Category: plants

Plant blindness

Posted on by andy.winfield

You may or may not of heard of the term ‘plant blindness’; it’s a phrase that we in the Botanic Garden have been hearing much more of in recent years and will continue to throw around in the future. It refers to the slow shutting off of plant knowledge from generation to generation resulting in an inability to acknowledge plants around us. The simple things that were once common knowledge, such as dock leaves used for nettle stings are becoming bred out of a collective instinct and plants are becoming irrelevant and annoying green things to many people.
I can remember when my eyes were truly opened. I noticed trees that I hadn’t before; as I walked along the street I started looking at the borders and the hanging foliage all around me. Before, I’m not sure what I looked out for in the streets, the pavement or the shops, who knows, but plants for sure changed my life and I see them changing the lives around me at the Botanic Garden. I think I could live to be three hundred and still find something in the plant world that fascinated me. This week I learnt about the incredible relationships between some species of orchid and ants. The ants don’t pollinate the orchid flower but hang around the plant living off an ‘extrafloral’ nectar secreted elsewhere; they then do everything to protect their food source and keep the plant safe. Plants and animals have these delicate relationships that allow both to flourish, and it’s fair to say that ours has become less delicate over the years.
Dandelion seed head
This change in the collective instinct of people has come about through successive generations becoming more urbanised with less plant interaction such as blowing a dandelion seed head, throwing a grass seed dart, eating wild blackberries or sticking cleavers to jumpers; children still do this but there are many who don’t and lose a connection with the plant world. The result of this is that education reduces the amount of plant learning, and in biology courses there is a main focus on the animal kingdom; there is a perceived lack of interest in the plant world. Things have become so bad that the Oxford Junior Dictionary removed words like ‘acorn’ and ‘buttercup’ preferring instead ‘broadband’ and ‘cut and paste’; they were seen as no longer relevant to a child’s life.
University of Bristol Botanic Garden
There is however, a great appetite among young people to be green, to recycle and mend the excesses of the generations that went before them; often students tell me it’s the biggest issue for them and they’d like to make a difference. How is a difference made? I think we can all make a simple difference by introducing plants to friends and relatives, opening eyes to the trees and weeds and the force of life going on around us and under our feet. It could be argued that many of the world’s problems can be solved with plants; forests, food, habitats are all areas that need experts, and while there are many graduates of zoology degrees there are few from plant sciences. This is changing with Universities now offering full plant science degrees; there are many jobs in plant sciences as governments and companies are beginning to see how important it is. Bristol University is launching a plant science degree starting in September 2019 based in the magnificent Life Sciences building with a group of world experts in the field of plant science. Of course, undergraduates will use the Botanic Garden as a second home and have access to all our knowledge and experience, we’re really looking forward to it. If you, a relative, son or daughter are interested click here to view the degree.
We all have a role to play in protecting our relationship with the natural world which can be played by simply talking about the plants we see to people. I’m always disposed to optimism and today’s

young people seem to be committed to green ways; this problem arose through successive generations and perhaps it can be cured in the same way, the passing down of knowledge as we go.

By Andy Winfield

The Svalbard Global Seed Vault: a safe haven for seed

Posted on by andy.winfield

By Helen Roberts

Svalbard is a group of Norwegian islands located in the high Arctic and only 1,300 km from the North Pole. It is breathtakingly beautiful. The landscape is stark, unforgiving and wholly memorable. I visited these islands more than 16 years ago as part of a 6-week science expedition – I was part of a botanical group looking at the exceptionally low-growing Arctic Willow. 
Memories of that place are still strong today. Its beauty and sense of isolation is unique. The humdrum of everyday life is simply stripped away here. You are left with the landscape, weather and incredible flora and fauna. Although life became simple, the vastness of the place was exhilarating and I felt totally and utterly free. 
The stark landscape of Svalbard
Photo credit: Paul Williams [via Flickr CC BY-NC 2.0]

The Arctic is an ideal refuge for seeds

Within this unforgiving landscape, nestled deep within a mountainside, is a seed bank of global importance. It holds 12,000 years of agricultural history and contains the world’s largest collection of crop diversity. 
The Global Seed Vault is the brainchild of renowned scientist Cary Fowler, a former executive director of the Global Crop Diversity Trust. It started as a simple idea back in the 1980s in the spirit of global collaboration, and finally came to fruition in 2008 when the building was completed. However, building the collection within is ongoing.
Svalbard Global Seed Vault
Photo credit: Amber Case [via Flickr CC BY-NC 2.0]
The facility currently holds about 850,000 different varieties of seed and acts as the back up for seed banks across the globe. This is a collection that is vastly important for food security and the safeguarding of crop diversity. Those 850,000 packets of seed represent more than 5,000 species and nearly half of the world’s most important food crops, from cereal and rice to unique varieties of legumes. The seed deposits come from over 60 different institutions and represent nearly every country in the world. 
The chosen location of the global seed vault is an interesting story. It needed to be located somewhere safe from both potential natural disasters and human conflict. Svalbard itself is a safe place to store seed both in terms of physical and social factors. Svalbard’s remoteness ensures an extra layer of security, while its geological stability and location, 130m above sea level, means the vault would be safe even in the worst-case scenario of sea-level rise. The storage facility is buried 150m deep into the side of a mountain where there is no radiation and where humidity levels remain low. The mountain also acts as a natural freezer, reducing the facility’s reliance on mechanical refrigeration. The local infrastructure on Svalbard is also very good despite its remoteness – Svalbard is serviced by regular scheduled flights.
Svalbard itself is also politically very stable and military activity is prohibited in the region under the terms of the Treaty of Svalbard of 1920. The local government is highly competent and Norway has long been recognised as a key country in the international efforts to conserve Plant Genetic Resources for Food and Agriculture (PGRFA). 

Building and running the vault

The Global Seed Vault is built to store up to 4.5 million different varieties of seed. Constructed to be highly functional, the rectangular edifice emerging from the side of the mountain is stark but architecturally beautiful. The structure is energy efficient; insulated by the mountainside, it maintains an ambient temperature of -7°C and therefore only needs a further temperature drop to -18°C to reach the recognised standard temperature for the storage of viable seed. 
The vault was built and paid for by the Norwegian government to provide a service to the world community. The structure took 12 months to build and cost NOK 50 million (approximately £4.6 million). The facility runs as a partnership between the Government of Norway, the Nordic Genetic Resource Centre (NordGen) and the Global Crop Diversity Trust. Operations regarding the vault are administered and controlled by an international advisory council of experts representing the Food and Agriculture Organization of the United Nations (FAO), national gene banks, the Consultative Group on Agricultural Research (CGIAR) and the Governing Body of the International Treaty on Plant Genetic Resources for Food and Agriculture (ITPGRFA). 

