Tuesday, 29 July 2014

A Sweet Smelling Champion in our Midst

A champion amongst us
A plant which is worth giving a second glance to at the moment is Clerodendrum trichotomum var. fargesii, which is in the Lamiaceae, or mint family. It comes from China and Japan and arrived at the garden in 1989. Since then it has grown massively - it is classified as one of the Champion Trees on the Tree Register, because it is the largest known example in Britain. It is planted in the Fern Border in the North East corner of the Walled Garden.

It is a beautiful tree, with a branching, three tiered structural habit. It is flowering at the moment, filling the garden with a delicious aroma of jasmine-crossed-with-lemon blossoms. The flowers themselves are tiny and borne in clusters around the richly green, ovate leaves. Each flower consists of a long tube which divides out into five, almost star-like petals arising from a pink blushed, pale green calyx made up of five sepals. 
A honey bee visits a flower leaving behind a parcel of pollen
The flowers are pollinated by insects who take advantage of a nectar reward in exchange for carrying pollen from one flower to another. Freshly opened flowers are creamy white with four stamens, each carrying an upward reaching brown anther, and a single style pointing down towards the ground. As the flowers mature, the petals darken to a yellowish cream and the stamens turn backwards, and point down, while the style lifts up, ready to accept pollen from an insect. This is a clever way for the plant to avoid self-fertilisation, which results in poor genetic variation, and weaker offspring. In the autumn the flowers are replaced by turquoise fruit surrounded by sepals which turn a vivid pink, making this plant a point of interest later on in the year too.

In autumn 2013 a team from Oxford Botanic Garden and Harcourt Arboretum travelled to Japan on a seed collection trip. One of the plants collected was Clerodendrum trichotomum. To find out more about the Japan project take a look at our previous posts.

Autumn fruits of Clerodendrum trichotomum in the wild 

Tuesday, 22 July 2014

Botanic Garden reaches out

Over four weeks, the Outreach Education Officer Nicola Bird (who works over all the Oxford University Museums and Collections) has taken the Botanic Garden out to Abingdon Mind where a group of 12 people discovered food through a multisensory experience: its history, its classifications, its medicinal and cultural uses, and its journeys around the world.


The four weeks were split into sessions: Food as Medicine, Feeding the World, The 5 Senses and Spices. The group explored herbs and spices using their sense of smell and then guessed what our Victorian ancestors would have used them for (usually a purging of some sorts!). We also tasted foods which aren’t so common in the UK with people taking lots home to try, following the excellent recommendations on cooking methods from members of the group. 

We explored how the world uses food items in other ways - drinking gourds, musical instruments, materials – helping us look at the originality and resourcefulness of people around the world. Finally, accompanied by the calmness of fresh mint tea, we discovered the world of spices: their aromas when ground and the intensity of colouration and taste and freshness when added to different dishes from around the world.

The group was set up in partnership by the outreach team and Shirley Heckles, Wellbeing officer at Abingdon Mind. Abingdon Mind is an Oxfordshire mental health charity which promotes good mental health and campaigns for positive change. Oxford University Outreach team consists of Susan Griffiths and Nicola Bird who represent the Botanic Garden, Arboretum, Ashmolean, Pitt Rivers Natural History Museum and the Museum of the History of Science. The team aims to break down real or perceived barriers to visiting Oxford University museums and collections. They take the museums and collections out to groups all over Oxfordshire. To find out more, visit the outreach website http://www.museums.ox.ac.uk/drupal7/community-outreach.

Saturday, 12 July 2014

Fen Violet Project

In May of this year there were several pleasing reports in the national media that fen violet, Viola stagnina, had been recorded in the wild at Wicken Fen for the first time since 2003. This is one of only three sites known in the country, another being Otmoor near Oxford. The  Oxford Flora Group has been actively monitoring the status of this plant for several decades and hopes to establish populations in other sites in Oxfordshire. At the Botanic Garden we have been raising plants to provide material for these projects. This summer Tom Carruthers, an undergraduate in Biological Sciences from the University of Oxford, has been conducting some research on Viola stagnina:

Wild fen violet flowering on Wicken Fen, May 2014

Fen violets growing at the Botanic Garden

The last few months have seen literally hundreds of fen violets take over a corner of the Botanic Garden. These violets are part of a project I am carrying out to determine the effects of potassium on this endangered species. The project started in March, when, over one weekend, I potted 386 of the plants into pure perlite, creating a somewhat dazzling sea of white. Thankfully over the next few weeks the plants started to grow. This was a great relief as the plants had never been grown in perlite before. I had also seen a few slightly surprised looks on the faces of the staff at the gardens when I mentioned I would be growing them like this! 
By the beginning of May, the plants had grown sufficiently to cover the bright white perlite they were growing in and by the middle of May they were producing lots of their characteristic pale violet flowers. 
By this time the data collection operation was also in full swing. The purpose of the investigation is to determine the effect of high potassium levels on the plant, given there are some reports that high potassium has had a positive effect on wild populations. Because the Botanic Garden has a number of different genetic ‘lines’, I will also hopefully be able to determine the extent to which genetic variation affects their response to potassium. I am therefore busy taking measurements of the plants to see if there are differences in the timing of flower production and the ratio of sexual to asexual flowers produced. I will also take other measurements, such as the extent of seed production later in the year.
Hopefully the results from this experiment will provide valuable information to help maintain wild populations of this species in Great Britain.  
                                                                                     Tom Carruthers