Category Archives: Africa

Edible Apocynaceae: a new global synthesis of diversity, conservation and pollination just published – and a personal landmark for me!

This year – 2026 – marks the 40th anniversary of my first publication. Forty years. Imagine that – I certainly can’t! It feels like a long time ago, a distant memory, another life. I was 21 and I hadn’t even begun my undergraduate degree. After a less-than-successful time at school I decided to complete a Higher National Diploma (HND) qualification in Applied Biology at Sunderland Polytechnic (now the University of Sunderland) that I hoped would get me a place on a degree course. As it turned out, it did, but during my HND I completed a research project which (with the encouragement of my then supervisor, the late cactus expert Geoff Swales*), was subsequently published in December 1986 as “Adaptation to arid environments in the Asclepiadaceae” in the British Cactus and Succulent Journal.

That was the modest start of a botanical love affair with asclepiads (now subsumed into the family Apocynaceae) that has persisted to this day and resulted in over 20 research papers, chapters, and more general articles, plus appearances in both of my books.

The latest of these papers is published today and, as well as being a 40 year milestone for me, it’s a paper that I am inordinately proud of, as it represents an amazing coalescence of ethnobotany, taxonomy, conservation, biogeography, cultural science, and pollination ecology. And I managed to sneak in a citation of the 1986 paper that started the whole thing!

This paper is the first global review of the diversity of edible species in a family that is usually considered to be highly toxic and produces a lot of sticky latex to deter herbivores. Yet that reputation turns out to be only part of the story. Our survey found no fewer than 440 edible species of Apocynaceae worldwide, which works out at about 7.7% of the family (and is definitely an under-estimate). They occur across all of the major evolutionary lineages of the family, and in most of the main biogeographic regions where these plants grow.

What people eat is also far more varied than you might expect. Fruits are the commonest edible part, but roots and tubers are also important, and in different places people consume leaves, stems, flowers, nectar, latex, bark and even wood ash used as a condiment. That diversity is not random: our analyses show clear phylogenetic and geographic patterning in which parts are eaten. In other words, both evolutionary history and regional cultural practices help to shape how Apocynaceae are used as food.

One especially interesting result is that edible Apocynaceae appear, on current evidence, to be less threatened than non-edible members of the family. But that comes with a big health warning: more than 80% of species, edible or otherwise, have never been properly assessed for conservation status. So there is still a huge amount that we do not know.

The same is true for pollination. Many of these plants depend on animal pollinators to produce the fruits and seeds that people eat, yet pollination data are missing for most edible species, including about 90% of those whose edible parts are directly pollinator-dependent.

For me, that is one of the most striking messages of the paper. Hidden inside a family best known for poisons and medicinal compounds is a substantial, globally distributed food resource, much of it tied to local knowledge and wild harvesting. It is a reminder that botanical and cultural diversity, conservation, and pollination ecology are all bound up together. And, as a nice bonus, the study even uncovered an unexpected taxonomic surprise in China, where one edible species turned out to belong in an entirely new genus, Kushengia. The edible flowers of Kushengia sinensis are shown in the image at the top of this post – lightly boiled, stir fried with garlic, and thoroughly delicious!

Here’s the reference with a link to the paper, which is unfortunately pay-walled. If anyone wants a copy, send me a request via my Contact page:

Ollerton, J., Albuquerque-Lima, S., Liede-Schumann, S., Galetto, L., Endress, M.E., Forster, P.I., Torres, C., Fishbein, M. & Ren, Z.X. (2026) Edible Apocynaceae: phylogeny, biogeography, conservation and pollination insights from a global synthesis. Taxon 75: e70131

*It goes without saying that I’m incredibly grateful to Geoff and the other teachers and supervisors who, during the course of my education, encouraged me in my studies. During one lab session with Geoff we were each given a cactus seed and asked to study it under a microscope and draw it. Afterwards I pocketed the seed, took it home, and germinated it. That cactus – a specimen of Parodia (Notocactus) mammulosus – is still growing on my windowsill, a living reminder of a great mentor.

Pollination as a matter of national security

In these turbulent times it’s hard to know where to focus one’s gaze. Do we concentrate on Ukraine? Greenland? Venezuela? Sudan? China? Russia? The Middle East? The rise of the far right and religious fundamentalism? Cyber security? Global organised crime? If it’s confusing and worrying for the average person, imagine what it’s like for national security services who are charged with assessing and responding to such threats.

It is increasingly recognised that national security in the 21st century extends beyond military threats to encompass food systems, economic resilience, public health, and the stability of critical ecological infrastructure. Which is why it’s no surprise to learn that the UK’s national security organisations – MI5 and MI6 – have just released a report titled Global biodiversity loss, ecosystem collapse and national security: A national security assessment.

The report has been covered by The Guardian under the heading “Biodiversity collapse threatens UK security, intelligence chiefs warn” and the article begins:

The global attack on nature is threatening the UK’s national security, government intelligence chiefs have warned, as the increasingly likely collapse of vitally important natural systems would bring mass migration, food shortages and price rises, and global disorder.

This framing explicitly treats biodiversity loss not as an environmental side issue, but as a systemic risk multiplier capable of amplifying existing geopolitical, economic, and social stresses. I have emboldened two words in that quote in order to emphasise that this report is very much about the state of the world, not just the state of my home country. In an interconnected global food and trade system, ecological collapse in one region rapidly propagates elsewhere through markets, migration, and political instability. What happens globally has implications locally; not just food security from imports, but “geopolitical instability, economic insecurity, conflict, migration and increased inter-state competition for resources”, to quote the report.

