Category: learning

Tea, thatch and early spring

Posted on by andy.winfield

Today as I write this the sun is shining, the birds are in full voice singing, cawing and screeching around the Garden. Bulbs are popping up, crocus are the first with daffodils a week away from carpeting the ground with yellow. Primroses are dotting grassy areas and bees are beginning to forage in the middle of the day; the minimum temperature that a bee can fly is said to be 13 degrees, so when you see one out and about you know the season is changing. In February in this part of the UK we get an extra two and a half minutes of light every day; after February and through March to June it is only two minutes. This is why a lot seems to change in February in the Garden, it is a conduit for spring; the end of January is incomparable to the beginning of March in terms of light, flower and the beginnings of warmth. We’ll still get ice, cold, wet and maybe even snow again between now and summer, but days like this make us feel that winter is nearly behind us.

Crocus appearing in the Garden.

In the Garden there are exciting changes happening. Our South African display has had the framework of a traditional African roundhouse present for much of last year; as I write this it is being thatched with a South African reed called Cape thatching reed; Thamnochortus insignis, the building will then be rendered in a red cob. These features are important for bringing context to the plants around it, being a talking point and attracting people to the Garden where they can leave with maybe a lot, maybe a little, but some new knowledge of the plant world that they didn’t have before.

Lu Yu.

Another development is our Chinese tea plantation. Yes, a tea plantation here in Bristol, just a small one but a tea plantation none the less. When landscaping the area where we’ll grow tea, visitors ask what I’m doing and seem intrigued and interested with the response. Tea is something that is in the heart of UK people, many conversations, moments of relaxation, tears and laughter have happened over a cup of tea and many millions of hands have been warmed on a mug during winter. In China tea drinking dates back 5000 years. Legend has it that Emporer Shen Nung was boiling water when leaves from a wild tree blew into his pot; he was so interested in the aroma that he drank some. He named the brew ch’a, meaning to check or investigate. Tea became integral to the culture of China when Lu Yu, a Chinese scholar, dedicated his life to the study of tea; he wrote a treatise called ‘ The Classic of Tea’ in 760CE, the earliest work dedicated to tea. Today every Chinese household will have tea brewing sets and use tea brewing as a form of welcome, celebration, in family gatherings or to apologise. We’re looking forward to planting our fifteen (so far) Camelia sinensis plants; they should be in the ground by March, which, coincidentally, is when our refreshments open again after the winter…

We look forward to seeing you in the Garden, keep your eyes on the ground and enjoy early spring!

Keeping your head above water: plants coping with waterlogging

Posted on by andy.winfield

By Helen Roberts

Flooding on the Somerset Levels.
Photo credit: Nigel Mykura [CC BY-SA 2.0],
via Wikimedia Commons

Britain has had its fair share of flooding over the last couple of years. In 2014, the Somerset Levels was under water for weeks and 2015 saw some truly devastating flooding occurring in the northwest of England. Flooding can have detrimental effects on our own lives, but also on plant communities.

Waterlogging of plants can cause chlorosis (loss of the normal green colour) of the leaves, root rot and eventually death. It’s a common problem that many gardeners face every day and there are different techniques to cope with this ever persistent problem on our shores. Precautions are even taken at the University of Bristol Botanic Garden during this wet weather.

“As far as the garden borders go, we’re very careful about never walking on them when there’s been heavy rain,” explained Andy Winfield, horticultural technician at the Botanic Garden. “If we have to get on a border for any reason, we use a board and then fork over where it was to prevent compaction and a pan forming. When a pan forms, then water is more likely to sit on the surface and create problems.”

How does waterlogging affect soils and plants?

The profile of a soil will greatly affect its interaction with water. Soils are composed of solid material with spaces filled with water, gases, roots and other living organisms – these attributes impact water retention and drainage. For example, clay soils have small pore spaces and so retain more water compared with sandy loams.

Subsoils can also influence soil structure and its interaction with water. Waterlogged soils are not only affected by the amount of water coming into the system, but by the soil’s ability to disperse and absorb that water.

When soils are waterlogged, the air spaces between the particles are filled with water and the movement of gases within the soils is inhibited preventing the roots from respiring properly. Gases such as ethylene and carbon dioxide begin to accumulate, which leads to further negative impacts on root growth. Anaerobic processes begin to changes the soil biochemistry, which leads to plant death through the build up of toxins within soils.

