4 Dec 2013
Last month the Professional Horticulture Group South West held its annual Christmas lunch (well you have to start sometime) at Wiltshire College's Lackham campus. The guest speaker was Nick Morgan, Senior Superintendent RHS Garden Wisley, who described the trials and tribulations of constructing and managing the new Wisley Glasshouse. A summary of part of his talk appears below.
After lunch a tree planting ceremony was held in memory of Oliver Menhinick, a former Head of Horticulture at the college and member of the Group who was killed in an accident during one of the Group's meeting earlier in the year. The planting was undertaken by Nicholas Wray, Curator of the University of Bristol Botanic Garden and James Chamberlain, Oliver's step-son (the picture shows James planting the tree while Nick provides support).
Development of the Wisley Glasshouse
Although the RHS was founded in 1804, the early RHS gardens were based in Chiswick and South Kensington. It was not until a century later in 1904 that they acquired the gardens at Wisley. The initial 'greenhouse' range built at that time was a series of the traditional vinery glasshouses widely used in commercial horticulture at that time.
These survived until 1969 but, being wooden structures, by this time they were showing their age. In 1969 a new aluminium glasshouse was opened higher up on the Wisley site. This structure was widespan glass, once again typical of the commercial houses of its time. Such glasshouses were usually reckoned to have a twenty year life so by the turn of the millennium they had outlived their usefulness.
Having decided that a new greenhouse was needed, the RHS needed both a site and a design, not to mention the money to deliver the end product. After examining several possibilities the site chosen was an underused level area in the north-west corner of the gardens flanked by the river Wey. The site was typical local Bagshot sand but suffered from a high water table so a comprehensive drainage system was installed around the site to cope with this.
The project required £7.5million and raising this was a challenge. In the end it was not one large donations but a mix of larger and smaller donations. Hundreds of RHS members can claim to have helped pay for it through their donations and many of these are commemorated on glass panels alongside the approach to the main entrance to the glasshouse.
In choosing the design they were particularly attracted to the possibilities of curved glass demonstrated by Dutch glasshouse manufacturer Smiemans Projecten and, in the fullness of time, they were selected to design and build the structure we see today.
However, before they could start the building the site had to be inspected to ensure there were no bat colonies living in the old oak trees that were scattered across the site and then a team of archaeologists arrived to survey the area to ensure there were no important remains of historical interest. Fortunately neither of these inspections identified anything to hold up progress on the build.
To assist with groundwater control the ground level raised by 0.5 metre. Then, in order to provide a firmer foundation, stone filled piles were drilled into the Bagshot sand and capped by concrete plates. The framework was built on these and then glazed. The glass sheets are up to 7m2 of 4mm toughened glass. Nevertheless they arrive as flat sheets and are flexible enough to be bent into the curves. Only one sheet broke during the whole process and that was while taking it off the lorry. Their faith in curves has been justified as the new glasshouse has proved to have much better winter light quality.
The final structure is 13m high and 3000m2 in area. It is heated by spiral hot water heating coils in the roof with paddle fans pushing the heat down. In addition finned tubes around the sides provide extra heating capacity.
Behind the 'public' glasshouse there is a service glasshouse of standard Venlo design where replacement plants can be propagated to keep the displays updated.
They wanted to divide the tropical and temperate sections of the glasshouse with rocks but these were going to be too heavy. Instead they opted for glass reinforced concrete replicas created by Rock themes International.
When Nick was asked to go and source plants he had visions of trips to far-off places but had to make do with a day at Fachjan Project Plants in Holland which supplied many of the larger specimens that provide the framework planting.
Once the glasshouse was finished and planted, the lake and the plantings around it could be completed in readiness for the final opening by the Queen in June 2007. Since then it has become the most visited part of the garden and has ousted the old laboratory block as the 'icon' of Wisley.
Medicinal Plant of the Month
Taxus baccata, English Yew, Taxaceae
The 25 July 2021 will mark the 400th anniversary of the founding of the Botanic Garden in Oxford. This also marks the beginning of botanical research and teaching at the University. In order to celebrate this anniversary, the Department of Plant Sciences, the University Herbaria and the Botanic Garden and Harcourt Arboretum are working together to 'countdown' the 400 weeks to the 400th anniversary by celebrating 400 culturally and scientifically important plants.
