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Thursday, 25 May 2017

Beauty in Nature, Nature in Beauty

The 2017 University of Bristol Botanic Garden Sculpture Festival and Quilting Exhibition

By Alida Robey


Plant holder by Willa Ashworth.
Photo credit: Alida Robey
I have to confess that my expectations were low when I entered the University of Bristol Botanic Garden on Easter weekend to explore the sculpture festival. I have been to a few of these types of events over the years, none of which have done much to enhance either the setting or the ‘nicknacks’, described as art, on display.  I tend to favour simple uncluttered  gardens, focused on plants. My preconceived ideas were soon turned on their head, however, by the huge crowds queuing to get in and people milling about happily in the gardens. The right balance had been beautifully struck between fine art and very accessibly ‘buyable’ items. 

This year’s festival was the busiest yet with a record 4,729 people coming through; this annual Easter weekend event has been gaining in popularity with 2,459 people in 2013, 2,889 in 2014, 3,156 in 2015 and 3,161 in 2016. The exhibition effectively showcased the art, while at the same time drawing people through the various garden displays, with works of art that were well suited to each of the distinct areas of garden.

Large flame scallop by Philippa Macarthur.
Photo credit: Alida Robey
I spoke to several people who were all warmly enthusiastic about the whole event; helped by good weather, these visitors said they had enjoyed the atmosphere of bubbling positivity, been impressed with the creativity on display, and were thoroughly delighted in wandering through the gardens enjoying the new life bursting into leaf and flower. It was an all-round good day for people of all ages. 

I had seen a few people walking away clutching items of garden art that they had purchased.  Talking to some of the traders there, it was apparent that this had been a great success from their point of view too.  They loved being in the beautiful setting, had enjoyed seeing how the gardens had developed since previous years and were pleased at the response they had had from visitors who, if they hadn’t made purchases, often went off with contact details to follow up on at a later date.

Dish by glass artist Adele Christensen.
Photo credit: Alida Robey
One could not do justice here in print to the range and diversity of work on display. From the large shallow dishes made by Adele Christensen (see photos) with their lustrous and mysterious finish, looking like something you might find in a magical rockpool, reflecting sky and water. To the silver metal figure by Daren Greenhow, standing wistfully in a sea of anemones reaching out holding a bird perched on its hand and set beautifully at the base of a  great tree.

Ringing ceramic bells beneath the maple.
Photo credit: Alida Robey
The delightful family I joined for my tour of the exhibition drew me into things I might otherwise have missed. There was a beautiful maple tree with its new leaves unfurling above us and, as we walked under its canopy, we noticed ceramic bells suspended from its lower branches. All the family had a go at ringing the bells and their tinkling sound perfectly complemented the oriental atmosphere of the tree's form and foliage. The wonderful thing about garden art is that, in having to endure the elements, it is generally made to be quite robust and therefore also capable of surviving the curious attentions of little children.  It was a great joy to see how much the children engaged with the pieces and delighted in the garden.

Metal sculpture by Daren Greenhow.
Photo credit: Alida Robey
I had gone around the sculpture part of the exhibition, and it was almost as an after-thought that I recalled there was still the Quilting Exhibition to see.  I love quilting, but wasn’t sure I was in the frame of mind to see ‘yet another display of quilting’. How wrong could I have been? I have to say that this ended up being the highlight of my day! I had never seen it’s like. One quilter using seemingly random lines of stitching to create landscapes, another creating a beautiful and very personal quilt narrating her family's history. The latter used a technique whereby she had printed family photos and mementos of places lived into the cloth of the quilted sections. But the showstopper for me was this magnificent tableau by Jane Bjoroy called ‘True Nature’. Each exquisite creature is made by applying and appliqueing tiny pieces of different coloured cloth finely stitched. The whole scene of individual creatures was lovingly portrayed and beautifully interlinked into a stupendous portrayal of the magnificence and majesty of nature. 

I have scarcely touched the surface of the great talent that was on display throughout the Botanic Garden, and the great love that the people of Bristol clearly have for this haven of tranquillity and creativity. All I can do is use the few glimpses shown here to urge those of you who sadly missed it this year, to make sure you put the date in your diary for 2018!

Nature is an extraordinary sculptor.
Photo credit: Alida Robey
When it comes to it though, I am fundamentally a gardener at heart. It was nature as artist and sculptor extraordinaire that stays with me and which this exhibition highlighted beautifully, both in reflecting nature in art and by drawing attention to the setting.  These ferns (picture) for example, could just as readily have held their own in a sculpture gallery, to my view.

Alida Robey has a small gardening business in Bristol and attended the Botanic Garden's annual Easter Sculpture Festival for the first time this year. 