What is happening to plants at a cellular level when faced with anoxic or hypoxic conditions? 

When plants are waterlogged, they are not getting enough oxygen via the roots for cellular respiration and energy production. Because the plants cannot obtain oxygen via the roots, plants turn on their own energy reserves. This is much like when we use our muscles during strenuous exercise and we can’t get sufficient oxygen to the hard working cells – the cells undergo anaerobic respiration, which produces lactic acid. Plants can also undergo anaerobic respiration, but it is not sustainable and eventually, the plant dies as the demand for energy exceeds the supply.

Until recently little was known about how some plants cope with the stress of waterlogging. However, researchers from the Max Planck Institute of Molecular Plant Physiology, with colleagues from Italy and the Netherlands, have discovered a protein that triggers the activation of stress response genes when oxygen levels drop due to waterlogging. This protein is attached to the cell membrane under normal aerobic conditions, but when levels drop it detaches from the membrane and relocates to the nucleus where it switches on the stress genes. When oxygen levels return to normal, the protein degrades and the stress response genes switch off again.

How some plants have evolved to cope with anoxic and hypoxic conditions

When out walking as a child on Exmoor, I would often pick the stems of the soft rush, Juncus effusus, and peel back the green outer coating to reveal the soft, husky white pith inside. I was amazed when an adult told me this material was once used for making rush lights. The pith would be extracted from the rush leaves and combined with fat or grease to provide a source of artificial light. This pithy material is interesting though in this context as it contains a tissue called aerenchyma, which is usually found in the roots and stems of many hydrophytes (plants adapted for living in water). The tissue has large interconnected intercellular gas spaces that help to oxygenate the roots and increase buoyancy.

Other plants adapted to soggy conditions will produce fine surface roots called adventitious roots. These roots scavenge oxygen from the surface where there is a thin aerobic layer. Many of the Melaleuca species, mostly from Australia, use this way of coping with water hypoxia.

Some plants are adapted to rise above it all; they elongate their shoots to get above the water, as is the case with some floodplain Rumex species (docks and sorrels). Nymphaea species (the water lilies) – which you can see in the Botanic Garden glasshouses –  have a hugely elongated petiole, often more that two metres long, to keep their leaves and flowers at the water surface.

Arial roots (pneumatophores) of the grey mangrove
(Avicennia marina var resinifera) from South Australia.
Photo Credit: Peripitus (Own work) [GFDL, CC-BY-SA-3.0 )
or CC BY-SA 2.5-2.0-1.0 ], via Wikimedia Commons

Large tree species have also adapted their roots to cope with swamp-like conditions. These strange looking roots are known as pneumatophores – woody extensions that grow vertically upwards from the underground root system to reach above water and capture that much needed oxygen. The bald cypress, Taxodium distichum, which is found in the southern USA in lowland river floodplains and swamps, forms these roots that look like knees sticking up out of the water. The actual surface of the root is pockmarked with many lenticels, which are small stomata-like pores found in the bark that allow gaseous exchange. Other swamp and mangrove species have variations of these root adaptations to cope with low oxygen levels including pencil and cone roots (which belong to the pneumatophore group) and other types of aerial roots like knee, stilt, peg and plank roots. These roots differ in both their morphology and function, but are ultimately adapted to cope with waterlogging and often saline conditions.

The importance of wetlands as carbon sinks

Waterlogged lands are not all doom and gloom, in fact, bogginess is vitally important in terms of the Earth’s climate. Peatlands fall into that category. They act as important carbon sinks and currently cover about four per cent of the Earth’s land surface. Drainage of these areas of peatlands and wetlands for agricultural use leads to increases in greenhouse gas emissions. Researchers are actively trying to understand the effects of climate change on peatlands globally and there have been pushes to effectively  conserve and manage these precious ecosystems.