Inside the building

Some people are lucky enough to visit the seed vault on the rare occasions that you can gain access inside. I had to see the interior of the facility via a virtual tour. 
The front entrance is understated, although to gain access you have to go through half a dozen locked doors, each requiring a different key. Although, security appears minimal, it’s not. The facility is under constant surveillance by Staatsbygg, the government of Norway’s property manager and developer;  security cameras and sensors are located throughout the building. There is some natural security, of course, as the roaming polar bears outside outnumber the human population of Svalbard. 
From the entrance lobby, a 150m long tunnel extends into the mountain before reaching the three main storage chambers. At the moment, only one storage chamber is in use, in time the others will be filled as more seed varieties are deposited. 
Seed is only deposited three times a year and this is the only time when the vault is opened. 

Making a deposit

The metal shelves inside the Global Seed Vault.
Photo credit: Dag Terje Filip Endresen
[via Flickr CC BY-NC 2.0]
On arrival to Svalbard, seed lots are x-rayed and taken to the vault by NordGen staff members. The seed boxes containing the seed, which have been carefully placed in 3-ply aluminium packages, are then wheeled by trolley to the main storage chamber within the vault. Each package will contain on average 500 seeds. 
The seed lots are placed on simple metal shelving and are assigned bar codes to allow easy retrieval. They are catalogued using an information system called the Seed Portal of The Svalbard Seed Vault. This allows depositors to submit seed inventories and the general public to look at basic information about the seed that is stored within. Storage is free to depositors and they control access to the deposits. It is an International Black Box system, which ensures that only the depositor can access the raw seed and open the boxes. 

The most recent seed deposits

Last year, the first tree seeds were deposited from Norway and Finland. In February, pine and spruce seed was taken to the vault for storage from the Norwegian Forest Seed Center and the Finnish gene reserves forests of Lappträsk and Puolango, and Filpula and Lovisa. This deposit provides a back-up in the event that global climate change, forest management techniques and other factors, such as pests and disease begin to compromise the genetic diversity of these forests. It is a method of conserving the existing genetic resources and enabling long-term monitoring of the genetic variation within these forests, including any changes that occur because of tree breeding. This long-term tree seed project involves the countries of Finland, Denmark, Sweden, Iceland and Norway. 
The last deposit of seed was on 26th May 2016, with deposits from Germany, Thailand, New Zealand and the World Vegetable Center in Taiwan. Germany placed over 6,000 accessions into the vault of a number of different crop varieties, New Zealand deposited a number of varieties of sheep food including rye grass and white clover, Thailand deposited some 20 samples of very special chilli peppers and the World Vegetable Center deposited 1,200 seed lots from a number of different nations. 

Our agricultural future

The importance of this seed vault is apparent; it ensures the survival of the world’s most important crop species. Some seed varieties within the depths of this safe haven can survive for up to 4,000 years. In terms of food security, that is long term planning for human agriculture. 

Helen Roberts is a trained landscape architect with a background in plant sciences. She is a probationary member of the Garden Media Guild and a regular contributor to the University of Bristol Botanic Garden blog.


References:

Doomsday Vault Opened for Syrian Seeds: 
What is NordGen?:
Croptrust: 
Forest seed destined for Svalbard:
Forest tree seeds arrive at Svalbard’s ‘Doomsday vault’:
Arctic seed vault ‘key to future global crops’:
Storing the World’s Seeds in a Frozen Mountainside:
From sheep food to chili peppers – seed deposit at Arctic Vault takes the world one step closer to future food security: 
In the vault: David Osit:
Svaalbard Global Seed Vault:

Know your knotweed advice

Posted on by andy.winfield

By Nicola Temple

Researchers at the University of Exeter‘s Penryn campus have had a comprehensive look at Japanese knotweed (Fallopia japonica)  guidance from a range of sources on the web, including government sites, environmental NGOs, weed control companies, the media and the property market. They’ve found that this advice is often contradictory and even misleading.

A Japanese knotweed contaminated area in Hertfordshire
is identified with signage.
Photo credit: Peter O’Connor via Flickr [CC By-SA 2.0]
Japanese knotweed was introduced to the UK as an ornamental in the mid-1800s. It quickly became a problem plant, spreading swiftly and widely across the UK. This brutish invasive can penetrate building foundations and drains and is estimated to cost the UK economy £165 million a year.
The plant can grow from very small fragments of rhizome that weigh as little 0.01 g [1]. The rhizome material is capable of surviving for three months in a salty environment, which allows it to spread in coastal regions. Disturbing the rhizomes underground only promote growth and cutting the material above ground stimulates new above ground stems. It is the very definition of nuisance.

Japanese knotweed and the law

Two pieces of legislation were enacted to  provide the legal teeth needed to help control Japanese knotweed [2]. Under the Wildlife and Countryside Act 1981 (Section 14), it is illegal to plant or otherwise cause Japanese knotweed to grow in the wild. Offences can carry a maximum £5,000 fine or six months in prison, or both, in magistrates court. A Crown Court can impose an unlimited fine or maximum prison sentence of 2 years, or both.
The second piece of legislation is under the Environmental Protection Act 1990 (Section 33), where it is classed as ‘controlled waste# and must therefore be disposed of according to the Environmental Protection Act (Duty of Care) Regulations 1991. If you keep, treat or dispose of knotweed in a manner that is likely to allow it to spread, a magistrates court can impose a maximum fine of £20,000 or prison sentence of 6 months, or both. A Crown Court can impose an unlimited fine or maximum prison sentence of 2 years, or both.
Allowing Japanese knotweed to spread to your neighbours can also be considered a private nuisance. Failure to control this plant on your land could therefore result in a prosecution or community protection notice.