Thursday, 11 May 2017

Gardening keeps us grounded

By Helen Roberts

Sir David Attenborough once said:
Connect with Nature in any way you can. Contact with the natural world isn’t a luxury – it is actually a necessity for all of us. All we know about the natural world gives us pleasure, delight, expertise, continuous interest throughout the year – joy on many occasions and solace on sad ones. Knowing about the natural world and being in contact with it is the most precious inheritance that human beings can have.
Even containers in small spaces help make a
connection with nature. 
It is the word ‘connect’ that is so fundamentally important in a world that often feels to many people fraught, pressured and tiring. In the ever-stressful environments that humans have to confront, be it at work or home, working in gardens for many is a tonic and a way to reconnect with the landscape. For many it brings peace, a space in which to reflect and feel restored. The physicality of gardening is not only good for the body, it is good for the soul too.

This week is Mental Health Awareness Week; a campaign set up and run by the charity the Mental Health Foundation. People across the nation will get together to discuss mental health through various activities, events, talks and sharing of stories. The theme this year is ‘Surviving or Thriving’ and seeks to look at why so few people are thriving with good mental health. The lovely illustration depicting this year’s theme is rather apt, it shows a tree or shrub growing through the words ‘surviving or thriving’. Gardening undoubtedly can make you thrive on many different levels and it certainly fulfils at least 8 out of the top 10 tips listed on the charity’s website on how to look after your own mental health.

I have seen the benefits that gardening can have on mental health through my work and teaching in horticulture. It can clearly turn people’s lives around, almost like a reset button to recharge and move positively forwards. It helps to build confidence, a sense of worth and forges new friendships and all of this happening as people begin to develop a lifelong love of gardening.

Gardening keeps you active physically, but once you get the gardening ‘bug’ it is mentally energising too. Gardening is both stimulating and relaxing (unless you are digging out a tree stump) and with it comes either peacefulness if working on one’s own or, if working with others, calm chatter. Some people loathe weeding, but I know of a great many who love it either because they can just concentrate entirely on the task at hand (like a form of horticultural meditation) or they get some good thinking done. I think some of my better ideas for writing have come to me when I have been weeding.

With regards to feeding the body, gardening to grow vegetables often means you eat well and nothing tastes better than home-grown produce. I think that people are more likely to eat healthily if they know that what they are about to eat they have put the effort into producing. As a child growing up with access to a family allotment, I was much more willing to ‘try’ a vegetable if it was something that I had grown. So in that sense it makes people more adventurous in their diet and variety is good for healthy eating.

Many of us do not have gardens big enough to grow our own food, and this could be viewed as unfortunate. But as we turn to allotments and community gardens to grow food, we find opportunities to not only reconnect with the landscape, but with people with whom we share at least one shared passion. It is an opportunity to step out of the digital confines of social media and meet with people face-to-face, or at the very least, work peacefully alongside each other in silent companionship.

One of the truly great things about gardening is that it helps to remove boundaries of age, gender and background; if you have an interest in it, then the margins of society that so often leave us feeling alienated and alone are removed. I personally have gardening friends from all walks of life, ranging in age from their twenties into their eighties. Gardening definitely has no barriers and it can be refreshing to meet people who can offer a different perspective or solution on matters (maybe not even related to horticulture). If you have a passion for gardening then you will find others that feel the same. If you garden because you love doing it, then that in itself will make you feel good, both in body and in mind.

In 2013, a review of all the scientific studies of gardening-based mental health interventions found that there was convincing evidence of its benefits. There were reduced symptoms of depression and anxiety and participants described many different emotional, physical, vocational, social and spiritual benefits. In 2015, the JointCommissioning Panel for Mental Health and the Centre for Sustainable Healthcare released a guidance document for commissioners of financially, environmentally, and socially sustainable mental health services. The guidance recommends horticulture therapy as an effective, sustainable and resilient intervention to promote mental health.

Helen Roberts is a trained landscape architect with a background in plant sciences. She is a probationary member of the Garden Media Guild and a regular contributor to the University of Bristol Botanic Garden blog.

Important links:


Saturday, 29 April 2017

Mycoheterotrophs: the sly swindlers of the plant world

By Helen Roberts

New plant species are discovered all the time. But it is not typical for plants to be discovered in areas that have been meticulously surveyed. Last year, however, a thoroughly unusual species was found on an island in the Kagoshima prefecture, Japan [1].
Gastrodia kuroshimensis is a mycoheterotroph
discovered last year in Japan.
Photo credit:Kenji Suetsugu/Kobe University

Gastrodia kuroshimensis neither photosynthesises nor flowers. Certainly by no means an ornamental showstopper, it is undoubtedly odd looking with fleshy tubers, the absence of leaves and no flowers. In essence, it resembles a pathetic looking fungal protuberance. Strangely enough, it is not a fungus, but a vascular plant. The fact that it does not photosynthesise means it belongs to a peculiar group of plants that are called mycoheterotrophs, which get all or some of their nutrients from a host fungi attached to a vascular plant. The newly found species, Gastrodia kuroshimensis, is what is termed ‘fully’ mycoheterotrophic in that it depends entirely on its association with the fungus throughout its lifecycle. The relationship between it and the host fungi is not mutualistic - it takes all it needs while offering nothing in return. In other words, it’s a big fat cheat.