Sources:

Guillermina M. Mendiondo, Daniel J. Gibbs, Miriam Szurman-Zubrzycka, Arnd Korn, Julietta Marquez, Iwona Szarejko, Miroslaw Maluszynski, John King, Barry Axcell, Katherine Smart, Francoise Corbineau, Michael J. Holdsworth. Enhanced waterlogging tolerance in barley by manipulation of expression of the N-end rule pathway E3 ligasePROTEOLYSIS6. Plant Biotechnology Journal, 2015; DOI: 10.1111/pbi.12334

Francesco Licausi, Monika Kosmacz, Daan A. Weits, Beatrice Giuntoli, Federico M. Giorgi, Laurentius A. C. J. Voesenek, Pierdomenico Perata, Joost T. van Dongen. Oxygen sensing in plants is mediated by an N-end rule pathway for protein destabilization. Nature, 2011; DOI: 10.1038/nature10536

Daniel J. Gibbs, Seung Cho Lee, Nurulhikma Md Isa, Silvia Gramuglia, Takeshi Fukao, George W. Bassel, Cristina Sousa Correia, Françoise Corbineau, Frederica L. Theodoulou, Julia Bailey-Serres, Michael J. Holdsworth. Homeostatic response to hypoxia is regulated by the N-end rule pathway in plants. Nature, 2011; DOI: 10.1038/nature10534

Children take a ‘walk through time’ at the Bristol Botanic Garden

Posted on by andy.winfield
It’s 1 pm, the sun is shining and the volunteer guides are starting to gather near the welcome lodge in anticipation of 60 Year 4 children arriving at the Botanic Garden for a tour. It’s my son’s school, Horfield CEVC Primary School, and so I’ve decided to come along for the tour and get a glimpse into how the Garden is viewed through the eyes of eight and nine year olds.
Anne is one of the volunteer guides at the garden and she and I get chatting while we await the children’s arrival. She was a teacher for 40 years – teaching at GCSE and A levels. She laughs as she tells me she was a bit nervous she would find touring younger children challenging when she started giving these school tours at the Garden. She soon found, however, that though it was different from teaching upper level students, it was also just good fun.
Volunteer guide Tony gives a talk to Year 4 students
from Horfield CEVC Primary School prior to their tour.
“I’m not responsible for making sure they learn the curriculum, I’m here to entertain them with interesting stories about the plants we have here in the garden – to get them excited and inspired by what they see,” Anne says from a shady bench.
The guides have come prepared; they know the Horfield children have been learning about Egypt and different habitat types. As well as discussing the logistics of touring sixty children around the garden in small groups, they check in with each other about plants that might be important to point out that will link to the topics and themes they’ve been learning in the classroom.
Then the coach arrives.

A tour through the glasshouses

Before the children break into small groups to go around the garden, volunteer guide Tony gives a very brief talk about what plants need to survive. The children enthusiastically put up their hands in response to Tony’s question of what plants need to grow. Horfield Primary is lucky enough to have a garden and most of the children will have grown plants in the classroom at some stage (my son brought a runner bean home from school a few weeks back that’s doing splendidly). So, although photosynthesis hasn’t been taught by Year 4, there are other opportunities where the children are learning the basic needs and processes of plant growth.
Students have a look in the pitcher plants in the sub-tropical
zone of the glasshouses.
Baking sun and a tight schedule keeps the introductory talk brief and I follow Anne’s small group down into the glasshouses. She points out the Deadly Nightshade along the way and talks about the large black poisonous berries – a good wow factor for the kids right off the start!
In the sub-tropical zone, the children talk about the challenges of plants growing in a rainforest beneath a heavily shaded canopy and some of the adaptations they’ve made to get alternate sources of food. They have a look into the pitcher plants to see whether any wayward insects have fallen into the plant’s pitcher-shaped trap. As Anne walks by the lichen, she talks about how lightning changes the nitrogen in the air into a form that’s easier for plants to use – lichens need a continual supply of nitrogen to survive. Lightning helps feed plants? This has the children’s attention.
Having a look at the giant lily pads in the pond in the
tropical zone of the glasshouses.
In the tropical zone the giant lily pads (Victoria) impress the children immediately. Then Anne points out the papyrus that’s growing at the corner of the pond and the children quickly make the link between this plant and the papyrus paper that they’ve been learning about in their Egyptian studies. As I switch between the different groups I hear one of the other guides tell a story from Egyptian Mythology about how the Scorpion-godess, Selkis, protects the child Horus by hiding him in a papyrus thicket.
The lotus plants (Nelumbo nucifera) are also linked to Egypt as there is a Nymphaea lotus that grows in the Nile. Anne encourages the children to splash some of the pond water onto the leaves of the lotus plant and I watch as two girls are astonished at how the leaves repel the water.
Water beads off the leaf of the lotus plant.
Some of the other highlights in the tropical zone were the cocoa plant, vanilla and cotton. The Madagascar periwinkle (Catharanthus) is also pointed out for its utility in treating leukaemia.
As the children stand beside the cacti in the glasshouses, they are told that some of these plants will go 10 years without ever experiencing rainfall – longer than these children have been alive. Anne and the other guides talk about all the adaptations these plants have made to go for long periods without water.
Students are given an opportunity to experience what
happens to Mimosa plants when you touch their leaves.