Where does pollination fit into this? As far as I know, pollination has never been singled out in security analyses, yet it underpins many of the very food systems, rural economies, and ecosystem functions upon which national resilience depends. In my book Pollinators & Pollination: Nature and Society I mention “food security” about ten times, as I firmly believe that loss of pollinators is a serious issue to food supply chains. The report similarly states that:

UK food production is vulnerable to ecosystem degradation and collapse. Biodiversity loss, alongside climate change, is amongst the biggest medium to long term threat to domestic food production – through depleted soils, loss of pollinators, drought and flood conditions.

But I would go further and state that loss of pollination by insects and vertebrates poses a national security threat that extends far beyond just their role in food production.

Let me explain why I believe this.

The Global biodiversity loss report focuses on six different parts of the world (and seven ecosystems) that it considers “critical ecosystems…at risk of collapsing”. One of those areas – the coral reefs of Southeast Asia – is not directly dependent upon pollinators to support its long-term functioning. Two areas – the boreal forests of Canada and Russia – are dominated mainly (though not exclusively) by wind-pollinated trees, such as conifers and birches. The other four ecosystems, however, have a dependence on pollinators that ranges from significant to enormous. These are the Mangroves of Southeast Asia and the Himalayas (both significant) and the Amazon Rainforest and Congo Basin (both enormous).

What do I mean here by words like “significant” and “enormous”? What is my measure? What I mean is the number and proportion of flowering plants—particularly dominant species, often trees—that underpin most ecosystem functions, such as photosynthesis and carbon storage, and that rely to some extent on pollinators to reproduce.

In high elevation areas such as the Himalayas, I know from experience that it’s common for there to be a mixture of wind and animal pollinated species in communities. Similarly, mangrove species include some which are wind pollinated – see this review for example. In other words, the long-term population stability of Himalayan woodland and Southeast Asian mangrove forests is, in large part, dependent on the pollinators that those ecosystems support. If those pollinators were lost, in the long term (decades to centuries) wind-pollinated trees would dominate and biodiversity would significantly decline.

The situation in the forests of tropical South America and west Africa is rather different. Not only is there a much greater diversity of plant species in these ecosystems, but in these largely rainforest regions, often all of them are animal pollinated, as we showed in this paper and which is reflected in the graph above, which comes from my book. Lose the pollinators and we lose the long-term viability of ecosystems that provide regionally- and globally-vital functions.

Ultimately, if we are to protect pollinator communities, and the ecosystem functions and services they provide, we need to take their conservation more seriously than we do at the moment. Framed this way, pollinator conservation becomes a form of preventive security investment, analogous to maintaining flood defences or safeguarding energy and cyber infrastructure. The European Union’s Pollinator Initiative and the projects that it supports, including Butterfly and ProPollSoil in which I’m involved, is a good example. Likewise, there are policy movements appearing in China, as I recently reported. But biodiversity conservation is a global issue, as the security services report makes clear, and that applies to pollinators.

There will no doubt be sceptics out there who think that I am over-playing the importance of pollinators and pollination. That’s fine, it’s good to have these debates. Pollination is not a national security issue in the narrow, traditional sense of defence against hostile actors. But in the 21st-century security landscape, where threats are systemic, slow-burning, and ecologically grounded, pollination loss clearly qualifies as a strategic risk to national stability and resilience.

In that respect, I believe that the question is not whether pollination is a national security issue—but whether national security thinking has yet fully adapted to the biological foundations on which societies depend.

Aggressive dominance of acacia floral resources by wild East African lowland honey bees – a new study just published

Back in August 2022, Karin and I traveled to Kenya where I was teaching on a Tropical Biology Association field course at the Mpala Research Centre – see my posts from the time here and here.

Students on the course have to complete an extended group project, with supervision by teaching staff. Two of the groups looked at the visitors to flower heads of one of the dominant savannah acacias and the interactions between wild honey bees of the native subspecies and the other insects. There have been rather few studies of this honey bee in the wild and so we wrote up the work as a short research note that has now been published in the African Journal of Ecology.

The photo above shows the authors – ‘Team Etbaica’ – from left to right: Luis Pfeifer, Swithin Kashulwe, me, Caka Karlsson, and Janeth Mngulwi.

Here’s the reference with a link to the publisher’s site – the paper is open access:

Kashulwe, S., Mngulwi, J. B., Karlsson, C., Pfeifer, L., & Ollerton, J. (2024) Aggressive dominance of acacia floral resources by wild east African lowland honey
bees. African Journal of Ecology 62, e13271. https://doi.
org/10.1111/aje.13271.

Here’s the abstract:

The East African lowland honey bee (Apis mellifera scutellata) is reported as an aggressive subspecies of the Western honey bee, but few studies have investigated the impact of its aggressiveness on other insect pollinators. Observations of flower visitors to Vachellia (Acacia) etbaica and interactions between honey bees and other insects were conducted in 2022 in Mpala, Kenya. A total of 873 individual flower visitors were recorded, the most frequent being Hymenoptera, followed by Diptera and Lepidoptera. Honey bees dominated floral resources in the morning and late afternoon. When honey bees encountered other types of insects, they displaced the latter from flowers 100% of the time. This has never been observed in other Western honey bee subspecies, and we recommend further research on these taxa.