Mycoheterotrophs parasitise fungi, which are in turn getting their nutrients from a host plant. The fungi that are preyed upon by these cheaters are usually mychorrizal fungi, with mycoheterotrophs often parasitizing a specific arbuscular mycorrhiza (arbuscular mycorrhiza are those that penetrate the cortical cells of plant roots). In this sense, they are dissimilar to parasitic plants like dodder, which obtain their nutrients by directly taking what they need from the vascular tissue using an adapted root.

Who wants flowers?


The second interesting thing about Gastrodia kuroshimensis is that it is entirely cleistogamous, producing flowers that never blossom. Most plants also produce chasmogamous (cross-pollinating) flowers; it is extremely rare to find plants that are entirely cleistogamous. The term cleistogamy means ‘closed marriage’ and the plant produces flowers that are self-fertilised within closed buds. It is essentially a way of ensuring reproduction [2].

The evolutionary reasons are still a puzzle, but it is considered a way of safeguarding fertilisation if suitable pollinators are not around or they have somehow missed the plant or if environmental conditions are not conducive. It can also aid plants in adapting to local habitats, where both sets of maternal genes are passed onto the progeny, thereby removing harmful gene variants. Being cleistogamous also use fewer resources; flowers that are chasmogamous require more energy to produce. However, in most cases chasmogamous flowers are beneficial as they help to provide variability necessary for adaptation, hybrid vigour and negate the effects of deleterious mutations. The reasons for complete cleistogamy remain unresolved but the discovery of Gastrodia kuroshimensis may well help to answer some of these questions.

Other fungi tricksters


Other plants that fall under the mycoheterotrophic category are orchids, monotropes (a subfamily of Ericaceae), members of the Gentian family, certain liverworts and the gametophyte stages of ferns and clubmosses. Some are quite attractive if you like the look of fungal fleshy looking vascular plants with varying hues of red, white and cream. Some are even striped red and white and so commonly known as candystick. Whatever their appearance though, they are unquestionably interesting. But because or their size and rarity they often go unnoticed, lingering in the background like villainous free-loaders.

Mycoheterotrophs at the University of Bristol Botanic Garden
The inflorescences of toothwort in the pollinator display
this week at the Botanic Garden.
Photo credit: Andy Winfield


A wonderful example of a mycoheterotroph at the Botanic Garden is toothwort (Lathraea squamaria L.). It spends most of its time below ground, but in April it sends up aerial inflorescences about 20-25 cm tall. These were in their full glory in the garden a couple of weeks ago, but can still be seen (see photo) in both the pollinator display on the left as you walk in the main gate, or at the east gate.

Unlike Gastrodia kuroshimensis, toothwort flowers are bisexual and pollinated by bumble-bees.

Stop in over the weekend if you get a chance and have a look at this interesting plant.

Helen Roberts is a trained landscape architect with a background in plant sciences. She is a probationary member of the Garden Media Guild and a regular contributor to the University of Bristol Botanic Garden blog.

Sources:

[1] Kobe University. (2016). Plant discovered that neither photosynthesizes nor blooms.
< https://www.sciencedaily.com/releases/2016/10/161014092115.htm>

[2] Allaby, M. (2016). Plant Love: The scandalous truth about the sex life of plants. Filbert Press, pp. 98-103.



Friday, 31 March 2017

In the guts of bees

By Nicola Temple

We hear a great deal about the beneficial bacteria that live in our digestive system and commonly referred to as the microbiome, which help us turn indigestible materials into nutrients that we can absorb. There are countless probiotic products on the market that are meant to introduce more of these beneficial bacteria into our system, enriching our microbiome. However, humans and indeed mammals are not alone in having helpful microflora in the gut.

The microbes that inhabit the guts of social bees has been of particular interest recently. These microbial communities have been studied for their role in bee health, but also as a model organism to help understand the relationship between hosts and their gut microbes, potentially providing insight into our own system.

The specialised cast of microbes

The microbiome of bees is relatively simple, but very specialised. There are about eight to ten bacterial species, but different species of bee will carry different strains of these bacterial species. The bacteria are so specialised that a strain from one bee genus isn’t able to colonise the gut of a bee from a different genus. This suggests that these bacterial strains have been evolving with their hosts over a very long period of time.

Nest entrance of the stingless bee, Geniotrigona thoracica, is
from Malaysia. Photo credit: Eunice Soh.
Like us, these bacteria help the bees break down complex molecules through fermentation in order to make the nutrients available to the hosts. There’s also evidence that they might help to neutralise toxins in the gut. These friendly microbes also outcompete nastier pathogenic species that can make the host ill. For example, the gut microbes in bumblebees have been linked to lower levels of the parasite Crithidia bombi.

The gut microbes of non-social insects, including solitary bees, aren’t as specialised because they acquire them from their environment rather than from other members of their species. Among social bees, it is behaviours such as passing food between individuals and feeding larvae, that allow an exchange of microbes. However, these exchanges pass along the bad microbes as well as the good.  Beekeepers are painfully aware that pathogens can pass through a colony like wildfire. Social insects therefore need a very responsive system that helps keep these pathogens in check. And the key to this might be a very ancient relationship between the good microbes and the host bees themselves, which allows the bee’s immune system to quickly identify the less desirable critters.

