Herbarium: scrap books of potential medicines

Emory University ethnobotanist, herbarium curator and intrepid explorer, Cassandra Quave tells describes her precious records...

Chris - I'm intrigued by your role as someone who runs a herbarium because there was a great story a few years back where scientists worked out from stored specimens, what caused the Irish potato famine. That was done in the Southeast of the UK. They happened to have a specimen and they could work out what caused something that happened historically over 150 years ago. Are you able to delve into what you've got in herbaria to find treatments, or are you having to actually get out there in the wild and look at the real deal?

Cassandra - That's a great question. First let me just explain what a herbarium is because I think sometimes people envision this lush tropical greenhouse, and in fact, a herbarium is a museum of dead plants that are pressed to paper. I always tell my friends, I have a brown thumb. I'm very good at finding and killing plants and drawing them and gluing them to paper, but herbaria are incredibly important as records of life at specific points in time in specific places. Your mention of the Irish potato famine, those specimens are a record of what the crops looked like, what other microbes may have been on the leaves at that time. We now have more advanced chemistry tools, we can look into the chemistry of fragments of those specimens. In reality, when it comes to drug discovery of looking for new molecules we generally need a lot more material than what you would find just on a press specimen. We're talking about 40 grams of dried leaves to really kick start the search process. Those herbarium specimens are incredibly important for authenticating and really having a documented record of which plants we're working on. This is a big issue in the literature because there are lots of publications on plants, including clinical studies on botanical remedies and some of the reasons we get into trouble with seeing different outcomes is often these studies don't really have rigorous authentication of their materials, and the chemistry even of related species can be quite different. The chemistry of the same species can be different also depending on where it's grown because of the influence of environmental factors. Really controlling for records of what species you're working on and also controlling or characterising the chemistry is really important to that process.

Chris - Going back to something we were talking about earlier with climate change causing loss of plant species, we've also got the technological revolution causing loss of some cultural values. People are increasingly moving to cities and they're abandoning their relationship with nature. Is there anyone out there, or are there projects out there to try and capture that vast local knowledge before it is lost to the technological revolution so that we've got those folklore remedies stored somewhere so that people like you can subsequently follow them up and hopefully find the next blockbuster drug in the future?

Cassandra - I mean, absolutely. That's really the bread and butter of what ethnobotanists do in the field, it's recording traditional knowledge, and sometimes we also call it traditional ecological knowledge, to really document the ways that people use plants in different cultures. We've done a lot of work in the Balkans and had a really nice study a number of years ago where we looked at two different cultures that had two different languages spoken, different practices. We really examined how those cultural lenses influenced the way that they interacted and engaged with plants in the same environment. They're in the same mountain range, relatively close to one another, but don't intermarry. There were huge differences in not only how they named plants in these different languages, but also which plants were used for food and medicine, even in places where you have the same species growing, the historical trajectory, that cultural lens is incredibly important. We're in a race to save that knowledge before it's lost forever. I think about this in the Amazon as well. We have around 400 different distinct tribal groups and each tribal group has its own language way of viewing and understanding the world and different systems of medicine. When those knowledge keepers pass on without sharing that information with apprentices, where there's a break in the oral tradition of teaching the next generation how to use nature as medicine, we're really losing the equivalency of libraries of knowledge. There is an urgent need to record this knowledge and also document and authenticate the plants, as we mentioned before in herbaria, before we run out of time.