Mixed messages

Japanese knotweed growing along a fence in East London.
Photo credit: Gordon Joly via Flickr [CC licence BY-SA 2.0]

The research, published today (4th July) in the journal Applied Ecology, included a content analysis, which objectively describes written, spoken and visual communication, and allows researchers to quantify different types of content. This is a method often used in social research, but rarely applied to ecological questions, such as invasive plants. The results showed that there is conflicting advice out there, particularly about the disposal of Japanese knotweed, which could result in people taking the wrong course of action that leads to the unlawful and environmentally harmful spread of the plant.
“It is important to provide clear advice about the waste disposal of Japanese knotweed,” explained Beth Robinson, a PhD researcher in Exeter’s Environment and Sustainability Institute and lead author of the study, “as it can regrow from small fragments of rhizome and incorrect disposal of waste material can result in further spread of this plant.”
Even government websites were found to have conflicting and unclear information. The researchers point to Devon and Cornwall councils as both having valuable and accurate information about knotweed management. However, most of us are likely to consult the website of our own local council with the assumption that the information they provide is accurate.
“We recommend that local and national authorities collaborate and work towards disseminating more consistent messages,” said Robinson.
A tendency by the media to sensationalise the risks associated with this invasive plant can lead to unnecessary anxiety and expenditure.  An extreme example of this was headlines in 2013 such as ‘Murder andsuicide by husband driven mad over knotweed‘. Stories such as this make it sound as though the plant might have a psychoactive effect – driving people mad by its sheer presence, when indeed there are serious underlying mental health issues.
The Exeter researchers stress that Japanese knotweed needs to be dealt with on a case by case basis. While some knotweed invasions do require professional assistance, small-scale occurrences in domestic gardens may be effectively controlled and disposed of responsibly by the homeowner.

Visit the Cornwall Council website for some reliable information about Japanese knotweed and its management. 


The paper in Applied Ecology is titled ‘Weeds on the web: conflicting management advice about an invasive non-native plant’ and is authored by Beth S. Robinson, Richard Inger, Sarah L. Crowley and Kevin J. Gaston.


Sources:

[1]     Macfarlane, J.S. (2011) Development of Strategies for the Control and Eradication of Japanese Knotweed [MPhil Thesis, University of Exeter] <https://ore.exeter.ac.uk/repository/handle/10871/11862>

[2]     Cornwall County Council (2016) ‘Japanese Knotweed Legal Issues’ [website accessed 4/7/2016] <https://www.cornwall.gov.uk/environment-and-planning/trees-hedges-and-woodland/invasive-plants/japanese-knotweed/japanese-knotweed-legal-issues/>

Plants and war

Posted on by andy.winfield

By Helen Roberts

For centuries plants have been closely entangled in the complexities of wars and hostilities. Shortages of food during periods of conflict are one of the most pronounced impacts on humans. Conflict can impede our ability to grow and harvest crops as well as distribute food. Restricting the movement of food is a tactic that is used to control territories and ultimately bring down enemies. 
In the 1990s, in sub-Saharan Africa, many countries suffered famine as a result of conflict and this was primarily due to the different sides using food and hunger as political tools. As well as immediate famine in those areas of active war, there were indirect impacts as people were displaced by war and could not return home to plant their crops. Even more recent examples include the siege warfare occurring in many parts of Syria where the act of starvation is used to make opposing sides submit. The devastation and suffering as a result of food shortages to humans is untold during conflict, but the ultimate survival of certain plants can be threatened too.  

Saving seeds in Svalbard

Svalbard Global Seed Vault, Norway.
Photo credit: Amber Case [via Flickr CC licence]

Seed banks – facilities that specialise in collecting and storing seeds that society has deemed worthy of cultivation – are critical in preserving and potentially restoring the plants lost as a result of war. In 2015, researchers made the first ever withdrawal of 38,000 seed samples from such a bank in order to rebuild a seed collection to replace one lost to the conflict in Syria. 

In 2012, when war reached Aleppo, Syria, researchers from the International Center for Agriculture Research in the Dry Areas (ICARDA) shipped seeds representing 87% of their collection to the Svalbard Global Seed Vault in Norway (a subsequent blog will follow on this unique seed bank facility). The remaining seed was shipped out to other international seed banks. The ICARDA facility in Aleppo hosted seed from 150,000 specimens of significant agricultural importance from the Fertile Crescent – the birthplace of agriculture. Many of the plant varieties do not exist in the wild any more, including unique landraces and wild relatives of cereals, legumes and forages and are only represented in seed banks. 
Having fled Aleppo, ICARDA researchers, now in Terbol, Lebanon, have withdrawn some of this seed from Svalbard in order to recreate the collection lost in the war torn city of Aleppo. Seed was also sent to another ICARDA facility in Morocco. The seeds will be planted and allowed to germinate, grown up and seed collected and sent back to Svalbard to continue the loop of important seed conversation and diversity. At the facilities in Lebanon and Morocco, agricultural research will continue on the seed samples with germplasm being distributed worldwide to plant breeders. 

Russian scientists protect seeds with their lives

It is not the first time that scientists have battled for seed survival. Russian scientists during the Second World War were so desperate in their unerring determination to protect an internationally important seed bank from devastation that lives were lost. The man in charge of the collection was Nikolai Vavilov, a Soviet botanist and geneticist most famous for his work on the evolution of domesticated plants. As a child, he had witnessed first hand the horror of food shortages and this spurred him on to a follow a career in the plant sciences concentrating on plant breeding in order to help combat famine in Russia. He has long been considered the founder of modern seed banks. 
Unfortunately, Stalin who foolishly sought short-term solutions to Russia’s problem of famine, did not support his work. Vavilov fell from favour and whilst on a plant collecting expedition in the Carpathian Mountains was taken and incarcerated, slowly dying in prison of starvation in 1943. Vavilov’s vast seed bank survived the 872-day Siege of Leningrad. Dedicated scientists bent on protecting this valuable collection, barricaded themselves into the seed bank building and guarded it against looting. Sadly, they succumbed to either starvation or disease. This was an ironic tragedy considering they refused to eat any of the seed they were so intent on protecting. 

Plant-based resources in short supply

Not only does conflict cause basic food shortages and threaten plant species survival but it can affect the availability of important plant-based resources. Commodities such as rubber, coal, paper, timber, drugs, cotton and hemp, all derived from plants, have played a key part in conflicts. Of course, control of these critical resources has also propelled countries into war, including tea, spices, salt, grain, flour, bread, sugar and rice. 
One of the many ‘Dig for Victory’ posters
of the Second World War.

War also pushes the agricultural and manufacturing boundaries in the production of food and plant materials. One major commodity during the Second World War of vital importance was rubber. Natural rubber supplies from the plantations of Southeast Asia were severed at the start of the war and American forces were faced with the loss of a hugely important resource even though rubber had been stockpiled in the years preceding the war. With the fall of Singapore and the Dutch East Indies in 1942, rubber exports came to a complete standstill. The Americans invested heavily into developing synthetic rubber, but one of the twentieth century’s greatest ethnobotanists, Professor Richard Evans Schultes, was sent into the remote Amazon basin to hunt for wild rubber. For Schultes, this resulted in 12 years of exploratory research deep within the rainforest. 

People in Britain were growing their own to combat food shortages during the Second World War – spurred by iconic posters emblazoned with the words ‘Dig for Victory’. A staggering 1.4 million people dug up their gardens and lawns to grow vegetables and fruit in Britain. It was similarly successful in the US – by May 1943, 100 acres of land in the Portland area of Oregon was being cultivated by just children!

