Being an avid supporter of the importance of plants (I do hope that’s come over quite strongly in my various blog items..?), I’m always keen to share with my students [well, any- and everybody really…] how many plant species there are. For several years the best – i.e. biggest! – number I’d found was 352,000 species of flowering plants. Although officially an estimate, it’s quite impressive. However, the most up-to-date tally is 369,400 angiosperm species (RBG Kew (2016) The State of the World’s Plants Report – 2016).* But, and regardless of how many there are** , why should we be interested in all – or indeed any – plants anyway?
Well, directly (e.g. as food for humans) or indirectly (as food for the animals whose flesh and/or other products we humans eat), plants are essential to keeping people alive. But they contribute so much more than that. That same Kew Report states that 31,128*** plant species currently have documented uses, over half (19,192) of which are used ‘socially’ or medicinally, more than a third have a materials use, and 9,187 are exploited as food for humans and other animals.**** All of that’s on the positive side for plants.
On the negative side, 21 % of global plant species are currently threatened with extinction according to IUCN Red list criteria, i.e. are in the Vulnerable, Endangered, or Critically Endangered categories. And – maybe surprisingly? – almost a third of that risk is because of conversion of land for agriculture. Which basically means that, if we are to have any chance of studying the plant diversity that exists (or is estimated so to do), we need to work to conserve the habitats wherein plants live, i.e. look after this planet a whole lot better than we’re doing at present! Now there’s a novel notion.
There’s a lot more in the Kew Report than those items I’ve cherry-picked above (but best to do so whilst there are still cherries left to pick…), so do download your own copy – it’s free – and find your own reasons to be cheerful, or scare yourself to sleep with its somewhat depressing statistics.
*Or 390,900 vascular plants (which includes angiosperms, gymnosperms, ferns and fern-allies, but excludes the bryophytes amongst the Kingdom Plantae). However, if that’s too many species and too much information, remember that, according to Dr Markus Eichhorn, forest ecologist at The University of Nottingham (UK), all of this bewildering phytobiodiversity can be reduced to only four kinds of plants: Plants you can eat, Plants you can kill people with, Plants you can use to get high, and The rest.
**And don’t forget, that this is still many fewer than the 386,500 species of beetles on the planet (Slipinski et al.)! Now, it may be the case that ‘the Creator has an inordinate fondness for these insects’ (a quote attributed to JBS Haldane – British geneticist, biochemist, professor and writer) over plants because of the multilegged animals’ numerical taxonomic superiority. However, might it not be the case that God, in her infinite wisdom, actually created many more plant species than beetles but chose to hide them in places so that we might not discover all of those extremely useful organisms until we had learnt to look after them..? If that’s the case, apparently the most likely hiding places are Brazil, Australia, and China. However, if there are really 450,000 flowering plant species – as Stuart Pimm and Lucas Joppa suggest – it’s Plants 1: Beetles 0… [Ed. – all of this numerical nonsense is trumped by the estimated 1 trillion (i.e. 1012) species of microbes on the planet anyway. So, all bets are now off!]
***Interestingly, if you add up the number of species in each of the 10 categories that are listed, you get a total of 59,029, which gives an indication of how many plants have multiple uses. Somewhat irritatingly, though, I couldn’t find a list – or reference to a source that contains the list – of all of those (or indeed any of them by name!) species and what they are used for…
****I.e. plants keep us healthy and cheerful, clothed, and fed. Which trio of testamentary tracheophyte truths is reminiscent of the three words ‘Miserable’, ‘Naked’, and ‘Hungry’ that Prof. Armstrong displays on the ‘board’ to start his classes in economic botany, and which is what us humans would be without plants.
Neil A. Brummitt, Steven P. Bachman, Janine Griffiths-Lee, Maiko Lutz, Justin F. Moat, Aljos Farjon, John S. Donaldson, Craig Hilton-Taylor, Thomas R. Meagher, Sara Albuquerque, Elina Aletrari, A. Kei Andrews, Guy Atchison, Elisabeth Baloch, Barbara Barlozzini, Alice Brunazzi, Julia Carretero, Marco Celesti, Helen Chadburn, Eduardo Cianfoni, Chris Cockel, Vanessa Coldwell, Benedetta Concetti, Sara Contu, Vicki Crook, Philippa Dyson, Lauren Gardiner, Nadia Ghanim, Hannah Greene, Alice Groom, Ruth Harker, Della Hopkins, Sonia Khela, Poppy Lakeman-Fraser, Heather Lindon, Helen Lockwood, Christine Loftus, Debora Lombrici, Lucia Lopez-Poveda, James Lyon, Patricia Malcolm-Tompkins, Kirsty McGregor, Laura Moreno, Linda Murray, Keara Nazar, Emily Power, Mireya Quiton Tuijtelaars, Ruth Salter, Robert Segrott, Hannah Thacker, Leighton J. Thomas, Sarah Tingvoll, Gemma Watkinson, Katerina Wojtaszekova, Eimear M. Nic Lughadha, 2015, 'Green Plants in the Red: A Baseline Global Assessment for the IUCN Sampled Red List Index for Plants', PLOS ONE, vol. 10, no. 8, p. e0135152 http://dx.doi.org/10.1371/journal.pone.0135152
Stuart L. Pimm, Lucas N. Joppa, 2015, 'How Many Plant Species are There, Where are They, and at What Rate are They Going Extinct?', Annals of the Missouri Botanical Garden, vol. 100, no. 3, pp. 170-176 http://dx.doi.org/10.3417/2012018
Kenneth J. Locey, Jay T. Lennon, 2016, 'Scaling laws predict global microbial diversity', Proceedings of the National Academy of Sciences, vol. 113, no. 21, pp. 5970-5975 http://dx.doi.org/10.1073/pnas.1521291113