Readers may be familiar with the weekly count-down to the 400th anniversary of botanical research and teaching at the University of Oxford (UK) on 25th July 2021. Four centuries of plant science is impressive and deserving of celebration.* But, they’ve got their dates wrong as the roots – quite literally – of plant sciences at the University of Oxford go back over 320 million years.
This nugget of purest phytochronological gold was unearthed by Alexander (Sandy) Hetherington, a post-graduate student in Oxford University’s Plant Sciences Department. Pursuing his research on rooting systems of ancient trees, and examining microscope slides of fossilised soils held at the University Herbaria, he noticed a structure that was similar to that within the root tips of modern-day plants.** What he had chanced upon was the first sighting of root meristem cells of a long-extinct plant from coal-balls of the Carboniferous period, approx. 320 millions of years old.
Named Radix carbonica *** Hetherington, Dubrovsky et Dolan sp. nov., the data presented for this plant indicate that this is the first – and so far only – example of a root fossilized during active growth, which has preserved the cellular organization of the meristem. Interestingly, although similar to modern-day roots, the structures identified indicate a previously unknown and unique pattern of cell division that gives important insights into the control of root formation in extinct plants.
Whilst this discovery is clearly of value in contributing to our understanding of plant design, evolution and development, maybe there is an even more important lesson here. It has been remarked before that herbaria and similar collections of naturabilia [‘natural history memorabilia’…] are treasure troves of as-yet-undiscovered biological jewels, yet their very existence is often questioned and even threatened by the unenlightened in society. Underlining the continued relevance and value of herbaria, and as stated by Liam Dolan (Sherardian Professor of Botany at Oxford, and Hetherington’s supervisor), this discovery “also shows the importance of collections such as the Oxford University Herbaria – they are so valuable, and we need to maintain them for future generations.” Hear-hear!
* And the weekly plant profiles produced are themselves ideal for teaching aspects of plant science, thereby perpetuating at least one half of that noble botanical tradition.
** Even though Hetherington actively sought root tips in the material he examined, it still takes a trained eye to spot such microscopic features and recognise their importance, and the famous maxim attributed to Louis Pasteur, that chance favours a prepared mind, seems apt.
*** Intriguingly, the taxonomic position of the plant – known so far only from its root tip – remains elusive as indicated by the ‘systematic palaeobotany’ in the article’s Supplementary Discussion. Whilst R. carbonica is confidently assigned to the Subdivision Tracheophyta (‘vascular plants’), its Class, Order and Family are all ‘incertae sedis’, a lovely Latin phrase which loosely translates as ‘we have no idea’.
[Ed. – For those who wish to take ancient tree root stories further, we recommend “Networks of highly branched stigmarian rootlets developed on the first giant trees” by Hetherington et al.]
Alexander J. Hetherington, Joseph G. Dubrovsky, Liam Dolan, 2016, 'Unique Cellular Organization in the Oldest Root Meristem', Current Biology, vol. 26, no. 12, pp. 1629-1633 http://dx.doi.org/10.1016/j.cub.2016.04.072
Boer Deng, 2015, 'Plant collections left in the cold by cuts', Nature, vol. 523, no. 7558, pp. 16-16 http://dx.doi.org/10.1038/523016a
M. Greve, A.M. Lykke, C.W. Fagg, R.E. Gereau, G.P. Lewis, R. Marchant, A.R. Marshall, J. Ndayishimiye, J. Bogaert, J.-C. Svenning, 2016, 'Realising the potential of herbarium records for conservation biology', South African Journal of Botany, vol. 105, pp. 317-323 http://dx.doi.org/10.1016/j.sajb.2016.03.017
Alexander J. Hetherington, Christopher M. Berry, Liam Dolan, 2016, 'Networks of highly branched stigmarian rootlets developed on the first giant trees', Proceedings of the National Academy of Sciences, vol. 113, no. 24, pp. 6695-6700 http://dx.doi.org/10.1073/pnas.1514427113