Time travel through the evolutionary dell

I leave the heat of the glasshouses to join Tony’s group as they begin their walk through the evolutionary dell. Tony is telling the children about horsetails (no friend of the gardener) and pointing out the nodes of the plants. He tells them that 350 million years ago this little snippet of a plant would have been the size of a tree! The kids crane their necks up imagining and as we walk toward the tree ferns one of the girls says “It feels like time travelling!”
Tony takes the children on a walk through time in
the evolutionary dell.
Indeed it is like time travelling in the dell. In the 100 m span of the dell, we travel 200 million years from the horsetails (350 mya) to the first flowering plants (150 mya), such as the magnolia that’s on the left as you leave the dell. Surrounded by ferns, moss, horsetails, Wollemia and other conifers, the guides tell the children about how plants reproduced before the evolution of flowers and pollinators.

It’s never long enough

Somehow an hour seemed to fly by and before long the guides were rushing through the last few displays before sending the children off on their coach. As I had the opportunity to hop between the different groups I got the great sense that each group would have left the garden with a different experience as each guide has their own style and favourite stories associated with the garden. It’s never possible to see everything, but hopefully that means some of the children will encourage their parents and guardians to bring them back for another visit!
Tony holds up a horsetail and talks about plant nodes.

Linking to the curriculum

Mrs Amy Parkin, one of the Year 4 teachers at Horfield Primary, was kind enough to speak with me the next day after the tour about how tours such as this link with the classroom curriculum. This is the first time Horfield Primary has done the tour at the Botanic Garden and it was prompted by Curator Nick Wray giving a talk earlier this year to the Key Stage 2 children.
“We had two weeks where we talked about prehistoric Bristol, dinosaurs and fossils,” said Mrs Parkin. “Each class did a science trail with various outside activities and we also had speakers come in to talk to the children. Nick spoke about what plants would have been around 160 million years ago and he brought in some different species to show the children.”
As well as learning about Egypt, the Year 4 children have also covered the topic of habitats under their science curriculum and there are also cross-curricular links with their geography topic of water.
“The tour at the Botanic Garden helped extend the children’s knowledge on habitats,” said Mrs Parkin. “We focused on animals in different habitats in the classroom and in the tour we saw how plants adapt to different habitats as well.”
This tour will also give the Year 4 students a taste of what lies ahead as they will have plants as a topic in Year 5.

Talking with the students after the tour

After the tour I had a chance to speak with Megan and Henry about what they thought of the Botanic Garden. Megan said “I really liked the giant lily pads, especially since a small child could sit on one!”, while Henry really liked the giant lemon that was in the glasshouse.
When I asked Megan and Henry what the most interesting thing they learned was, Megan said she couldn’t believe that some plants can live for 10 years without water. Henry, on the other hand, learned something new about pollination, “There are lots of different bugs that pollinate plants – blowflies and beetles – and birds too!”
The Botanic Garden will run about 15 school tours during the months of June and July, with the help of their dedicated volunteer guides. These tours are in keeping with the Garden’s mission to promote education and awareness as well as to encourage and foster interest in plants within the Bristol community. In fact, the garden would like to run more school tours, so if you are involved with a local school and are interested in a trip to the Botanic Garden, please contact them via:   www.bristol.ac.uk/botanic-garden

RHS Courses: Getting practical in the garden

Posted on by andy.winfield
It’s Saturday morning at 9:30 and as I walk into the classroom there are fifteen small plates filled with different types of seeds lined up around a table. Along one of the walls, flowering plants are lined up as well. I recognise a few of the flowering plants but even then I wouldn’t know the Latin names and I recognise even fewer of the seeds. I’m incredibly glad that I’m not taking the test.
I’ve come to sit in on the RHS Level 3 course ‘Certificate in Practical Horticulture’ that is currently running at the Botanic Garden. The course has been running every Saturday from 10am until 4:30pm since the 18th of May and it will continue until the end of August.
The course is taught by a number of tutors who teach for a block of seven weeks or so and it covers core units that include collecting and testing soil samples, collecting, preparing and propagating from seed, and identifying a range of common garden plants, diseases and disorders. The course is a balance of theory and practical and so students get to practice all the skills they learn in the classroom. Today, the students will be doing some seed and plant identification and then will be going outside to do some pruning.

