Category Archives: John Tweedie

Something for Blue Monday – the only known blue flowered asclepiad

Tweedia caerulea - OBG 2014-11-06 11.33.14

Today is Blue Monday – reckoned to be the most depressing day of the year, though I’m in a very good mood: just back from a great 9am seminar with my final year students taking the Biodiversity & Conservation module.  They presented some really interesting, diverse and thought provoking papers as part of their assessment for this module; it’s a great group to teach.

But if you are suffering from the blues this morning, here is a photograph to cheer you up.  As far as I am aware Tweedia caerulea (also known as Oxypetalum coeruleum)  is the only known blue flowered asclepiad (that’s to say, a member of the family Apocynaceae subfamily Asclepiadoideae – what used to be the family Asclepiadaceae*).

No one is sure why blue is such a rare colour within the asclepiads (and indeed the Apocynaceae as a whole) and it may be connected to the pollination system of this plant.  However we don’t know what pollinates Tweedia caerulea in the wild so it’s hard to test that idea; other species within this group are variously pollinated by wasps, bees, flies, moths, etc.  Truly blue flowers (as opposed to some shade of purple or violet) are relatively uncommon generally amongst the flowering plants and the source of much interest and excitement in those groups where they do occur, for example the Himalayan Poppies (Meconopsis).

Tweedia caerulea is easy to grow from seed but not so easy to get through the winter in the UK, so in the past I’ve grown it as an annual in the garden.  Apart from the colour, one of the other reasons I like this plant is that it’s named after the 19th century plant collector John Tweedie whose life I’ve been researching over the past 20 years or so – see this paper for example.



*The asclepiads are my favourite group of plants, and one that I’ve published quite a bit of research on, so I was a bit miffed when the taxonomic rank of the family was relegated to subfamily.  But it makes evolutionary sense and now gives me a much larger family of plants on which to research, so every cloud etc. etc.

Budget cuts to Kew are cultural vandalism



The Royal Botanic Gardens, Kew, is a beautiful place to visit, a tourist destination for visitors to London, and a green island in an urban ocean.  That’s the public face of the Gardens.  What is less well appreciated to most of the casual strollers around the flower beds and glasshouses, is that Kew is arguably the most important centre for botanical research anywhere in the world.  During its long history it has produced, and continues to deliver, top rate science that informs international conservation strategies, agriculture and horticulture, as well as basic plant science in ecology and evolutionary biology.

It’s also a welcoming, inclusive place that embraces scientific visitors from all over the world, as I know from personal experience.  Although I’ve never had a formal relationship with staff at Kew, I’ve benefitted enormously from informal links, which have facilitated research and teaching, including annual trips to the Kew Herbarium for my final year undergraduate students.

I first visited Kew as a naive 20 year old to look at their living plant collection during research for what became my first ever publication: “Adaptations to arid environments in the Asclepiadaceae” (British Cactus and Succulent Journal 1986).  So started a long appreciation of Kew and what it freely offers teachers and researchers, which has included access to specimens prior to overseas research trips, to assess distribution and flowering times; identification of specimens we’ve collected on those trips; and primary data for our study of fly pollination in the genus Ceropegia.  I’ve also used their archives for my work on John Tweedie.  Kew is an incredible resource that, in any civilised and culturally aware country, would be cherished and supported. Unfortunately it appears that I do not live in such a country.

Rumours have been circulating for a while about an impending, massive budget cut at Kew, on top of financial savings that have already been made.  Now it appears that those proposed cuts are  much bigger than anyone had thought and 120 posts, mainly in science, are threatened.  I won’t repeat the depressing statistics underlying all of this – I’ll just urge you to visit the online campaign against these cuts, read the details, watch the David Attenborough video, sign the petition, and share it with friends and colleagues.

Please don’t let Kew wither away; it’s too important to UK science, conservation and education to allow it to be gutted without a fight.



It’s called rainforest for a reason, right? Brazil Diary 6

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Tropical rainforest is not glamorous.  The sanitised, technicolour, televisual view of rainforest that we see in nature documentaries, of whizzing butterflies, flash-dancing birds, and flamboyant flowers, presents only part of the story.  Rainforest is dirty, wet, and it smells, of mould and mud, and dead leaves and flowers, and rotting wood.  By day it hums and chimes and fizzes with a thousand animal conversations, and green dominates all: colour is as rare as it is welcome.  By night those conversations, of insects, frogs, mammals, and birds, increase one hundred-fold.  With the night come also the insects (silent or whining) that bite and suck your blood, while above your head in the roof space of your bedroom, bats awaken and chirp and scuttle, flitting out to hunt.

Always, day and night, there is water in the form of rivers, streams, ponds, and pools.  And rain; or the threat of rain; or the aftermath of rain.  For the four days we have spent in Santa Virginia field station in the Serra do Mar state park it has rained every day, all day, all night.  It’s called rainforest for a reason, right?

For the persistent habitué of the rainforest, nothing remains dry for long, clothes and bedding are constantly damp, wood and leather obtains a greyish grape-bloom.  It is a difficult environment in which to live and work, particularly for a European used to a particular climate and situation.  No, rainforest is not glamorous.  But it has a glamor, in the old English sense of casting a spell over those it has charmed into visiting its depths and trying to know its ways.  The visitor to tropical rainforest who appreciates its biological richness and functioning is always charmed, and returning to it feels like a return to something very special indeed.