Plants used to commemorate lives lost

During and after conflict, many plants can hold particular meanings for people. The flowers of certain plants are commonly seen as peaceful elements imbuing a sense of calm and many plants are closely associated with the recognition and commemoration of those who have fallen in wars. The red poppy is one of the most emotive and unforgettable flowers because of war. A symbol of remembrance and hope, and worn by millions of people to remember those who have fallen in battle. The idea of using the poppies stemmed from one of the world’s truly poignant poems, ‘In Flanders Fields’ and is now inextricably entwined with the memory or war. It represents a powerful symbol of our relationship with a plant during and after conflict.

Helen Roberts is a trained landscape architect with a background in plant sciences. She is a probationary member of the Garden Media Guild and a regular contributor to the University of Bristol Botanic Garden blog.

Sources:

  1. Seed bank aims to protect world’s agricultural inheritance from Syria war. (2016). The Guardian. <http://www.theguardian.com/world/2016/feb/24/seed-bank-aims-to-protect-worlds-agricultural-inheritance-from-syria-war>
  2. ICARDA’s update on its seed retrival from Svalbard <http://www.icarda.org/update/icarda’s-seed-retrieval-mission-svalbard-seed-vault#sthash.5nrDjLb8.dpbs>
  3. Richard D. Bardgett. (2016). Earth Matters: How Soil Underlies Civilization.  Oxford: Oxford University Press.
  4. Wade Davis. (1996). One River: Science, Adventure and Hallucinogenics in the Amazon Basin. London: Simon & Schuster Ltd. 
  5. Kathy Willis & Carolyn Fry. (2014). Plants: From Roots to Riches. London: John Murray. 

The resilient plants of the western Mediterranean

Posted on by andy.winfield

By Helen Roberts

A recent talk to the Friends by Dr Chris Thorogood on the flora of the western Mediterranean was tonic for those of us longing for warmer weather. For Chris, the western Mediterranean has always had great appeal having spent many summers teaching field courses to undergraduate students at the University of Bristol and the last five years conducting fieldwork for his new book, a field guide to the area.

“The flora of the Western Mediterranean is really special. The plants are able to grow in some fascinating but really harsh places,” explains Chris. “Because of these severe conditions, plants have evolved numerous coping mechanisms in order to survive.”

The region is extremely rich botanically, with over 10,000 different species, all of which are specially adapted to particularly taxing conditions. The area covers a huge geographical expanse incorporating the westerly Portuguese Algarve, to Italy in the east, the islands (Balearic Islands, Corsica and Sardinia) and North Africa from Morocco to Tunisia (see my post last week, which discusses these regions in more detail).

A bounty of habitats: scrubby landscapes

There is a diverse range of floral habitats in the region from the scrubby maquis to forests with wonderful understories of orchids. The bare and arid habitats are home to ‘experts’ in drought tolerance; and at the other end of the watery spectrum are the seasonal lakes where deadly predatory plants reside. Humans have shaped the flora as well through thousands of years of agriculture, which has produced a visually evocative landscape throughout the whole Mediterranean basin.

Cistus ladanifer, the common gum cistus.
Photo credit: Henry Bush [via Flickr, CC]

A habitat that we so often associate with the Mediterranean landscape is maquis, which is specific to the Mediterranean area. It is comprised of spiny sclerophyllous  (a fancy word for hard-leafed) tough vegetation, which is specially adapted to cope with severe drought. There are often small trees and shrubs dotted about, often with beautiful understories of bulbs and short-lived annuals. Many of the species are aromatic. Typical species include prickly juniper (Juniperus oxycedrus) and common gum cistus (Cistus ladanifer), both highly pungent plants that are used by the cosmetic industry for their oils.

“The smells that exude from maquis vegetation are wonderful,” exclaims Chris, “and the scent from these aromatic plants just seems to hang on your clothes long afterwards.”

Garrigue vegetation is similar to that of maquis. It differs slightly in that it is low growing in form, occurs closer to the coasts and grows on shallower soils. Due to its close proximity to the coast it is battered by winter storms and winds. The low stature of the garrigue evergreen scrub means that perennials and bulbs are highly visible. The flowering displays in spring are visually spectacular and include wild tulips, crocuses, thymes, mints, helichrysums and lavenders.

Into the woods

The native forests of the western Mediterranean form prominent landscapes occupying quite different terrain than the shrubland regions. The oak woodlands are dominated by the holm and cork oak, with a spectacular understory that offers a refuge for many animals, including the endangered Iberian lynx.

The pine forests of Pinus halepensis and Pinus pinaster occupy coasts and cliffs. Healthy habitats have a particularly distinctive flora and fauna with rarities such as the semi-parasitic Violet Limadore orchid found in the maritime pine forest of Landes in France.

Ceratonia siliqua, commonly known as the carob tree.
Photo credit: Jesus Cabrera [via Flickr, CC]  

Humans have also shaped the forest landscapes of the region to a certain degree. Traditional farming practices in the Mediterranean have created unique assemblages of plants. Olive, carob, fig and almond groves represent landscapes people often associate with the Mediterranean. No other landscape denotes the true essence of the Mediterranean like a grove of olives. The olive is engrained in the lives and culture of the people of the region. Carob groves are also stunning in their composition with the gnarly dark trunks contrasting brilliantly against the green understory. The carob, Ceratonia siliqua, is a member of the ‘peas’ (Fabaceae), the most speciose family in the Mediterranean.

Rare aquatic habitats

Most of the western Mediterranean habitats are dry and parched, but surprisingly there are some wet ecosystems too. These unusual habitats are rare and include some curious species like the carnivorous bladderworts, found in seasonal lakes, which catch insect prey using sticky hairs and trap doors.

“The aquatic habitats of the western Mediterranean are interesting because they are pretty rare,” explained Chris. “Many are only seasonal but they support a wealth of interesting species from tiny forget-me-nots, tongue orchids and the carnivorous bladderworts.”

Tough but not invincible

While the native species of the western Mediterranean might be seen as tough and indestructible in the harsh landscapes they occupy, they are extremely susceptible to invasive alien species (IAS). Chris explained that the two most invasive plants in the region include certain species of Eucalyptus and Acacia. People assume these species are native, probably because they fit into the landscape visually and they can tolerate harsh climatic conditions. However, both these trees can alter native ecosystems and have a negative impact on biodiversity. Unfortunately, many are still planted as ornamental shrubs despite measures drawn up to prohibit the cultivation of them.

