Plant, herb

Phytolacca americana L.

American pokeweed

A large perennial herb that hyperaccumulates manganese in its leaves and accumulates cadmium. It combines accumulation with high biomass, which is rare; accumulation shows, however, only where soil is rich in available manganese.

Huw Williams (Huwmanbeing), Public domain

How it works

Mechanisms: hyperaccumulationphytoextraction
Native range: North America, including the south-eastern United States

Contaminants

Contaminant	Evidence	What was shown
Cadmium	field	Plants sampled at three contaminated sites in China: on average 42 mg/kg Cd in leaves, maximum 402 mg/kg; in hydroponics up to 637 mg/kg in aerial tissues at 100 µM Cd. Accumulation is a constitutive trait and is linked to transpiration (Liu et al. 2010). Liu et al., Cadmium accumulation and distribution in populations of Phytolacca americana L. and the role of transpiration, Chemosphere 78:1136, 2010
Manganese	laboratory	Wild plants in the south-eastern United States: about 2,000 µg/g Mn dry weight, against 50–450 µg/g in other species at the same site. In nutrient solution up to 8 mM Mn, leaves exceeded 32,000 µg/g (3.2%) within three weeks (Pollard et al. 2009). Pollard et al., Manganese hyperaccumulation in Phytolacca americana L. from the southeastern United States, Northeast. Nat. 16(sp5):155, 2009

Contaminant

Evidence

What was shown

Cadmium

field

Plants sampled at three contaminated sites in China: on average 42 mg/kg Cd in leaves, maximum 402 mg/kg; in hydroponics up to 637 mg/kg in aerial tissues at 100 µM Cd. Accumulation is a constitutive trait and is linked to transpiration (Liu et al. 2010).

Liu et al., Cadmium accumulation and distribution in populations of Phytolacca americana L. and the role of transpiration, Chemosphere 78:1136, 2010

Manganese

laboratory

Wild plants in the south-eastern United States: about 2,000 µg/g Mn dry weight, against 50–450 µg/g in other species at the same site. In nutrient solution up to 8 mM Mn, leaves exceeded 32,000 µg/g (3.2%) within three weeks (Pollard et al. 2009).

Pollard et al., Manganese hyperaccumulation in Phytolacca americana L. from the southeastern United States, Northeast. Nat. 16(sp5):155, 2009

Limits

In Europe it is an alien species: growing it for remediation carries a risk of spread that must be assessed case by case. At high Mn concentrations the plant excludes part of it by precipitating it as phosphate on the roots (Dou and Qi 2023). The sources consulted contain no field trials with a mass balance of metal removed.