A long-term relationship

Research published this week in the journal Science Advances suggests that five of the species of gut bacteria found in modern social bees have been evolving along with their hosts for about 80 million years. It was around this time that the first solitary bees began socialising with other bees - sharing nests and food resources and making concerted defence efforts. The descendants of these first social bees are the hundreds of species of honey bees, bumblebees and stingless bees that are alive today.
This finding not only shows that social creatures, such as bees and humans, transfer bacteria among each other during the same lifetime, they pass them along generations, enabling the microbiome and host to evolve together.

"The fact that these bacteria have been with the bees for so long says that they are a key part of the biology of social bees," says Nancy Moran, a professor of integrative biology at the University of Texas who co-led the research with postdoctoral researcher Waldan Kwong. "And it suggests that disrupting the microbiome, through antibiotics or other kinds of stress, could cause health problems."
The co-evolution of the gut bacteria and the bees is so closely linked, in fact, that the researchers found that when a new species of bee branches off in the evolutionary tree, a new strain of bacteria branches off with it. The result being that each of the hundreds of species of social bees alive today has its own specialised strains of gut microbes.

Human influence on this long-term relationship

It’s currently unknown how toxins introduced by humans, including pesticides, might affect the bee microbiome. There is recent evidence, however, that the prophylactic use of antibiotics by bee keepers in the US has resulted in some gut bacteria in honeybees developing antibiotic resistance.


References

Engel, P. et al. 2016. The bee microbiome: impact on bee health and model for evolution and ecology of host-microbe interactions. mBio 7 (2): e02164-15.

Kwong, W.K., Medina, L.A., Koch, H., Sing, K-W., Soh, E.J.Y., Ascher, J.S., Jaffe, R. & Moran, N.A. 2017. Dynamic microbiome evolution in social bees. Science Advances 3: e1600513.

Kwong, W.K., Engel, P., Koch, H. & Moran, N.A. 2014. Genomics and host specialization of honey bee and bumble bee gut symbionts. PNAS 111 (31): 11509-14.


Tuesday, 14 March 2017

Look out for the early bumblebee...they’re emerging now!

By Alida Robey

I am always so impressed and uplifted when I see the first bees out, braving the cold and wind to forage in the spring sunshine. The buff-tailed bumblebee (Bombus terrestris) braves the winter, emerging on fine winter days to forage, but another species that you are likely to see right now is the ‘early bumblebee’ or Bombus pratorum.

The early bumblebee (Bombus pratorum).
Photo credit: S. Rae [via Flickr CC by 2.0]

How to tell one stripy buzzing creature from another

Being larger and hairier than honey bees, bumblebees in general have a bit more protection to cope with colder weather conditions, giving them an advantage when it comes to foraging in the early spring. The early bumblebee is common throughout Britain from March until June or July, and in milder parts of the south of England, as early as February.

The Bumblebee Conservation Trust has a very good identification chart and video guide to help distinguish different bumblebee species. When trying to distinguish between species of bee, size, tail colour and stripes are the features to look at. Bombus pratorum is noticeably smaller in size than other bee foragers at work in the spring. Queens, workers and males have a yellow band on the thorax and abdomen, though the band across the abdomen is less obvious or sometimes absent in workers.

The tail is a strikingly dark orange-red, but can be tricky to see as this colouring is only in the final tail section and may also fade with time. Males have a broad yellow collar that wraps around the thorax, and yellow hair on the face.

The bee’s choice of diet

The early bumblebee is a  good pollinator of flowers and fruit, enjoying in particular white clover, thistles, sage, lavender, Asteraceae, cotoneaster, alliums and a range of daisy type flowers; it is also an important pollinator of soft fruit, such as raspberries and blackberries.


Habitat and lifecycle 

B. pratorum’s nesting period is shorter than other bumblebees at just 14 weeks. Queens are fertilised in late summer and then usually go into hibernation. They will emerge from hibernation between March and May depending on the climate in that location and find a place to make their nest. However, because of their short nesting period, they can have two or even three colonies a year in the warmer, southern regions of the UK; new queens mate and, instead of hibernating, immediately start a nest.

At the start of a colony cycle, the queen has a large store of food, which allows her to start laying her eggs to produce workers and foragers who will then gather all the supplies she needs in order to remain in the nest and continue to lay eggs. As the colony cycle nears its end, she will produce more queens before dying herself, allowing the young queens to take up the cycle for the next spring. These young queens will go out to forage for themselves and return to the nest for shelter, but they don’t contribute to the dying colony. When they are ready to mate, the young queens follow the scent of chemical attractants deposited by males. The old colony dies off, with B. pratorum rarely seen after July in the UK,  and so the cycle continues for another season.

The early bumblebee is known for nesting in unusual places such as abandoned bird boxes or rodent nests or just under the ground. Colonies are small at less than 100 workers.


