Undergraduates get their first glimpse at the garden

These biology and zoology students were visiting the garden as part of their ‘Diversity of Life’ module – taking a first-hand look at some of the adaptations that have enabled plants to diversify into the more than 400,000 species that exist today. Beyond this, however, the practical offers an opportunity for the students to get to know each other and learn to work collaboratively, gain confidence in sharing knowledge,  as well as orientate themselves to this incredible resource available to them.

Nick and the demonstrators were up against time and the logistics of manoeuvring 70 students around 6 ‘work stations’. Students were split into manageable groups and two volunteer guides were brought in to assist moving the groups swiftly through the rotation of topics presented around the garden.

Off we went. As a newcomer myself, I shared the sense of wonderment and awe one student expressed as she exclaimed at how much more there was at the Garden than she had expected. She pointed out how interestingly organised the gardens were, which effectively revealed the story of plant evolution – a set-up that Nick had explained was unique to the University of Bristol Botanic Garden.

I followed a group into the glasshouses where Edith showed us the adaptations plants have evolved to cope with extreme habitats. Plants from very different families share common features that are adaptive in similar conditions. Euphorbia, for example, which grows in the deserts of Africa is so similar to the form of cacti found in the deserts of America that they are often misidentified – this is an example of convergent evolution.

The striking Haemanthus coccineus – a native of South Africa -flowers and then sets seed in autumn to coincide with the first rains, giving the seedlings a full rainy season to develop. The leaves appear well after the flowers to reduce the amount of moisture lost prior to the rains. Edith pointed out carnivorous plants that have adapted to nutrient poor habitats. She showed us a plant that produces citronella to deter insects and a species that looked half eaten to make it less attractive to herbivores.

The group was then passed along to Nick who ushered us into the tropical greenhouse to reveal further wonders, such as the orchids of Mexico that require pollination by moths to produce vanilla pods. When commercially produced in the Comoros Islands, pollination is done by hand for every flower – a task often given to children in this struggling economy. We saw the giant lily pads of Victoria cruziana. Reminiscent of triffids, Nick pointed out that in summer they have to be cut back every three days to prevent them growing out of the pond.

Nick Wray shows the students the largest seed in the world. Photo credit: Nicola Temple

Hmmm… time to escape back into the fresh air where things were growing at a more manageable pace for me, but Nick continued to show the group other commercially important plants, such as lotus, bananas and cotton. He held up a specimen of the world’s largest seed – that of the sea coconut or coco de mer (Lodoicea maldivica), which can weigh up to 30 kg.

The students were then taken into an area of the glasshouses that’s not open to the public and shown some very rare and unique plants, including Amborella trichopoda, which is of particular interest because molecular analyses suggest this is one of the earliest flowering plants. It is the last remaining species of a group that first appeared on Earth more than 140 million years ago, when dinosaurs still dominated the animal kingdom.  A sprawling shrub native to New Caledonia, Amborelladoesn’t cope with changes in humidity very well, so it is kept behind plastic to control the humidity.

Some students scribbled madly, while others just chose to listen as Nick enthusiastically explained what a unique experience this is for University of Bristol students.  ‘Until last year, Bristol was the only botanic garden in the UK growing this plant,’ said Nick. (The University of Cambridge has recently acquired one.)

In the New Zealand garden, Dave showed the radical ways plants survive difficult conditions; in this case, the attentions of the now extinct Moa bird. This was graphically illustrated by Pseudopanax, which starts off its first 10 years or so as a sapling with hard, spiky, downward facing sword-like leaves. Once considerably taller – namely beyond the reach of 3m tall Moas – the trees don’t invest as much energy into being unpalatable and transform into an unrecognisably different form, with soft and safely inaccessible leaves reaching to the light.

A group gathers around the pond to learn about angiosperm phylogeny. Photo credit: Nicola Temple

I moved on to hear about angiosperm phylogeny; a new term for me, but more exciting and less daunting than it sounds. In the past, plants were classified into family groupings based on their physical characteristics. With the advent of DNA sequencing in the last 20 years, we can use genetic relatedness to help us understand how plants have evolved. James, our demonstrator, pointed out some of the oldest species of flowering plants, including star anise (Illicium verum). This area of the garden is organised into the two major groups of flowering plants monocotyledons (seed has single embryonic leaf) and dicotyledons (seed with two embryonic leaves). The monocots include plants such as orchids and grasses, including agriculturally important species such as rice, wheat, barley and sugar cane. The more familiar garden plants, shrubs and trees, and broad-leafed flowering plants such as magnolias, roses, geraniums, and hollyhocks are dicots.

Speaking with the students, they said they enjoyed being able to touch and feel the actual plants, make comparisons and learn within this physical context. They could see as James explained how even though Protea, lotus, Banksia and London plane tree (Platanus x acerifolia) looked very different, their DNA suggests they are more closely related than they appear. Genetic relatedness is traditionally illustrated using a cladogram – a branching tree with scientific names at the end of the branches, with no sense of what these species look like. What an opportunity to see what the diversity at the end of those branches can look like!

Students use pens to see how flowers are adapted to distribute pollen on the pollinators that visit them. Photo credit: Nicola Temple

My time ran out before I could get as far as the sessions on pollination and plant evolution!  With my head spinning from this intensive and whistle-stop tour of some of the delights and extraordinary features of this garden, I sat on a bench in the autumn sunlight to reflect on the afternoon with fellow blogger, Nicola Temple, who had invited me take part in this day.

Like many of the students I spoke with as we went from location to location, I was delighted to have had the opportunity to understand the great thought behind the layout of the gardens.  There was far and away more here than I had bargained on.  I wanted to keep going but knew I could only take in so much on my first visit.  As we had gone around I had been surprised as an observer to note how quiet the students were, very few asking any questions.  Having stood back from it though I wonder if, like me, they were overwhelmed by the hidden depths to this exceptional garden. I’m certainly going to seek every opportunity to spend more time here, whether learning or simply enjoying the peaceful and stunning surroundings.

And I daresay I will come across many of the students from this day, pursuing their studies and enjoying the sheer delight and boundless wonderment that nature continues to shower upon us and that this garden so beautifully illustrates.