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Students set to tell the story behind the ballast seed collection

Guest post by Rhiannon Williams & Alex Learmont

The seeds of some plants can survive for many years lying dormant, waiting for improved environmental conditions to germinate. Seeds can withstand extreme drought or cold; some dry seeds can be stored at -150 degrees Celsius without harm, and still be induced to germinate!  Some seeds can be transported around the globe in the hulls of ships, immune to the storms and scurvy, only to one day be dumped on the banks of a foreign river, which may or may not provide the conditions it needs to grow and flourish.

We are biology students at the University of Bristol and for our dissertation we are creating interpretation boards for one of the Botanic Garden’s newer collections – the ballast seed collection. Our boards will be displayed at the Botanic Garden next to the ballast seed flower bed, which can be found near the glasshouses. This summer, once the flower bed has been planted up, it will be a joy to come and visit.

Alex Learmont and Rhiannon Williams are
preparing interpretation boards and
other materials on the ballast seed project
as part of their dissertation.
Our aim is to provide visitors of the gardens and the public with accessible and interesting information about the ballast seed project and the plants found within the collection. In addition to the interpretation boards, we are making A4 cards with information for each plant species and leaflets that will be available at the Garden and on tours of the floating garden at the harbourside. Visitors will even be able to scan QR codes placed beside some of the plants with their smartphones and access informative websites for some of the species. This collection is unique to the Botanic Garden and we’re looking forward to telling the remarkable story behind it.

The project began as part of the ‘Port City’ exhibition at the Arnolfini

The ‘Seeds of Change’ project is an on-going exploration of the ballast flora of European port cities by the artist Maria Thereza-Alves. Empty or lightly loaded ships carry low-value materials such as earth, stones and gravel, or sea water as ballast to weigh them down, giving improved manoeuvrability and stability. This ballast was emptied into the river Avon and onto ballast dumps that used to be present around Bristol. For centuries, exotic plant species have been transported to Bristol in the ballast of trading ships coming from countries all over the world.

The project began in 2007 as a part of the international Arnolfini exhibition entitled ‘Port City’ and was part of the London 2012 Festival. With the help of Botanic Garden curator Nick Wray, a list was composed of exotic plants found growing on ballast dumps throughout the UK, including the local port of Avonmouth. The full collection of these seeds was germinated in the University of Bristol Botanic Garden. Then with the support of the Arnolfini, the Botanic Garden and Bristol City Council, designer Gitta Gschwendtner used a condensed version of this collection to transform a disused grain barge on Bristol’s floating harbour into a ballast seed garden.

The floating garden can be viewed from Castle Park, but visitors can only reach it by boat. The next set of boat tours begin this spring. For a small fare, visitors can book onto them through the Arnolfini. Some of the tours focus particularly on the design and artistic concepts of the project whereas others are aimed more at those with a botanical interest. For example, last summer a micro-sound tour allowed visitors to listen to the sounds of plants growing.

Exotic plants reflect Bristol’s rich maritime history

The idea behind the project was to draw links between Bristol’s floral history and the social and economic history of Bristol’s trading past. Human dispersal of plants often follows routes of transportation, and the ballast of ships was a route into Bristol for invasive plant species. Some of the plants are native to the Mediterranean, West Asia, North Africa, and even South America. Ships would have been trading back and forth to these places over the past few hundred years. The plants in the collection convey a living history of Bristol’s rich maritime past.

Relatively few seeds in the ships ballast would have survived the long sea journeys, but some were able to germinate or lie dormant in the ballast dumps around Bristol for many years. In the late 1800s ballast became a more important aid to invasion when the new generation of metal ships changed from solid to liquid ballast. Ballast water can contain hundreds of species including bacterial, microbes, small invertebrates and seeds. Now, ballast is a major source of invasive species to port’s and in coastal freshwater and marine ecosystems. The International MaritimeOrganization (IMO) has developed a Convention aimed at preventing these harmful effects, this involves “Ballast water exchange”. The water taken up at the port of departure is replaced during the voyage with water from the deep sea. The organisms in the deep sea water are far less likely to survive when the water is discharged at the port of arrival, hence reducing the impact of invasive species in ballast water.

Most exotic seeds never establish themselves

In 1996, Williamson and Fitter proposed a ‘tens rule’. The rule states that only 10% of non-native species imported into a region will appear in the wild. Of these, only 10% will become established, and 10% of the establishing species may become invasive. Therefore, only 1 in a thousand imported species will cause problems.

An important message the ballast seed garden conveys is that most non-native flora does not become established or invasive. Even if the plants survived the long journey, the environment where they were unloaded from the ships (such as a ballast dump) was likely to be unsuitable for growth, or the number of plants of the same species was too small to result in a viable breeding population. However, some of the species on the ballast seed display are capable of survival and reproduction in the wild. Many of these naturalized species exist alongside British flora causing no obvious damage to habitats and ecosystems.  The Garden promotes the idea for multihorticulturalism: the view that migrations of species are natural and trying to stop them is futile.

New projects bring ‘Seeds of Change’ to schools and communities

During spring and summer 2013 a new project, “Seeds of Change: Growing a Living History of Bristol”, will provide the opportunity for Bristol schools and community groups to grow ballast seed gardens of their own. The project was set up by The University of Bristol Centre for Public Engagement and the Botanic Garden in partnership with the Arnolfini, and with funding provided by the Heritage Lottery Fund. Academics, artists and student volunteers from the university will be working together to lead a programme of activities and workshops exploring themes of history, botany and art; making the original themes of the “Seeds of Change” project exciting and accessible to school children and community groups.

For more information on the Heritage Lottery Funded schools and community programme you can visit the University website: or contact Martha Crean by email: or phone: 0117 3318313.


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