Chris explains the danger of one such exotic: “Acacia cyclops is an invasive species that is likely to become the next big invasive in the western Mediterranean. This species forms a mass of vegetation in barren landscapes due to its ability to cope with extremely dry and saline conditions. Ultimately it outcompetes native species.”

These invasive pests steal native plants’ water and change the biochemistry and microbiology of the soil. The native flora is sensitive because the western Mediterranean is exceptionally biodiverse in a relatively small area, with high levels of endemism, particularly on some of the islands. As well as the threat from IAS, there is also intense pressures on these fragile native habitats from humans due to urbanisation, afforestation, and coastal and agricultural development. Effective and timely conservation measures are vital to ensure the survival of these beautiful and botanically rich habitats before it is too late and they go into decline.

Helen Roberts is a trained landscape architect with a background in plant sciences. She is a probationary member of the Garden Media Guild and a regular contributor to the University of Bristol Botanic Garden blog.

The evolution of a predatory plant

Posted on by andy.winfield

By Nicola Temple

We keep a Venus flytrap (Dionaea muscipula) in our bathroom. My son begged me for it, which inevitably means I look after it. Having seen these carnivorous little delights in the glasshouses at the University of Bristol Botanic Garden, I have learned that humidity and moisture are key to its happiness – hence it’s bathroom location and its constant immersion in a tray of water.

The leaves of  the Venus flytrap, open (foreground) and
wrapped around its prey (background, right).
Photo credit: Shelby Temple
While I mostly leave my son to do the part he loves best – feeding – I can’t deny my own fascination with it. The leaves, converted to ambush traps through evolution, have to have enough stimulation by an unsuspecting insect to warrant the plant investing the energy to snap the trap shut.  Once the trap is shut, the plant estimates the size of the prey based on the amount of stimulation of the sensory ‘hairs’ triggered by the trapped (and no doubt panicked) insect. If there is a sufficient signal from the sensory hairs, the plant starts to produce enzymes and proteins that will help it digest and absorb the prey. It’s the stuff of nightmares…for the insect.
So what evolutionary steps transformed a leaf designed to harvest light from the sun into a leaf designed to trap prey? New research published this week in the journal Genome Researchhas provided some insight into the origins of the Venus flytrap’s trap.

It’s a leaf with a hint of root and a dash of…tongue?

Professors Rainer Hendrich and Jörg Schultz led a team of scientists from Julius-Maximilians-Universität Wüuzburg (JMU) in Bavaria, Germany who looked at the genes being expressed by the traps. They found that the traps not only had active genes typical of leaves, but also those typically found in roots.
A close up view of the trap, which shows the sensory ‘hairs’.
Photo credit: Shelby Temple
There are dome-shaped glands on the surface of the trap. The outer layer of each gland secretes the digestive enzymes, but the middle layer has foldings that increase the surface area – reminiscent of microvilli in the human intestine. It is thought that this is where nutrient absorption takes place. As this is a major function of roots, it is not surprising that some of the same genes are required.
Now…about about that tongue. I mentioned above that the plant releases digestive enzymes if it receives enough stimulation within the closed trap. But what if the insect dies very quickly after being trapped? The plant has a receptor in the trap that can detect chitin – the main constituent of an insect’s exoskeleton.  So even if the insect is no longer moving, the plant can ‘taste’ the insect in the trap and begin digesting.


Switching from defence to offence

When non-carnivorous plants come into contact with chitin, it is usually not going to turn out well for the plant –  they are under attack by herbivorous insects. Henrich and Schultz looked at the defence mechanism triggered by insects feeding on the non-carnivorous plant thale cress (Arabidopsis thaliana). They found that the plant in defence mode activates the same genes in the same pattern as the Venus flytrap in attack mode.
“In the Venus flytrap these defensive processes have been reprogrammed during evolution. The plant now uses them to eat insects,” explains Hedrich.
In both cases, mechanical stimulation (whether a chewing insect or a trapped one) generates an electrical impulse that activates the release of the hormone jasmonate. In Arabidopsisthis hormone begins a cascade of events that starts the production of various chemicals that deter the insect or make the leaves hard to digest. In the Venus flytrap, however, jasmonate starts the digestion of the insect and uptake of the nutrients.
So, the ancestor of the Venus flytrap had all the machinery in place for detecting insects and triggering a chemical response to their presence, but evolution managed to shift it from a defensive strategy to a very effective offence.

Source: 

“Venus flytrap carnivorous life style builds on herbivore defense strategies”, Felix Bemm, Dirk Becker, Christina Larisch, Ines Kreuzer, Maria Escalante-Perez, Waltraud X. Schulze, Markus Ankenbrand, Anna-Lena Keller Van der Weyer, Elzbieta Krol, Khaled A. Al-Rasheid, Axel Mithöfer, Andreas P. Weber, Jörg Schultz, Rainer Hedrich. Genome Research, DOI: 10.1101/gr.202200.115

Plants that work together

Posted on by andy.winfield

By Helen Roberts

As we roll into spring, gardeners eagerly collect packets of flower and vegetable seed to plant in their gardens. I have my disorganised pile of seeds ready and waiting, nestled in their respective packets, overflowing out of a tin stored on my kitchen dresser. Random seed that I have gleaned from gardens over the course of the year can be found in bags and random pockets.

Companion planting.
Photo credit: Brian Pettinger courtesy of Flickr.

My vegetable garden at home is minuscule and consists of a number of pots in the front and rear garden. I don’t own a greenhouse but use an area in my parent’s and beg ground from a friend to grow larger vegetables. Space is limited and therefore my crop is valuable. I don’t want attacks by cabbage white or carrot fly, I need to grow at different levels to maximise space and grow a wide range of small crops to give a varied meal. This has made me think more about what I can do to increase my crop productivity. I never use pesticides or herbicides in my garden and my resolve in this has been reinforced by recent press coverage over the importance of urban gardens for pollinators. I actually quite like cabbage white butterflies – my children do anyway – and they would be horrified if they knew I sprayed to rid the garden of them. Instead, I have decided to use the art of companion planting.

What is companion planting?

Companion planting is an age-old agricultural technique used for centuries across the world. It involves the idea of planting crops that are mutually beneficial to each other in order to increase productivity.

Why should gardeners companion plant?

Companion planting has a very wide number of benefits and uses:

1. Mix it up

It is best not to put all of your eggs in one basket when growing crops – grow a mix of crops rather than a monoculture so if one crop fails you have other crops as a fall back option. Moreover, a mix of crops will make it more difficult for pests to find their host plants, a hypothesis known as the ‘disruptive-crop hypothesis’.

