Cave-dwelling plants in SE Asia

cave 7-2
One of the many hundreds, if not thousands of caves located in the limestone karst of SW China. It is within such caves that we are discovering many new species of plants, very often from the nettle family.

Since 2007 I have been working with colleagues at the Chinese Academy of Sciences Guilin Institute of Botany on documenting the unusual cave flora of SW China and Guangxi. My interest stems from the fact that one of the most common groups of plants in these caves are two particular groups of nettles, members of the succulent herbaceous genera Elatostema and Pilea. It is also heavily influenced by the presence of a very knowledgeable and dedicated botanist at the Guilin Institute of Botany, Professor Wei Yi-Gang.

Cave dwelling Elatostema QMC
Examples of some of the strange looking flower clusters in the nettle genus Elatostema, the most common group of nettles to be found growing in caves

More recently I have wanted to see whether it is possible to explain how, and when these plants occupied these ancient caves. Possible explanations are that they evolved in the caves, some of which are 15-25 million years old; alternatively that they represent plants which grew outside of the caves when the climate was different, during the last ice-age for example; lastly that they are relics of plants which grew in the forest understory outside of the caves prior to the arrival of agriculture in the area maybe 1,500 years ago. To try and answer these questions I have, together with a Masters student Alfred Gay, used DNA extracted from the leaves of the plants to look for patterns which may point to one of the three possible explanations above. Click here to see a slide show of the preliminary results.

A carpet of nettles growing in the back of one of the caves that we surveyed in SouthWest China, taken with a tripod!

Another interesting line of research would be how these nettles survive in such low light levels. In some cases 1/50th of 1% daylight! For the moment though I am focussing on documenting their diversity and describing the new species we find but in the long-term I am hoping to find collaborators to explore these other areas of research.


Hidden treasures of the Museum backlog collections

Lichen encrusted boot collected in Ecuador by a Cambridge University Expedition in 1967. The boot was finally accessioned in 2011 and included a new lichen record for Ecuador at the time

All large Museums and herbaria have backlogs of specimens that are waiting to be processed and incorporated into the collections, sometimes for a century or more. Whilst to many institutions, specimen backlogs can seem like an eternal cloud pulling at their consciences, the reality is that they are an inevitable consequence of uneven collecting effort, bequests, absent-minded scientists and the amount of money available to maintain natural history collections. It might be better to think of these collections in limbo as potential treasure troves for those who finally do get the time and resources to process them. Last week I went to meet Natural History Museum (NHM) curator Holger Thüs, herbarium technician John Hunnex and their volunteer team in the backlog processing area of the Botanical Collections.

One of several boxes full of packets collected by a lichenologist called West in the early 1900s. These collections contain many records from all over the UK and are important as they help us see how lichen distributions have changed over the past Century

Thanks to the efforts of Holger and his team at the NHM, over 2,300 boxes of lichen backlog have been processed in the last three years. During their efforts some important and hitherto unknown historical collections have been recovered which include specimens collected by Charles Darwin from Tierra del Fuego, David Nelson collections from Captain Cook’s third voyage and Francis Masson collections from South Africa, as well as many others. Maybe less glamorous though, but of great scientific value however are the big collections of 19th and early 20thC lichens from the UK as these provide an important snap shots that help document the impact of industrialisation on air quality and the landscape as it began and later as it gained momentum. These collections plug gaps in our knowledge thereby making the UK biota one of the most completely known.

Long dispersed between a cupboard in the herbarium and storage areas in the museum towers, this collection of lichens compiled by William Mudd in the middle of the 19thC contains specimens which formed the basis of the first UK lichen flora published in 1861 and material which he received in from colleagues across Europe. It was identified as such by lichen curator Holger Thues and visiting scientist Mark Seaward

Of particular value was the discovery of what is likely William Mudd’s personal lichen collection from the middle of the 18thC and which contains specimens which formed the basis of the first UK lichen flora published in 1861, ‘A manual of British Lichens‘. The 52 book-like fascicles of unbound sheets and hundreds of specimens were  rediscovered dispersed between cupboards in the Cryptogammic Herbarium and in stores at the top of the Museum’s towers where they were thought to represent spare / duplicate material for distribution. The fact that such a treasure was found in the backlog hints at what other amazing collections could be found in the coming years as the work to process it continues.

The William Mudd collections as they are housed now. The volumes are now  stored in a climate-controlled and pest-free space within the Bernard Sunley suite at the Natural History Museum