Heavy Metal Plant LIVES ON ROCK

If plants did rock out at concerts then the one above would definitely be Bornmuellera to be wild. Some plants like to be in sunlight in well-drained soils. Others need moist potting and the shade. Bornmuellera baldaccii in contrast likes ultramafic soil. This is soil made from the kind of igneous rocks, similar to the rock you’d find in the mantle. When it breaks down into soil, it’s low in silica but high in heavy metals like chromium and nickel. It’s the kind of soil that would normally be toxic to plants.

As Cecchi et al. explain, Bornmuellera baldaccii can live in these conditions because it is no ordinary plant, it’s a Nickel hyperaccumulator. Its ability to survive in toxic environments could make it useful to help clean up polluted sites. Cecchi’s paper also introduced me to the concept of phytomining. If a plant can hyperaccumulate nickel then it’s holding on to a valuable asset. Harvesting it and burning it would yield nickel-rich ash – which you can process for nickel.

It’s not a trait that every plant has, but some others do. One is Leptoplax (Peltaria) emarginata. Until now people thought it was related to a non-hyperaccumulator plant in the tribe Thlaspideae. The hyperaccumulator abilities in L. emarginata led to a molecular study that showed it was relative to Bornmuellera baldaccii. It means it’s in a different tribe, the Alysseae.

Getting the family tree right means that we can have a better idea of what happened when. Cecchi et al’s study also shows that hyperaccumulation wasn’t a one-off event. It seems that hyperaccumulation is a skill that can be evolved or lost by plants in the Alysseae tribe to take advantage of ecological niches when they happen.

It seems that Bornmuellera baldaccii‘s ancestors chose to take the hard way to success so they could live among hard rock. If hyperaccumulators can be used to clean up messes, then they could have a long and profitable relationship with heavy metal.

You can read the full article for free at Annals of Botany.

Cecchi L., Gabbrielli R., Arnetoli M., Gonnelli C., Hasko A. & Selvi F. (2010). Evolutionary lineages of nickel hyperaccumulation and systematics in European Alysseae (Brassicaceae): evidence from nrDNA sequence data, Annals of Botany, 106 (5) 751-767. DOI: 10.1093/aob/mcq162