The countdown began on 24 November with Plant No 1, the English or European Yew.
A familiar, if somewhat gloomy sight in most churchyards, the European yew tree can live for thousands of years. Still a youngster, the largest yew tree growing in the Oxford Botanic Garden is also the oldest tree, planted in 1645 by the first Curator, Jacob Bobart (see catalogue, right). Although herbalists at the time said that this tree 'had no place among medicinal plants,' Bobart still planted an avenue of these trees in the UK's very first physic (medicinal) garden. More likely to be used in the 17th century for making longbows or knife handles, almost four centuries later, we know now that this tree does indeed have a place among medicinal plants.
In 1962 a sample of Taxus brevifolia, the Pacific yew was collected, from which a potent anti-cancer substance was subsequently isolated. This substance was found in such small amounts that six fully mature trees were required to provide enough drug substance to treat a single patient. The removal of the bark necessitated killing the trees - clearly not a sustainable supply.
However, the mode of action of paclitaxel was unravelled and found to be novel. Paclitaxel binds to a protein called tubulin which plays a key role in cell division (mitosis). The microtubules it binds to are prevented from disassembling, thereby stopping cell division. A new mode of action is appealing to the pharmaceutical industry as the drug should have a different (and one hopes, improved) profile to existing drugs. So the hunt began for an alternative supply.
The chemical structure of paclitaxel is complex and whilst several academic groups have achieved a chemical synthesis in the laboratory it is not feasible to produce commercial quantities in this manner. Different species in the same genus often contain similar molecules and so other species of yew from across the world were tested to see if they contained paclitaxel.
Eventually they found that a similar molecule can be isolated from the leaves of Taxus baccata, the English yew. With a small amount of modification in the laboratory this molecule could be converted to paclitaxel. Today paclitaxel (Taxol) has been joined on the market by docetaxel (Taxotere), a slightly more water-soluble analogue.
Paclitaxel is used to treat ovarian cancer and both drugs are used to treat breast cancer and non-small cell lung cancer. Commercial supplies of paclitaxel now come from a plant cell culture technique initially developed by scientists in the United States Department of Agriculture and then licensed to a commercial company.
Picture right: The familiar flowers and fruits of the Yew Tree (pictures courtesy of Oxford Botanic Garden).
The story of Taxol , Nature and politics in the pursuit of an anti-cancer drug by Jordan Goodman and Vivien Walsh. Cambridge University Press, ISBN: 0-521-56123-X
The full countdown can be followed on twitter @Plants400 or online at: www.herbaria.plants.ox.ac.uk/bol/plants400
Oxford Botanic Garden
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It's the microbes that count
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Events of Interest
Positive Plant Microbial Interactions: Their role in maintaining sustainable and natural ecosystems
2 - 3 Dec, Association of Applied Biologists
Plant Genomes & Biotechnology: From Genes to Networks
4 Dec, Cold Spring Harbor Laboratory
Cold Spring Harbor, USA
Quality Management in Postharvest Systems
4 - 7 Dec, International Society for Horticultural Science
Advances in Nematology
10 Dec, Association of Applied Biologists
Innovation and Trends in Bio-inspired Crop Protection
10 Dec, In Crops
Photo-Physiology Phenotyping Workshop
16 - 17 Dec, University of Essex
Rethinking Agricultural Systems in the UK
18 - 19 Dec, Association of Applied Biologists
International Advances in Pesticide Application
8 - 10 Jan, Association of Applied Biologists
8 - 10 Jan, Society of Experimental Biology
Brassica Growers' Conference and Trade Exhibition
21 Jan, Brassica Growers Association
Impact of Pesticides on Bee Health
22 - 24 Jan, SEB, SB, BES.
5 - 7 Feb, Messe Berlin
International Orchid Symposium
19 - 23 Feb, International Society for Horticultural Science
Plant Genomics Congress
24 - 25 Feb, Global Engage
Kuala Lumpur, Malaysia
Environmental Management & Crop Protection
25 - 26 Feb, Association for Crop Protection in Northern Britain
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