Cuckoos

The bumblebee is no more immune than other creatures to being taken advantage of. Of the 24 bumblebee species in the UK, 6 are ‘cuckoo bees’, which don’t make their own nests, but rather kill off the queen in another nest and get the worker bees to raise her larvae. It is the species Bombus sylvestris, which is a nest parasite of the early bumblebee.

Buzz Pollination

I was intrigued to hear this term, describing a process unique to bees, whereby they catch hold of a flower and by emitting a high pitched buzz shake free the pollen trapped inside (watch a video here). I had also often wondered if bees had any way of knowing whether others had raided the pollen stores before them. It turns out that they have smelly feet that leave a distinctive odour on flowers, which indicates to other bees that the supplies have been raided.


What can we do to help?

As you will know, our pollinators are in decline not just in the UK, but globally.  I was saddened to learn that two species of bumblebee have become extinct in the UK since 1900 - Cullums bumblebee (Bombus cullumanus) and the short-haired bumblebee (Bombus subterraneus). Having lost 97% of wildflower-rich grasslands, we can take action to plant the flowers that are rich in pollen and nectar and therefore of most benefit to bees – some flowers, like pansies, and most double flowers may look pretty, but are of little benefit to bees.

Then there is the whole issue of pesticides. Neonicotinoids, used in some pesticides, are lethally toxic and infiltrate every aspect of the plants systemically - one teaspoon of neonicotinoids is enough to give a lethal dose to one and a quarter billion bees. Professor Dave Goulson, Professor of Biology at the University of Sussex and a bee expert, has been on a mission to see how widespread the use of these pesticides are as plants with a ‘Bee-friendly’ label may have been treated with these pesticides before being put on the shelves of the plant nursery.

Splitting and sharing plants and growing from seed can help ensure the plant hasn’t been exposed to these pesticides - it’s another thing we can do as gardeners to help these valiant and much-assailed vital workers in the garden. Also, as a Friend of the University of Bristol Botanic Garden, you have a unique opportunity to grow special plants from seed collected at the garden!

Another fun way you can help is to take part in The Great British Bee Count using an app developed by Friends of the Earth and which will be running again this year from 19 May – 30 June 2017. This is an initiative to help monitor the numbers of the different bee species found in the UK.  You can see the results of last year’s survey and access various educational resources on their website.

Alida Robey has a small gardening business in Bristol. For several years in New Zealand she worked with others to support projects to establish composting on both domestic and a ‘city-to-farm’ basis.

Friday, 24 February 2017

Sowing Victoria

By Nicola Temple

A photo taken a couple of years ago - I
have a grasp on my son as he leans
over into the tropical pool to get a
good look. Victoria cruziana is in flower
as is the lotus above us.
Photo credit: Shelby Temple
For me, one of the highlights at the University of Bristol Botanic Garden is the giant waterlily (Victoria cruziana) that lives in the pond in the tropical glass house. Its enormous leaves, which can reach 2 metres in diameter, are studded with spines on the underside and always provide ample wow factor for visiting children (my own included).  

The plant is found in slow moving waterways in Brazil, Argentina, Paraguay and Bolivia - in places such as the Pantanal. Its pollination story is an interesting one in that it is pollinated by a beetle (Cyclocephata castaneal). Its white flowers give off a strong scent that attracts the beetles in the evening. The flower then closes around the beetles, trapping them in the flower overnight. The flower produces heat (thermogenesis), raising the temperature as much as 9oC above the ambient temperature outside, which means the beetles can maintain a high level of activity without using as much energy. It’s a thermal reward and the plant benefits as the active beetles will pollinate the flower. The pollinated flower opens the next evening, revealing a new light pink colouration to its petals. The beetles flee the flower and make their way to the next unpollinated flower.

Of course, this species of beetle isn’t found in the Botanic Garden, which makes pollination a bit more challenging. However, there are other insects in the Garden that have filled this niche and the plants have set seed over the last few years. However, this is the first year that staff at the Botanic Garden have tried to sow this seed and, so far, things are going well!
The seeds of Victoria cruziana are kept wet.
Photo credit: Andy Winfield

Replicating the natural environment

In its natural environment, the seeds from Victoria cruziana would be buried in the sediments, stirred up perhaps by grazing capybara and swirling river currents. It wouldn’t be until the high water levels following the rainy season had receded that the water temperature and the amount of light penetrating to the sediments beneath would be sufficient to prompt germination.

In the Botanic Garden, botanical horticulturist, Andy Winfield, first primed the seeds by scratching the tough seed coat with secateurs. The seeds were then sown into topsoil and covered with a layer of horticultural grit. The pots with the sown seeds were then placed in a container of water to a level about 10 cm depth above the seed. This replicates the approximate water depth in the natural environment. The water is heated to a temperature of between 30oC and 32oC; this is critical to start the germination process.

Andy scores the seeds with secateurs
before sowing.
Photo credit: Nicola Rathbone
Victoria cruziana grows around the edges of water bodies and in wetland areas where there is no forest canopy. In order to replicate the amount of daily sun it would be receiving in the tropics and sub-tropics, grow lights on a 12h on/12h off cycle were hung above the pots. Then the whole contraption was covered in plastic film to reduce evaporation and maintain humidity.

