Understanding Plants: how they tell the time and how they decide to branch

Alison Murray, Interpretation Associate in our Education Department writes about the new Understanding Plants area in the Garden

Exciting changes have been taking place in an area of the Botanic Garden to showcase some of the University’s cutting-edge plant science research and to show science in action.

Tucked away behind a hedge, the Genetics Garden once contained British crops which represented how plant breeding has improved the crops farmers grow today, and the dramatic effect of genes on plant appearance. Over the past six months, the education and horticulture teams have been working hard to transform it into a new area which aims to demonstrate current plant science in action. We’ve called this new area ‘Understanding Plants’. It will showcase some of the University’s cutting-edge plant science research. A range of new planting due to flower this summer, will explore key questions in plant science, such as: what makes a good bee plant? and what makes plants branch?

Transforming this area started last autumn. First of all, our horticultural team removed the hedge to open the area up in the hope this will entice visitors to take a look at the beds and discover a little more about plant science as they walk through the Garden.

The old Genetics Garden had previously been overshadowed by the Cuprocyparis leylandii trees on the south side of Main Walk – not exactly ideal when you are growing plants that crave sunshine. Felling these has let in more light, and allowed us to extend the beds to the south side of path. We have also changed the layout, swapping regimental rectangles for a more fluid display, in keeping with the rest of the Garden.

In April two, stunning, four metre long, curved, trellises we erected. These mark out beds which will represent research being carried out by Professor Alex Webb’s group from the Department of Plant Sciences, who are investigating how plants tell the time – known as plant circadian rhythm.

Like animals, plants have an innate 24 hour body clock. The display will reveal how sugars made during photosynthesis help synchronise and regulate the metabolic processes that keep the plant clock in time to a 24 hour rhythm. Flowering is one of the functions controlled by the plant circadian clock. Visitors can walk between the two curved beds, one growing plants that flower in the morning, and the other displaying flowers which open in the evening, or give out their scent at night. These are all rhythmic activities which the plant clock regulates by recognising what time dawn is, allowing plants to adapt to the changing day length throughout the seasons.

We have also created a 22 metre long bed which stretches in front of the line of birch trees which will be ablaze with golden sunflowers. This dramatic display will help explain how plants branch, representing research by the Sainsbury Laboratory’s Director, Professor Ottoline Leyser’s group. Every gardener knows pruning encourages branching. Professor Leyser’s group are looking at how the leading shoot makes a plant hormone called auxin, which is transported down the stem and stops other buds from growing. Chop it off and the buds below start to grow. The planting will range from dwarf cultivars like ‘Big Smile’ to the towering classic, Helianthus ‘Giant Single – all single-stemmed varieties. We will leave the flowers at each row end to grow, only cutting the tops of the plants in the middle of the bed when they are young, to discover if they will branch and demonstrate that when the leading shoot is removed, the hormone auxin in the stem drains away, allowing buds below to grow.

The Understanding Plants area will also include a new display built by our Experimental Supervisor, which will demonstrate floral symmetry and petal evolution – both key concepts in flower biology. Working out what makes flowers attractive to certain pollinators could help us plant plants which will increase the bee population.

One display will reveal how plant breeders have selected flowers with double the usual number of petals, together with naturally occurring examples of doubles. The second will explore variation in floral symmetry, which has significant influence on types of pollinators that visit particular species.

Following on from the success of our bee friendly flower mix in the Genetics Garden last year, the Botanic Garden’s Director, Professor Beverley Glover, will be investigating how attractive the scientifically informed bee mix is to bees, compared with two commercially grown mixes – one of native flowers and a standard ‘off-the- shelf’ mix. Visitors will be able to stand in a circle of wild flowers at the south west corner of the Understanding Plants area, and decide for themselves which bed attracts the most bees.

It’s an exciting time in the Garden – further updates will follow as the Understanding Plants area progresses but do come and see the changes for yourself and grasp a deeper understanding of plants.

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