids, such as those with just a foothold in the UK. Examples include the critically endangered red helleborine, military orchid and monkey orchid. However, it was the accounts of tongue orchids that caught my eye, previously entirely absent from the Uk, yet three species have been discovered in Britain during the last few years. The first was small-flowered tongue-orchid Serapias parviflora, first seen in 1989. The book has a photo of a typical ‘swarm’ of the (or greater) tongue-orchid Serapias lingua in a field near Tiptree, Essex, in 2017. Long-lipped tongue-orchid Serapias vomeraceae was found in Kent in 2020. The consensus seems to be that these occurrences are natural and wind-assisted. What next? Perhaps sawfly or woodcock orchid?

You’ll see that the cover picture of the Rare Plants book is lady’s slipper orchid. This has a long and complicated history in the UK, too long to summarise here, and it is well-known for being exceptionally rare as well as being as glamorous as they come. I’ll simply note here that they are a feature of wonderful wood-meadows in Estonia.

Rare Plants (here on NHBS).

Chris Durdin