Russian seeds frozen for 10 years are helping save a rare Scottish gem

Seeds collected from Russia around a decade ago and put to sleep in a deep freeze at Edinburgh’s Royal Botanic Garden (RBGE) have been gently revived, placed in a complex growing system involving a beer chiller, cascades of water and moss to replicate a Scottish peatbog, and nurtured into new plants.

It's now hoped that the plants which began life in a Russian bog can be transplanted to specially selected spots, helping to boost the fortunes of one of Scotland’s most fragile flowers.

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Once widespread, delicate marsh saxifrage has become so rare due to habitat loss and over-grazing that it is now only found at six sites in Scotland: two in Caithness, two in the Cairngorms and one each in the Monadhliath Hills, near Inverness, and the Pentland Hills near Edinburgh.

It has also dwindled in numbers right across Europe and is now a protected species, meaning harvesting seeds from other locations is no longer possible.

The Russian seeds were collected around a decade ago and frozen in a seed bank at the Inverleith garden’s laboratories.

Staff there recently defrosted some of the seeds and created a lab-version of a peat bog. It involves a beer chill cabinet at the heart of a construction which allows gentle cascades of water to filter through baskets filled with sphagnum moss.

A ‘cascade’ has been built to provide the precise requirements for growing marsh saxifrage (Image: RBGE)

Temperature and pH have been regularly monitored to ensure the life support system provides the ideal conditions needed for the tiny plants to sprout.

It’s now hoped that the first Russian marsh saxifrage will be planted next year, helping to both boost current numbers of the plant but also strengthen its genetic makeup to help future generations.

The work to secure the future of the tiny yellow flower is part of a major project aimed at helping ten ‘at risk’ plants, trees and a fern. 

As well as the Russian connection, staff from RBGE are preparing to travel to south west Norway in the coming months to learn more about why four other rare Scottish plants covered by the project manage to thrive so well there.

While there, they plan to harvest a collection of Norwegian seeds.

It’s hoped they can then produce new plants which, after stringent testing to ensure there is no biosecurity risk, can be planted in spots identified as similar to the locations in Norway where they are most abundant.

The plants they hope to grow from Norwegian sees, Alpine blue sowthistle, Whorled Solomon’s seal, Small cow-wheat and Oblong woodsia, have all slumped in numbers here due to the loss of their woodland habitat and over-grazing from deer and sheep.

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In the case of Alpine blue sowthistle, only four populations are known to survive naturally in the wild, however, they have retreated to high ledges and gullies on remote mountains in the eastern Cairngorms.

Their challenging location makes retrieving seeds extremely difficult.

Rare Whorled Solomon’s seal is restricted to nine small populations in Perthshire (Image: RBGE)

Whorled Solomon’s seal, with tall arching stems of vibrant green foliage and delicate white bell-like flowers, is now only found in nine spots within Tayside, and Small cow-wheat, which has pairs of golden-orange beak-like flowers running up its stem and prefers riverside woodlands, is now mainly found in the Cairngorms National Park.

While just a handful of populations of Oblong woodsia remain in the Aberfeldy area. Once abundant, it suffered serious declines during the Victorian era due to over-collection, to become known as the rarest fern in Britain. 

Dr Aline Finger, a conservation geneticist and molecular ecologist at RBGE involved in the project, said that while the four species thrive in Europe, they have become genetically weak and clinging to survival here.

“They are really rare in Scotland but widespread in other countries. One reason for that is we have lost the natural forest cover with that the species prefer.

"They end up in areas that are inaccessible to grazing animals but which is not necessarily their natural habitation – such as steep ledges or crevices in the Cairngorms.  

“Then, when we define habitat of that species, we say it loves steep ledges and crevices. Yet when we look abroad, they are growing in a completely different habitat.

“We can learn a lot about them by going to other countries where they are widespread, understanding why they grow there, and what the habitat is like. We can then return to Scotland to look for similar habitats here.”

The group plans to collect seeds from Norwegian sites for new plants to boost the Scottish stocks and inject new genes into the current mix, helping to become more resilient and boost future generations.

“When there is a lot of in-breeding with plants, their viability goes down, seed production is reduced, germination is lower and the survival of seedlings is lower," added Dr Finger.

Dr Aline Finger of RBGE collecting samples of Alpine blue sow thistle, a woodland plant that has now retreated to hard-to-reach locations (Image: RBGE)

“That with the habitat around them having changed means they have a very low chance to recover by themselves and we have a situation where there is a reliance on us doing a lot of intervention. That is very time consuming, costs a lot of money but there’s not much else we can do.”

Initial trials using Scottish Alpine blue sow thistle crossed with Scandinavian and Norwegian plants have already produced much healthier and stronger plants that survive longer in transplantation sites, she added.

It’s hoped that plants raised from Norwegian seeds can be nurtured in time for planting in 2024, at woodland and other locations identified as being geographically and climatically similar to those found in Norway.

While the Russian marsh saxifrage plants are also likely to be transplanted next year, at locations away from the remaining Scottish stock to ensure there is no negative impact on the existing wild population.

Much of the transplantation project using foreign seeds hinges the go-ahead from NatureScot and intense biosecurity checks to ensure there is no risk of importing new diseases into the Scottish landscape.

She added: “Our biosecurity team check the seeds and we are only able to use them when it absolutely clear to do so.”

The work is part of the three-year Scottish Plant Recovery project to restore ten threatened Scottish plant species. 

Oblong woodsia, a favourite for Victorian collectors, is now Britain's rarest fern (Image: RBGE)

Supported by the Nature Restoration Fund, involves five trees, four flowers and one fern, which will have their survival prospects improved by boosting both numbers and genetic diversity at carefully selected sites across Scotland.

They will include two types of “critically endangered” white beam trees found only in Arran, Wych elm - the only elm truly native to the UK which has been decimated by Dutch Elm Disease - and native crab apples, which have been threatened by hybridisation with cultivated apples.