Andy had read that germination time is generally about 2-3 weeks in this type of scenario, but within a few days he noticed that the seeds were starting to send out roots and when I visited a week after sowing, the hypocotyledonous stems were clearly emerging from the seeds and shooting upwards toward the surface of the water. 


Preparing to plant Victoria out

At the moment, the water temperature in the pool in the tropical glasshouse is only about 14oC, far too chilly for Victoria. In the coming weeks, however, these plants are
likely to grow quite quickly. Andy and the rest of the team at the Garden will pot them on several
times, gradually reducing their water temperature. At the same time, Bristol temperatures will be increasing and the tropical glasshouse will start getting warmer, as will the pool. By the time the Victoria plants have a few decent leaves, the temperatures between the tropical pool and the plants will have become similar enough that Victoria can be put into the planters in the pond.

The annual light intensity here in Bristol is considerably less than Victoria cruziana would receive in South America. However, the long summer days here mean that during those months more solar radiation is received here in a single day than in tropical South America. This helps Victoria cruziana flourish in the Botanic Garden tropical pool over the summer and it will be worth a visit to see it in flower. See the series of photos below taken the day the seeds were sown.
Andy prepares the loamy mix for sowing.
Photo credit: Nicola Rathbone

The seeds are sown into a loamy mix.
Photo credit: Nicola Rathbone

The soil is covered with a horticultural grit.
Photo credit: Nicola Rathbone

The seeds are sown and are ready for immersion
in a nice warm bath.
Photo credit: Andy Winfield
The pots immersed in the warm bath.
Photo credit: Nicola Temple
Only one week after sowing, the embryonic stem
has emerged and is stretching for the surface.
Photo credit: Nicola Temple

Sources:

Seymour, R.S. and Matthews, P.G.D. 2006. The role of thermogenesis in the pollination biology of the Amazon waterlily 
     Victoria amazonica. Annals of Botany 98(6): 1129-35.

Tuesday, 14 February 2017

A portrait of a boy and his plant

By Nicola Temple

On the 12th of February 1809, Charles Darwin was born in a large Georgian house, known as The Mount, in Shrewsbury. As a biologist, I am very familiar with the works of Darwin. And when I conjure an image of this man in my head it is of him in his 60s, bald on top and with a formidable beard. However, on a recent visit to the University of Bristol Botanic Garden, the curator, Nick Wray, showed me a portrait I had never seen before.

The portrait was completed in 1816, just before Darwin turned 7 years old and he is with his sister Catherine. It is a magnificent piece done using chalk on paper, by the artist Ellen Wallace Sharples (1769-1849), who was settled in Bristol at the time - not far from the Botanic Garden in Clifton [see note 1].

Nick pointed the portrait out to me because he is interested in the plant that Darwin is holding in the portrait. Children would have often been given something to hold while sitting for a portrait - it gave them something to do with their hands to prevent fidgeting. While Catherine has a posy of flowers in her hand, Charles is holding a clay pan on his knee with a plant in full bloom. This would have been no small feat for a child.
The portrait painted by Ellen Wallace Sharples in 1816
of Charles and Catherine Darwin.

Nick recognised the plant held by Darwin as almost certainly Lachenalia aloides (the opal flower), which is a native to the Western Cape of South Africa. Nick informed me that Cape flora were very in vogue during this period. The collecting activities and botanical observations of horticulturist-explorers, such as W. Paterson, Francis Masson, Robert Gordon, W.H.C. Lichtenstein, John Barrow and William Burchell, created a voracious appetite among Europeans for the curious plants of the Western Cape, while established trade routes enabled their transport back to Europe. So it is very likely that the children of a wealthy family would have been given such exotic pieces to hold rather than a favourite toy.

The artist almost certainly painted the portrait at the Darwin’s family home, The Mount. Records show that their impressive house had equally impressive gardens, including a conservatory and hothouse. The Lachenalia aloides likely came from one of their own glasshouses. Grown correctly in a cool frost free glasshouse, this little plant flowers from February-March. In a warm glasshouse it would flower earlier.

In an article written for the Garden History Society by Susan Campbell (Vol. 40, No 2 Winter 2012), she lists the plants cultivated at the Mount, including those growing in the Conservatory and Hothouse. In these lists, one species of Lachenalia is mentioned, Lachenalia pendula, which is now known as Lachenalia bulbifera. This species is almost always red in colour with the robust flower spike leaning to one side. However, yellow tipped orange forms have been recorded in the wild. Whether the plant in the portrait was misidentified in the original plant list or it was correct and an unusual orange and yellow form was cultivated, we shall never know. On examining the portrait carefully, its habit, erect inflorescence and the colour of the flowers, suggests the plant was wrongly identified and should be Lachenalia aloides. Nick goes onto suggest that, “the presence of this Cape bulb flowering in this portrait is evidence that the chalk picture was made around the 12 February 1816, Charles Darwin’s seventh birthday. The picture may have been commissioned deliberately to commemorate the occasion”.