2. Plants that give a helping hand

The other advantage is, if like me your garden is space constrained, you can plant on different levels. For example, a tall crop (such as corn) can provide a trellis support for a climbing crop (such as beans) and a ground crop (such as squash) provides shade and discourages weeds. You get three crops in a small amount of space and the companion plants provide physical advantages for the other crops.

3. Provide a home

Some plants provide shelter and shade for other plants; for example, the planting of corn can provide shade for lettuce or spinach (although most vegetable planting in this country requires as much sun as possible). Companion plants can also provide refuges for many beneficial insects.

4. Pest control

Marigolds are supposed to help keep aphids away from tomato
plants. Photo credit: Ruth Hartnup (on Flickr).

Companion planting is also supposedly helpful in pest suppression through the release of repellent chemicals. Numerous companion plants also attract beneficial insects, such as ladybirds and lacewings, which predate on crop pests and many of these insects also act as important pollinators. Some plant species are used as ‘trap-crops’ drawing the attention of pests away from the crop and acting as sacrificial plants. Companion plants also provide a visual distraction to pests. In a monoculture, pests move easily from one plant to another, but companion plants break up this assault.

Folklore or scientific fact?

It is hard to know whether some traditional planting combinations that have endured the decades are based on any sound evidence of benefits. Certainly there is plenty of information about companion planting in the popular press and gardening books, but most is not backed up by any rigorous scientific trials in the peer reviewed literature. In academic literature, experimental results investigating the use of certain companion plants are varied as to their effectiveness. Here are some examples that I have come across:

Odorous onions

I learned from my maternal grandfather to plant Allium species in amongst my carrot rows to help deter the pesky carrot fly, Psila rosae. This annoying pest feeds not only on the roots of carrots but also on other crops too including parsnip, celery, parsley and celeriac. The small 9 mm creamy white maggots cause scarring of the tap roots making them inedible and more prone to secondary rots. This year I plan to plant my carrots in amongst garlic chives, a plant similar to the onion chive and which also produces pretty white edible flowers.

It is generally thought that aromatic species deter pests by exuding repellent chemicals. Most relevant to the carrot-allium combination was a study that looked at mixed cropping of onion and carrots and the effects on pests of these crops. They found that there were reduced attacks by carrot fly compared to monocultures of both crops and that when the plants were planted together in high densities this also reduced plant pests and increased predators of carrot fly eggs. Stan Finch and his colleagues from Horticulture Research International in Warwick found no evidence that odours from aromatic plants repel or deter crop pests, suggesting that reduced attacks on host plants were a result of other mechanisms, such as simple disruptive effect.

Get a sniff of marigolds

I am not a big fan of Tagetes species, more commonly known as marigolds. They just remind me of old fashioned bedding plants in staid Victorian parks, but if they ward off pests in the vegetable plot then I am willing to use them. Tagetes sp. exude a strong odour that is apparently not pleasant for plant pests. They are supposedly useful to plant with tomatoes to ward off greenfly but I have yet to find any scientific literature to support this planting combination. Again, Finch and his associates specifically found that it was not the odour of the marigolds that repelled the pests, but simply the fact that they acted as a diversion for the pests.

Setting a trap

I often grow pots of nasturtium (Tropaeolum majus) in my garden. I like the look of the flowers and especially the leaves, using them as salad garnishes and the seed to make capers. This plant is said to help attract black fly, aphids and other pests away from host plants acting as a crop trap and functioning as a sacrificial plant. There are mixed results as to whether nasturtiums really do this. One year in my garden I grew cabbage and nasturtium together and both crops were smothered in cabbage white caterpillars. The butterflies definitely did not show a preference for the Nasturtium and the caterpillars eventually obliterated both plants. Certainly there is not a wide range of recent academic literature investigating the use of nasturtiums as a companion plant. However, according to the Royal Horticultural Society (RHS), this plant is beneficial to pollinators and as I can also eat it, I plan to trial a variety known as Blue Pepe, known for its distinctive bluish leaves and bright red flowers.

The scientific literature on many companion plant combinations is mixed, but what is clear is that there are no disadvantages to using companion planting. The physical advantages of companion planting will be evident even if the other benefits are less obvious, and many companion plants can be found in the RHS’s ‘Perfect for Pollinators plant list‘. Even if you don’t get increased crop productivity, then the garden will be diverse and look beautiful too.

Helen Roberts is a trained landscape architect with a background in plant sciences. She is a probationary member of the Garden Media Guild and a regular contributor to the University of Bristol Botanic Garden blog.

Sources:

Associate Professor Jane Mt. Pleasant 

Uvah, I. I. I. and Coaker, T. H.  Effect of mixed cropping on some insect pests of carrots and onions. Entomologia Experimentalis et Applicata 1984; 36: 159-167

Finch, S., Billiald, H. and Collier, R. H. Companion planting-do aromatic plants disrupt host-plant finding by the cabbage root fly and the onion fly more effectively than non-aromatic plants? Entomologia Experimentalis et Applicata 2003; 109: 183-195

Plants more resilient than animals through mass extinctions

Posted on by andy.winfield

By Nicola Temple

The fossil record suggests that a diversity of land plants had evolved by about 472 million years ago (mya). There is evidence to suggest that plants made the move onto land as much as 700 mya [1], placing them in the midst of the five largest extinction events to have shaped life on our planet.

Researchers from the University of Gothenburg released a study earlier this year showing that plants have generally been more resilient to these extinction events than animals. They looked at more than 20,000 plant fossils to see how these mass extinction events affected plant diversity [2].

Ferns and horsetails dominated the
landscape by the end of the Devonian.
Credit: Nicola Temple

They found, not unexpectedly, that each group of plants fared differently through each extinction event – with some doing better than others. Though plants might experience mass extinctions, the researchers concluded that plants also began to diversify again quickly after such events, so that more new species were being generated than were being lost.

“In the plant kingdom, mass extinction events can be seen as opportunities for turnover leading to renewed biodiversity,” said leading author Daniele Silvestro.

The big five

Scientists have identified five mass extinction events since land plants have evolved.

Ordovician – Silurian mass extinction (approximately 443 mya): This event wiped out approximately 85% of sea-dwelling creatures, such as trilobites. It has been hypothesised that a huge ice sheet in the southern hemisphere led to the alteration of climate patterns, a drop in the sea-level and a change in ocean chemistry.

Late Devonian (approximately 359 mya): This event is likely a series of smaller extinction events that happened over several million years, but the end result was a loss of 75% of all species on Earth. Changes in sea level, multiple asteroid impacts and new plants that were changing the soil chemistry have all been attributed to this period of extinction.

