One of the things I was keen to work on after getting back from the Ethnobiology course at Kew Gardens, was to make sure any toxic plants in the Manchester Museum herbarium had proper procedures for handling and research.
While there are many plants in herbaria that could be considered mildly toxic, it was the ones that might present an immediate hazard to staff and visitors that I was most concerned with. Dangerous specimens/substances in Botanical collections include:
The Rosary Pea (Abrus precatorious)
Curare (Strycnhos toxiferia)
Strychinine (Strychnos nux-vomica)
There are other plants I’m working on at the moment, but these are the main concerns. The first thing I did was systematically go over a list of potentially hazardous plants and looked for their locations on our collections management system. I started with Abrus precatorious, or the Rosary Pea, and found several boxes and herbarium sheets containing the seeds.
The Rosary pea is very asthetically pleasing, and for this reason it is made into jewellry by various cultures. Unfortunately a lot of jewellrey makers have died by pricking their fingers during this process. Yup, the rosary pea is probably the world’s most toxic seed. While intact, the seeds are mostly harmless (if I can use that word), but once the outer coating is scratched or the seed is crushed, as little as 0.1–1 µg/kg can kill a human. Abrus precatorious causes total bodily system shut down. For this reason, the collection needed warning labels and safety sheets on how to handle these specimens! I’ve since labelled them with easy to see toxic warning stickers and have written a safety data sheet on how to handle them (never without gloves and avoid touching your face!)
The second problem was herbarium sheets. Some of the sheets contained seeds that were still sitting in their original pods. I was worried that they might become loose, roll around and potentially be crushed when handled, so I wrapped the species folder in tissue paper to prevent anything falling out. All sheets, boxes and folders were also labelled with toxic warning stickers.
I also labelled Strychnos nux-vomica and Strychnos toxifera this way. The latter plant is a source of Curare, a poison used by Amazonian tribes to tip arrowheads.
You may wonder why we have such dangerous specimens in our collections. The reason is they are a valuable resource for scientific study. For example, Curare has been shown to have anesthetic properties when tested in the lab. Abrus precatorious is currently being used in anticancer studies. Who knows what else we might discover? Just treat these plants with a healthy dose of respect and always follow health and safety rules!
For more about health and safety with regards to these plants, please read this fabulous paper: Oh, no! Ethnobotany! (PDF file)