Life experience brings added value to RHS courses

The teacher today is Chrissy Ching, a freelance horticulturalist who has been teaching RHS courses for over six years. When Chrissy isn’t teaching and running her business, she’s also being a student herself. She’s an MSc student at the University of Bath in Conservation of Historic Gardens and Cultural Landscapes, so she’s sympathetic to the demands on adult students.
No pictures of the RHS course, but I made a quick visit to
the glasshouse to see the lotus in bloom…beautiful!
Chrissy’s first involvement with RHS courses was as a student. She was an accountant when she first started taking RHS courses. “I thought I was doing it for interest originally,” said Chrissy. However, it eventually led to a complete career change.  Many of the students taking the RHS courses are also career changers and so this added dimension of life experience that Chrissy brings to the course is added value for many of the students.
But, it’s not only Chrissy that brings life experience to the course. The students themselves come from diverse backgrounds, whether in horticulture or not, and add to the learning experience also.
“I think the students learn as much from each other as they do from me,” said Chrissy.

Teaching RHS courses at the Botanic Garden

This is Chrissy’s first time teaching an RHS course here at the University of Bristol Botanic Garden though she has taught classes a the Birmingham Botanical Gardens and numerous college and city gardens. She sees this as a wonderful opportunity for the students.
“This is a living, breathing garden with a rich diversity of plants,” said Chrissy. “This gives the students a great way to study plants and especially taxonomy.”
Of course, she also points out that because the Garden is open to the public, it also has to look attractive. Therefore, it isn’t always ideal to have unskilled students practicing horticultural skills such as pruning. Luckily, Chrissy is there to help guide the process.


Motivated by tests and inspired by previous generations

As I’m there early, I take the opportunity to speak to some of the students before the class starts. Emma is the first student to arrive. She’s a young woman with a background in graphic design. She decided to take the course for interest as she secured an allotment about six months ago and wanted to learn more about gardening. She also thought it might provide some accreditation should she wish to shift careers, ideally combining her background in graphic design with a love of gardening to eventually get into garden design. 
This is the first RHS course Emma has taken. She was allowed to enter level 3 due to her academic background, however she admits that it’s been quite demanding at times.
“I wanted to take the course as I knew the challenge of tests would motivate me and stimulate my mind,” said Emma, “and it has. There’s been more theory to the course than I thought there would be and learning all the Latin names has definitely been tricky.”
Emma was inspired to take the RHS courses by her granddad who also did RHS courses and made a career in horticulture.

Enriching an existing career 

I slide over to talk to Darren as I’ve asked Nick, the curator of the Botanic Garden, to point out someone who’s here that works in the industry.  Darren is originally from Perth, Australia and has been in the UK for around nine years. For the past nine months he’s been working for a landscape gardening company and prior to that he worked for a gardening centre.

This is Darren’s 3rd RHS course and he started taking them because he was getting lots of questions from customers at work and he wanted to have the right answers. He’s here to enrich and further his existing career. That being said, so far, Darren has footed the bill for the courses himself, not to mention the significant time commitment that’s required.
However, for Darren, the courses are well worth it. He’s been impressed by the enthusiasm and wealth of knowledge from the tutors as well as the other participants in the class.
“It’s good to have a group of people who are like-minded,” he said, “to talk about the things that you’re interested in.”
Mimosa is also in bloom in the glasshouse
right now – they’re like a little fireworks display!

Well-worth the commitment

Unfortunately I’m forced to leave the course less than an hour in. I have my five year old with me as it’s school holidays and his patience for horticulture is fairly minimal. However, what strikes me most as we jump on our bikes to spend the rest of this beautiful Saturday seeking out Gromit statues around the city, is the commitment these students have.
Most of these people have jobs, yet for nearly four months they have committed one day of their weekend to this course. Whether motivated by improved career options or by an interest in gardening, for them, this course is worth the commitment. For me as an outside observer, this speaks volumes.

If you are interested in learning more about the RHS courses taught at the Botanic Garden, please visit the website for more information.