About Lachenalia aloides

There are about 110 different species of Lachenalia, 80 of which are found in the Cape region of South Africa. L. aloides has a number of different varieties, all of which grow on granite or sandstone outcrops. The flowers can vary quite a bit in their colour. Some plants have flowers that are nearly entirely yellow, while others are magenta at the base turning yellow and then to green.

The Lachenalia genus are geophytes, which means that they spend part of the year dormant as a fleshy underground structure, such as a bulb, rhizome or tuber. South Africa is a global hotspot of geophyte diversity. There are 2,100 species across 20 different families in the area and 84% of them are endemic.

Lachenalia aloides is naturally pollinated by sunbirds, which use their long curved bill to access the nectar at the base of the tubular flowers. It was widely-thought until fairly recently that sunbird-pollinated plants had almost always evolved perch-like structures to make feeding for the sunbird easier. However, L. aloides has no such structure and the sunbirds simply sit on the ground to feed on the flowers - an observation that has been made with other low-growing sunbird-pollinated species.

Lachenalia in the Botanic Garden

Lachenalia aloides is in bloom at the
Botanic Garden right now if you want to
have a look at this interesting South African bulb.
The Botanic Garden has some specimens of Lachenalia aloides and other Lachenalia species in the glasshouses and, much like the plant Darwin is holding in the portrait, they are currently in bloom. The portrait would have been painted around this time of year, when there would have been very few plants in bloom. This further supports Nick’s conclusion regarding the species.

The Lachenalia story was one aspect of a lecture titled The Origin & Diversity of Flowering Plants, which was given recently by Nick Wray to the members of the annual Darwin Festival, held each February in Shrewsbury. The audience, made up of academics, ecologists, naturalists and keen amateur and professional gardeners, were taken through the flower pollination syndromes, illustrating the diversity that has evolved over millions of years. Nick discussed the work of the Angiosperm Phylogeny Group (APG) work, the planting of the APG III displays at the Botanic Garden and the difficult task of cultivating Amborella trichopoda and its place at the base of the extant living Angiosperm phylogenetic tree. The talk was illustrated by plants that were brought from the Botanic Garden. This created a lot of interest and added to the sense of place as the talk was held in the Shrewsbury Unitarian Church where Darwin’s mother took him and her other children to worship until Charles was thirteen. When, with an eye to his future university life, Darwin would have to attend a Church of England Church to ensure he would be eligible for a university course as students from Unitarian families would not be admitted.

The group were very appreciative of Nick’s talk and plan to make a summer visit to the Botanic Garden to enjoy the garden and explore its various evolution displays.

Notes:

1. Ellen Wallace Sharples met her husband in Bath where he was her tutor. After they married, the couple travelled back and forth a couple of times between England and America. When Ellen’s husband died in 1810, she moved to an apartment in Clifton with her two children (also artists) in 1811. She made her living doing portraits, as did her children. When she died in 1849, she left a substantial sum to the Bristol Academy which was instrumental in financing Bristol's first art gallery, now the Royal West of England Academy.

Sources:

Campbell, S. 2009. ‘Sowed for Mr C.D’: The Darwin family’s garden diary for The Mount, Shrewsbury, 1838-65. Garden 
     History 37 (2): 1-16.
Campbell, S. 2012. ‘Its situation...was equisite in the extreme’: ornamental flowers, shrubs and trees in the Darwin 
     family’s garden at The Mount, Shrewsbury, 1838-65. Garden History 40 (2): 1-32.
Procheş, Ş., Cowling, R.M., Goldblatt, P., Manning, J.C., Snijman, D.A. 2006. An overview of the Cape geophytes. 
     Biological Journal of the Linnean Society 87: 27-43.
Turner, R.C., Midgley, J.J. 2016. Sunbird-pollination in the geoflorous species Hyobanch sanguinea (Orobanchaceae) 
     and Lachenalia luteola (Hyacinthaceae). South African Journal of Botany 102: 186-9.


Friday, 3 February 2017

Bumblebees who brave the winter

By Nicola Temple

This past weekend, my family and I met with friends in the village of Shipham, in Somerset, for a walk. It was torrential rain, yet we were determined. We dressed ourselves and three children under the age of 10 in waterproofs and set out. We arrived at a local country pub, not more than 3 km away, resembling drowned rats. And as a Canadian living here in the UK, I still marvel at the fact that nobody took one bit of notice at the state of us. It’s what you do. You get wet. You find a pub. You hunker down for a hot Sunday lunch. And you hope it tapers off before you have to head out again. (It didn’t.)

Pollinators, at least of the flying insect variety, aren’t terribly keen on this kind of weather either. Most hunker down for the winter months as there is generally not a lot of nectar to forage this time of year anyway. How they do this depends on the species. Honeybees reduce the colony to a minimal size and rely on their honey stores to see them through, while they dance in order to regulate the temperature of the hive. Most bumblebee colonies die out completely and the queens that mated at the end of the season find a place to hibernate. Solitary bees may hibernate as adults or as larvae, emerging only when the weather conditions are suitable. To each their own.

