Plant Cuttings

Plants and Pinatubo, Prestahnukur, Popocatépetl…

Plants are generally sessile organisms that, unlike their puny animal ‘cousins’, can’t get up and run away if the environment is not to their liking. Botanicals by-and-large put up and shut up. Accordingly, that fundamental fact of their existence has led them to adapt to a remarkable array of abiotic factors, e.g. temperature, drought, high light levels, low light levels, excess UV, salinity, fire, heavy metals, herbivory, etc. Yet, however long and imaginative that list may be, what are the chances that you would have included volcanoes (ruptures on the Earth’s crust “that allow hot lava, volcanic ash, and gases to escape from a magma chamber below the surface”)?

Image MesserWoland/Wikipedia.

Pretty low, I imagine. Yet, these are a natural hazard and some plants appear – not so surprisingly – to have adaptations that have been driven by this most incendiary of geological phenomena. At least that is the suggestion from study of the epidermis of cycads by Maria Rosaria et al.

Using a range of light, fluorescence and electron microscope techniques they investigated micromorphological features of the cuticles of 12 of the 14 recognised extant species in the genus Dioon, which taxa are native to present-day Mexico and central America. Structural similarities between stomata in modern-day Dioon and extinct Dioon-like Pseudoctenis ornata (from c. 115 millions of years ago) lead to the notion that volcanism may have led to the development of this particular feature. Why?

P. ornata grew at a time and in a habitat where volcanic events and related phenomena were commonplace, and previous work by Ana Archangelska et al. has suggested that its cuticular features may indicate adaptations to volcanic stress. Developing that idea, Rosaria et al. propose that the structure of the Dioon stomatal complex could represent a response to the high level of volcanic activity in the genus’ evolutionary past in the Mesozoic, allowing the plant to avoid the occlusion of stomatal pores by volcanic ash and the penetration of toxic gases, and to survive those particular environmental conditions. An intriguing case of palaeoforensic botany if ever there was, but giving insights into some of the environmental conditions plants have had to withstand during their terrestrial tenure.

Maria Rosaria Barone Lumaga, Mario Coiro, Elisabeth Truernit, Boglárka Erdei, Paolo De Luca, 2015, ‘Epidermal micromorphology in Dioon : did volcanism constrain Dioon evolution?’, Botanical Journal of the Linnean Society, vol. 179, no. 2, pp. 236-254

[Ed. – for those looking for experimental studies into the effects of modern-day volcanism on plant cuticles, I’ve tracked down a PhD thesis by Bartiromo Antonello from 2011 to whet your appetite [available to download at]

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