An article with the headline "Ferns native to Singapore able to filter out arsenic" appeared in the Straits Times last Saturday. Any news that talked plant in the press will get my attention, especially on ferns, an often neglected group in the plant kingdom. The two ferns indicated were the Silver Fern and Brake Fern. Though their botanical names were not mentioned in the report, the Silver Fern is likely to be Pityrogramma calomelanos while the Brake Fern should be Pteris vittata. Based on my observation, Pteris vittata is far more common in Singapore than Pityrogramma calomelanos.

Arsenic is a naturally occurring compound though it is used by certain industries. Exposure to arsenic above certain level was reported to be correlated with health problems in human. The presence of arsenic in high concentration in water is an issue in some part of the world. Fortunately, we do not have such situation in Singapore.

The hyper-accumulation of arsenic by these ferns is not a new discovery in science. It has been reported for some years now by researchers in different parts of the world. At first, I thought the first report related to this property in Brake Fern was published in the journal Nature by a group of researchers from the University of Florida (USA) 14 years back in 2001 [1]. But, another team in China was ahead of the race by a year in 2000 [2]. Following these reports, more publications were released affirming these findings over the years. In 2002, similar property was observed in the Silver Fern by a multinational research team based on the Silver Fern collected in Thailand [3].

Both ferns had grown in my pots but right now, they had become the casualties of the exterior painting work going on at my apartment block in the last few weeks. Apparently, they were highly sensitive to the chemicals emitted by the paint and all had succumbed to the toxic particles emitted by the paint in the air. In general, Silver Fern looks prettier than Brake Fern as a decorative plant. Both of them are water-hungry creatures, taking up water relatively faster when compare to other plants in my pots. However, Brake Fern seemed to be more drought resistant than Silver Fern; thus accounting for its presence in drier areas while Silver Fern was seen mostly around water-logged habitat.

References:

[1] Ma LQ et al. A fern that hyperaccumulates arsenic. Nature 2001 Feb 1;409(6820):579. | Abstract |

[2] Chen T B, Wei C Y, 2000. Arsenic hyperaccumulation in some plant species in South China. Proceedings of International Conference of Soil Remediation. Hangzhou, China, 194-195.

[3] Francesconi K et al. Arsenic species in an arsenic hyperaccumulating fern, Pityrogramma calomelanos: a potential phytoremediator of arsenic-contaminated soils. Sci Total Environ 2002 Feb 4;284(1-3):27-35. | Abstract |