Although I have conducted field work in tropical rainforests in Africa, Australia and other parts of South America, one reason why I have long wished to visit the Atlantic Rainforests of Brazil is that John Tweedie, whose life and career I am researching,  wrote frequently in his letters to William Hooker about his love of the forest in South Brazil.  And the forest has not disappointed me: it is beautiful and wonderful, even if wet and, because of its altitude of around 1000 metres a.s.l., quite cold.

One of the most spectacular aspects of the Atlantic Rainforest is the sheer abundance and diversity of epiphytic plants, a sub-type of rainforest communities that can only be supported in areas of high rainfall such as this.   Over the last couple of days, Andre, Coquinho, Vini and I have hiked a couple of forest trails despite the rain, and orchids and ferns, bromeliads and forest cacti were more abundant than I’ve ever previously seen.  These plants are generally thick and complex in form, as they store water internally in leaves and stems, or within tanks formed of overlapping leaf bases.  On one short section of trunk, up to waist height, we counted six different orchid species mixed together, and saw at least 20 species along a 3km trail on Sunday.  Coquinho has been putting together a checklist of the orchids around the field station and it currently numbers 130 species.  Astounding diversity!

As we walked and slid and macheted our way through a 9km trail on Sunday, the ringing calls of male Bare-throated bellbirds (Procnias nudicollis) were resounding through the forest, whilst smaller birds played hide and seek from our binoculars.  Still scoring plants for wind and animal pollination, as I previously described, we recorded 75 plant species in flower along the trail, but most of them we encountered only once or twice.  Diversity and rarity go together in these plant communities.  No wonder Tweedie loved the Atlantic Rainforest; there is always something new to collect and the climate under the trees is cooler than in the open pampas grasslands of Argentina, where he was based.  Perhaps the rain made him think of his home in Scotland?  It’s called rainforest for a reason, right?

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Scientists Must Write (and Speak and Listen and Review and Edit)

“Scientists Must Write” was the title of a book published back in the late 1970s by a former tutor of mine, Robert Barrass, at what was then Sunderland Polytechnic (now the University of Sunderland).  I had assumed the book was now a long gone publishing memory and no longer available.  But it turns out that Robert updated it in the early 2000s and it’s still in print.  Almost 30 years (30!) later I can clearly remember Robert impressing upon us the importance of good writing skills for scientists-in-training.  At the time I was as far from being a professional scientist as it’s possible to be and so didn’t fully grasp this, but nonetheless what he said chimed with my own notions that writing was important, even for a scientist.

Nowadays I realise that it’s not just the writing of standard, academic papers, book chapters and books which  is essential: writing of all kinds is a necessary facet of the life of a research active scientist.   This June sees the publication of two contrasting articles that illustrate this point.  The Royal Horticultural Society’s journal The Plantsman has published a piece entitled “The Importance of Native Pollinators“, whilst the historical journal Notes and Records of the Royal Society has published my paper on “John Tweedie and Charles Darwin in Buenos Aires“.  Neither of these is standard academic fare, at least for me.  The first is a popular article aimed largely at gardeners and others interested in understanding more about pollinator conservation.  The second, whilst academic and rigourously peer reviewed, is primarily historical rather than scientific.

Why am I writing popular conservation articles and historical papers?  Largely for different reasons, though they are linked by my overall fascination with biodiversity.  The Plantsman article is an example of taking ideas and findings from the LBRG‘s research and presenting it to a wider audience who might, at the least, find it interesting and hopefully useful.  One might describe it as “popular science” though I don’t really like the term: it suggests that it’s somehow different to “real” science, which is not the case: it’s really only the format of the presentation which is different.

The John Tweedie/Charles Darwin paper reflects my desire to understand where our scientific knowledge of biodiversity comes from.  As scientists and conservationists, we draw conclusions about species’ distributions, conservation threats, extinctions, and so forth, based on information from specimens that have been collected by people like Tweedie and Darwin, and curated at places such as Kew and the Natural History Museum.  By its nature it’s a historical process and historical research helps us to understand how we arrived at our current understanding.  The only reason we know that 23 species of bee have gone extinct in England since about 1800 for example, as I cite in my Plantsman article, is that over the past two centuries specimens and observations have been recorded and analysed.  This is an ongoing process, exemplified by the BWARS project mapping the spread of Bombus hypnorum   the most recent addition to the UK’s native bee list.

As well as writing we scientists gain much from listening to what others in our field have to say and a well attended, and very interesting, meeting in London last week launched the British Ecological Society’s Macroecology Special Interest Group .  The range of talks spanned community structure, interaction networks, ecosystem services, latitudinal gradients and disease biology, all at the large spatial and temporal macroecological scales covered by this subdiscipline of ecology.  Or is it really a multidisciplinary field, a merging of old fashioned biogeography with more modern ecological approaches?  Who knows, perhaps this is sterile semantics; as I mentioned to one of the organisers in the pub afterwards, “macroecology” seems to me to be more about a philosophy of approach rather than a field in itself.

Formal teaching has largely finished for the time being, so in addition to research activities and university administrative work, much of the remainder of the last couple of weeks seems to have been taken up with editorial and peer reviewing duties for journals, including PLoS ONE, for which I’m an academic editor. This can be time consuming and thankless, but is absolutely vital if the whole system of scientific publishing is not to grind to a halt.  Scientists must write, but that writing is supported by a body of individuals who act as peer reviewers, editors, proof readers, and so forth.  Collectively that eats up a lot of scientist-hours and is something we should never take for granted.