Permian (approximately 248 mya): It is estimated that 96% of all species were wiped out during this mass extinction. Marine creatures were badly affected and it is the only extinction thought to have had an impact on insects. Hypotheses as to what led to the demise of so many creatures have included combinations of asteroid impacts, volcanic activity, methane releases and decreased oxygen levels.

Triassic – Jurassic (approximately 200 mya): A mere fifty million years after the Permian extinction, about fifty percent of life was wiped out again. Plants seem to have been largely unaffected by this extinction event, but many of the marine reptiles were lost as well as large amphibians and cephalopod molluscs. Large scale volcanic activity and asteroid impacts have both been credited for these extinctions.

This dinosaur can still be spotted in the Evolutionary Dell
at the Botanic Garden! Credit: Nicola Temple

Cretaceous – Paleogene (approximately 65 mya): This extinction event is well known for the loss of the dinosaurs, pterosaurs and ammonites. The prevailing theory for this extinction is the impact of a large asteroid off the coast of Yucatán, Mexico and the subsequent fall-out effects.

While each of these mass extinction events meant the widespread loss of species, they also opened up opportunities for diversification and new species. Had the dinosaurs not gone extinct, for example, mammals would likely not have diversified, compromising our own lineage as humans. Flowering plants experienced extensive diversification after the Cretaceous – Paleogene event and they remain a dominant group today.

The key to resistence might be in duplicate DNA

The Wollemi Pine (Wollemia nobilis)
on display at the Botanic Garden has fossils
dating back 200 million years.
Credit: Nicola Temple

The majority of plants have undergone one or more duplication events where an exact copy of their entire genome is created. This is known as polyploidy – multiple copies of the same genome. Bread wheat, as an example, is hexaploid as it has six sets of chromosomes. Research has shown that one of these doubling events coincides with the Cretaceous – Paleogene mass extinction, approximately 65 million years ago[3].

An extra set of chromosomes could be quite convenient during a prolonged period of stress, such as a massive asteroid strike and its subsequent effects.  Polyploids might be better equipped to resist harmful mutations or perhaps take on mutations that offer a selective advantage under new conditions. Polyploidy plants also tend to be self-fertilising or asexual reproducers, which would be another advantage at a time when finding a partner for breeding could be limited.

Looking forward to a time of inevitable change

The theory that polyploidy confers an advantage during times of change can be witnessed in today’s extreme environments. There is evidence from the Arctic that polyploid plants are more successful than diploid plants at colonising habitats left by receding glaciers [3].

The Evolution of Land Plants Display at the Botanic Garden
(wrapped up for winter) is a walk through time.
Credit: Nicola Temple

Looking into extreme and changing habitats, such as the Arctic, as well as back into the fossil record can give us some indications of which plant groups may be more resilient to the changing climate we are currently experiencing.

You can take a walk through time in the University of Bristol Botanic Garden’s Evolution of Land Plants Display. There you will see living representatives from the groups of land plants that lived from the Cambrian to the Cretaceous, including unusual plants like Wollemi Pine (Wollemia nobilis) with fossils dating back 200 million years.

References:

[1] ‘First land plants and fungi changed Earth’s climate, paving the way for explosive evolution of land animals, new gene study suggests’, Penn State Science < http://science.psu.edu/news-and-events/2001-news/Hedges8-2001.htm>
[2] Silvestro D, Cascales-Miñana B, Bacon CD, Antonelli A (2015). Revisiting the origin and diversification of vascular plants through a comprehensive Bayesian analysis of the fossil record. New Phytologist (in press).
[3] Yong E (23 Mar 2009) ‘Extra genomes helped plants to survive extinction event that killed dinosaurs’, Not Exactly Rocket Science [blog] <http://scienceblogs.com/notrocketscience/2009/03/23/extra-genomes-helped-plants-to-survive-extinction-event-that/>

Some like it hot

Posted on by andy.winfield

By Helen Roberts

With the dismal wet wintry weather prevailing in the UK at this time of year, most people look forward to the return of warm long days, evenings outside and picnics on the beach. Things can look a little dreary and dull in people’s gardens at the moment, before the arrival of spring and its profusion of bulbs and other spring flowers. The Mediterranean collection at the University of Bristol Botanic Gardens helps to remind me of summer sun and balmy places.

Maquis: scrubland vegetation of the Mediterranean

Maquis shrubland in Conca de Dalt of Catalonia, northeastern Spain.
Photo by Gustau Erill i Pinyot.
Licensed under CC BY-SA 3.0 via Wikimedia Commons 
The Mediterranean Basin of Europe and North Africa display shows examples from different vegetation biomes; the collection includes evergreen forest, maquis or macchie and garique. Many of the highly aromatic and fragrant plants are associated with maquis vegetation. The maquis biome, which often includes leathery broadleaves, evergreen shrubs and small trees, usually occurs on the lower slopes of mountains bordering the Mediterranean Sea.
The climate of the maquis biome is characterised by long dry summers and short mild wet winters, with low annual rainfall. Ocean currents and fog influence the temperature and limit the growing season. The plants that grow here cope with the very hot summers by entering a slow growth period or dormant phase so they can resist long periods of drought.
Plant defences in this harsh environment are numerous. Many shrubs and low growing vegetation have thick tough leathery leaves, which reduce water loss but also deter hungry herbivores from grazing. Many plants contain volatile organic compounds (VOCs). These chemicals help facilitate interactions between plants and the environment – from attracting pollinators and seed dispensers to warding off pathogens, parasites and herbivores. When a plant is under attack from a herbivore, for example, it will release a chemical cocktail of VOCs, some of which have been found to attract natural predators of the herbivores. VOCs are also good at leaching into surrounding soil and so will deter the growth of other plants.
Plants containing VOCs are often very flammable, which is partly why areas of maquis are prone to wild fires.