Martin Cooper spotted this buff-tailed bumblebee queen
foraging on his Mahonia flowers in Ipswich on a sunny
January day in 2015.
Photo credit: Martin Cooper [via Flickr CC]
However, there is one flying pollinator that can be spotted this time of year here in Bristol, and indeed, other warmer regions of the UK. It is the common buff-tailed bumblebee (Bombus terrestris). This species was first spotted during the winter of 1990, in Exeter. Sightings have been increasing ever since and include nest-founding queens, workers and males, suggesting this is a winter generation of the species.

The mated queen will emerge from her subterranean dormant state (diapause) during warm winter weather and set about establishing a new colony. The potential cost of waking up early is that the warm weather could be short-lived and temperatures could plummet. The benefit, of course, is that there’s nobody to compete with for food. If successful, the queen can establish a colony before the other pollinators even wake up from their winter nap.

Introduced plants provide winter forage

Of course, there is potentially another cost to emerging early - there could be nothing to eat. Bees are able to forage at temperatures around 0oC, but if there aren’t enough plants in flower, they won’t find the pollen and nectar needed to sustain the colony. Few native UK species flower in winter, but species introduced by avid gardeners to bring some winter colour to the garden, also bring some much-needed food to the buff-tailed bumblebee.

Researchers at Queen Mary University of London and The London Natural History Society, conducted a study of buff-tailed bumblebees foraging in London parks and gardens during winter about ten years ago. They wanted to see just how much food the bees were finding as food is directly related to the success of the colony.

The researchers found that there was plenty of forage to sustain the colonies and, in fact, the foraging rates they recorded near the end of winter were equivalent to peak foraging rates found in the height of summer. This doesn’t mean that the winter-flowering plants, such as the evergreen shrubs of the Mahonia spp., are providing more pollen and nectar than all the plants in the height of summer. But it does mean that each flower might have more pollen and nectar available because there aren’t other pollinators out and about also using the resource. The bumblebees, therefore, don’t need to go as far to find an equivalent amount of food and so they can collect it at a faster rate.  

Strategies for tolerating cold

Buff-tailed bumblebees aren’t as tolerant to cold as some other bee species; workers will freeze solid at about -7.1oC while queens freeze at -7.4oC. The bumblebees can obviously find warmth in the colony, but they need to forage and therefore be able to tolerate short spells of cold during the winter months. They may even need to tolerate cold temperatures for up to 24 hours as bumblebees often overnight away from the colony when they are unable to return from foraging.

Researchers from the University of Birmingham looked at the different cold tolerances of this bumblebee species a few years ago. They found that 50% of workers died after being exposed to 0oC for 7.2 days while queens could last over 25 days at this temperature - likely due to their fat reserves. However, as the forage study showed, the bees seem capable of finding food sources closer to the colony during winter months, which may reduce the likelihood of them having to endure cold temperatures for a lethal period of time.

These bumblebees may also have adopted some strategies to help reduce their possibilities of freezing. Pollen is an ice-nucleating agent in that it promotes the development of ice at higher temperatures. Other insects have been observed to expel any ice-nucleating agents from their gut when they experience low temperatures to avoid freezing. While this wasn’t observed in the bumblebees, it is a strategy that individuals might employ when caught out in the cold.

The more frequent observation of buff-tailed bumblebees in winter is thought to be a result of warmer autumn temperatures brought about by climate change. In a study from 1969, researchers reported a 6-9 month dormancy of all bumblebees in southern UK, so in a relatively short period of time there has been a considerable change in their seasonal pattern. There seems to be some flexibility in these patterns among bumblebees and for now, establishing winter colonies seems to be working for the buff-tails. However, with so many of our pollinators under threat, there is obviously also concern among the scientific community that more frequent extreme weather events could also spell disaster for these colonies that have selected to brave the winter months. As gardeners, we can perhaps do our bit by planting some winter forage species.

This year, the University of Bristol Botanic Garden will embrace a pollinator theme, with the aim of highlighting some of the lesser-known pollinators that are so important here in the UK. We love our pollinators, but research is still revealing so much about their unique and complex relationships with plants. So watch this space as we share some of these wonderful stories through our blog. We will also be posting pictures of pollinators we see in the Botanic Garden on our Twitter feed and Facebook page. But to see these pollinators in action, take some time to visit the Botanic Garden. Make space in your busy schedule to watch nature at its best - it’s worth it.

Sources:

Alford DV (1969) A study of the hibernation of bumblebees (Hymenoptera: Bombidae) in Southern England. Journal of 
     Animal Ecology 38: 149-170.
Owen EL, Bale JS, Hayward SAL (2013) Can winter-active bumblebees survive the cold? Assessing the cold tolerance of 
     Bombus terrestris audax and the effects of pollen feeding. PLoS ONE 8(11): e80061.          
     doi:10.1371/journal.pone.0080061
Stelzer RJ, Chitka L, Carlton M, Ings TC (2010) Winter active bumblebees (Bombus terrestris) achieve high foraging 
     rates in urban Britain. PLoS ONE 5(3): e9559. doi: 10.1371/journal.pone.0009559