Green miner: new plant species mines metal
A plant that takes metal from the ground all by itself: a natural way to mine or to clean the soil. PhD student Roderick Bouman (Hortus Botanicus Leiden) described a new plant species from Sabah, Borneo, which can be used to extract nickel. In an open access article in Botanical studies, he and the other authors present the new species: Phyllanthus rufuschaneyi.
‘The species was found in the wild already in 2013 and planted in a small garden near a reserve,’ says Bouman. Here the plant attracted attention because of its excellent ability to absorb nickel from the soil. For this reason the plant was involved in research on agromining: the extraction of metal from the soil with the aid of plants. ‘There are several possible applications’, Bouman explains, ‘for example extracting metals from areas where they occur naturally in high concentrations. It can also be used for cleaning old mining areas that are now polluted with metals. The plants are planted and harvested after a while, so that the metals are also taken out of the ground.’
A new species
Researcher Antony van der Ent (University of Queensland) had been working with the plant for a while and suspected he was dealing with a new species. Because the plant achieved such good result as metal extractor, it was important for him to provide the plant with a proper identification. That is why he called in the help of Bouman and his supervisor Peter van Welzen. ‘We compared the specimens of Van der Ent with species that we already know from Borneo. Because it did not match anything, we decided to describe it as a new species,’ says Bouman.
A large group
The plant belongs to the genus Phyllanthus, a diverse genus of nearly 900 species. The different species are mainly distinguished on the basis of the flowers. ‘What makes this genus so fun to work with, is its diversity. Many researchers find the species difficult to identify, because the flowers are often very small and there are just many different species. With my research we try to better understand the structure of the group and also look at its distribution history and metabolites.’
Van Welzen worked on the taxonomic description, Van der Ent performed the metal analyses and Bouman determined where to place the plant in the taxonomic classification. It stood out that the flowers had many properties of several other Phyllanthus species. That made it difficult to place the species in a certain group. The group where the plant was ultimately placed has been chosen based on the nectar winches. DNA research still has to confirm whether this placement is correct.
The researchers decided to name the plant Phyllanthus rufuschaneyi after Rufus Chaney. Chaney is a retired researcher who has worked for years on developing argomining. It therefore seemed an appropriate choice. ‘We asked for his permission and he felt very honored,’ addsBouman.
Bouman, R.; van Welzen, P.; Sumail, S.; Echevarria, G.; Erskine, P.D.; van der Ent, A., 2018. Phyllanthys rufuschaneyi: a new nickel hyperaccumulator from Sabah (Borneo Island) with potentioal for tropical agromining. Botanical Studies 59:9. https://doi.org/10.1186/s40529-018-0225-y
How do you test whether plants are good metalminers?
Whether a plant is good at extracting metal or not is not reflected in the appearance of the plant. There are therefore several tests that researchers perform on a series of plants to determine which species are potentially interesting. The biologists who examined P. rufuschaneyi did this, for example, by testing the leaf with dimethyl-glyoxime paper. This paper reacts with any metal present and discolours.
Most plants that may be interesting for agromining can now also be recognized by means of a special scanner for herbarium material. The scanner searches for high concentrations of metal in the dried material. To see which plant absorbs the most metals, researchers process small pieces of leaf in the lab to determine the individual concentration of metal.