Pyrophytes need a little fire in their lifecycle

Montpelier cistus (Cistus monspeliensis).
Photo by Jean-Pol GRANDMONT
via Wikimedia Commons
Many of the plants in the maquis biomes are pyrophytes (fire loving plants) and require wild fires for reproduction, recycling of nutrients and removal of dead vegetation. Pyrophytes can be classed as active or passive. Active pyrophytes actually encourage fires as they often require fire in order to reproduce. Passive pyrophytes resist the effects of fires.
An active pyrophyte growing in the University of Bristol Botanic Garden maquis biome is Cistus monspeliensis, commonly known as the Montpelier cistus or rock rose. When a fire starts, Cistushas evolved to burn. This combustible conclusion to the adult plant helps destroy competing plants near to it. However, unlike its competitors, the fire will mechanically rupture the seeds of Cistus and the smoke and heat will trigger germination of the next generation. The Cistus seedlings have the advantage of beginning life in a competitor-free environment.
A closed cone and foliage of Pinus pinea.
 Licensed under CC BY-SA 2.5 es via Wikimedia Commons 
Pinus pinea (the stone pine) is also in the Botanic Garden’s collection and it is a passive pyrophyte. It has a thick bark with high moisture content to help it resist fire. Its hard-coated fire resistant cones open when exposed to high temperatures. This is particularly useful in the harvest of the desirable seeds, known to many of us as pine nuts. As the tree grows, it self-prunes the lower branches, which helps prevent the fire travelling at ground level from jumping up into the canopy and potentially destroying the tree.
Some species spring back from fire events by sprouting new growth from the old. There are two such sprouter species in the Botanic Garden’s collection. The carob tree (Ceratonia siliqua) re-sprouts from epicormicbuds that lie dormant beneath the bark. These buds are normally suppressed by hormones produced by active shoots, but after a fire event and the destruction of the foliage, the buds are activated. Erica arborea (tree heath) re-sprouts from root crowns so is known as a below ground sprouter. It produces seed in the first post-fire summer.
Fire adapted plants of the maquis biome are only a handful of those plants making up the Garden’s Mediterranean collection. The collection also includes plants (some of which are also pyrophytes) from the southwestern tip of South Africa and displays are also under development from the Western andSouthern Australian, Chilean and Californian Mediterranean climate regions.
The half hardy plants of the Mediterranean collection are planted out in each respective biome in the summer, whilst more tender plants are protected from our cooler Bristol temperatures in the warm temperate and cool zones of the glasshouses. The outdoor collection sits on a south facing rocky bank to maximise the amount of sun and aid drainage. The path meanders through the collection allowing visitors to appreciate the appearance and fragrances of the different plants. These are all good things to look forward to in the summer months, but meanwhile if you have the chance to warm yourself in front of a crackling fire, think of those volatile fire-loving plants! 

A walk through the mendips

Posted on by andy.winfield

By Helen Roberts

A few weeks ago our family, had a great day out walking on the Mendip Hills. We set off in autumn sunshine, through pretty deciduous woodland, to an Iron Age hill fort called Dolebury Warren – an upland area of calcareous grassland. Having lived on the edge of the Mendips during my childhood, I am always keen to show my children where I used to explore as a youngster.
Part of Cheddar Gorge, Somerset, England, seen from a
light aircraft. Photo by Adrian Pingstone (1975).
The Mendips are a range of mainly carboniferous limestone hills comprised of at least four convex fold structures formed between 363 and 325 million years ago, during the end of the Carboniferous Period. Weathering of the limestone has resulted in features including gorges, dry valleys, screes and swallets (sink-holes) and incorporates the famous Cheddar Gorge and Burrington Combe, each with extensive cave systems. The area also has interesting landscape characteristics like limestone pavements and other karst structures.
The geology of the Mendips makes for interesting ecological communities and consists of large areas of open calcareous grassland with many rare flowering plants. For instance, Dolebury Warren owned by the National Trust and managed by Avon Wildlife Trust, sits within the Mendip Hills Area of Outstanding Natural Beauty and is a Site of Special Scientific Interest due to its important limestone flower communities. These flower communities attract up to 70% of all British butterfly species. Dolebury Warren has a gradation of communities from species rich calcareous grassland, through acid grassland to limestone heathland, with large areas of mixed scrub.
Cheddar Pink (Dianthus gratianopolitanus).
Photo by Paul Harvey, via Wikimedia Commons
The charity Plantlife has identified the Mendips as an Important Plant Area (IPA), which is an area of landscape that has very high botanical importance. Some plant species found on the Mendips are found nowhere else. Due to factors such as over grazing, poor land management, scrub encroachment and agricultural intensification, these plants are declining in numbers and some are threatened with extinction. The University of Bristol Botanic Gardenhas a local flora and rare native plant collection, which includes a sub-collection from the Mendip Hills, Limestone Cliffs and Coastal Islands. The collection was developed to help grow and interpret some of the rare and threatened plant species found in these habitats. The collection represents an important habitat and phytogeographic display and is helping meet the objectives of the ‘Global Strategy forPlant Conservation’.

Rare plants of the Mendips 


One of the Mendip plants in the Botanic Garden’s collection is the Cheddar Pink (Dianthus gratianopolitanus). This is a very pretty scented pink flower that grows in a few places on the Mendips but mostly at the original site of Cheddar Gorge. This plant was originally discovered about 300 years ago and is considered the pride of Somerset and was voted the County Flower. It grows best in rock crevices, high on the limestone crags of the Gorge, and can be seen in June and July using binoculars to search patches of colour visible on the cliffs, just above the road.
Also growing at the Gardens is the interestingly named Starved Sedge (Carex depauperata). This is an exceptionally endangered plant that is only found in one local area – in the woods and on a hedge bank near the small town of Axbridge. This is one of only two sites in the whole of the UK. Fifteen years ago, Starved Sedge had declined to such an extent that there was only one plant in the whole of Britain. As appearances go, it’s not much to look at. It’s a tussocky plant with trailing leaves and gigantic seeds and can easily be mistaken for some common woodland grasses. A reintroduction programme has improved the status of this plant by using cuttings and seed collecting to re-establish it at other sites in the UK.
The University Botanic Garden are also helping to preserve another plant at high risk of extinction and classed as nationally rare, known as Somerset Hair-grass (Koeleria vallesiana). Again, this is a fairly innocuous grass restricted to the Mendip Hills with very slow spreading habit. The Bristol Botanic Garden’s specimens were collected from Brean Down, which is the most westerly part of the Mendip Hills, as well as the interesting tiny islands of Steep Holm and Flat Holm.
Brean Down is an outstanding example of calcareous grassland and supports endemic plant communities that provide for many important insect communities. Other important plant species growing at Brean Down and now growing at Bristol Botanic Gardens include the White Rockrose (Helianthemum appenninum). This is an attractive white flowered perennial sub shrub, which frequently grows on southern slopes. White Rockrose, Somerset Hair-grass and Dwarf Sedge (Carex humilis) are all particularly at risk due to scrub colonization. This highlights the importance of grazing to maintain grassland habitats. The National Trust introduced grazing by long horned White Park Cattle and British WhiteCattle (feral goats are already on Brean Down) to help keep the grass short and scrub species controlled. 
The rarity of the plants found on the Mendip Hills highlights how important collections, such as those held at the University Botanic Garden, are for ensuring the survival of plants teetering on the brink of extinction. Equivalent to a botanical savings account, these collections help ensure that if plant species are lost, they can be reintroduced back into the wild.