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92 M. Mleczek et al.

accumulate Cd than Zn; the different uptake of Cd and Zn shows that there are basic
differences in the mechanism of accumulation of both metals in hyperaccumulators
(McGrath et al. 2006). Thus, increased selection for traits of interest may help
to improve the phytoremediation capacity of hyperaccumulators (McGrath et al.
2006). It is necessary to underline that also other species of Thlaspi have a
good accumulation capacity and remediation capability: T. goesingense and
T. ochroleucum hyperaccumulate Ni and Zn, while T. rotundifolium hyper-
accumulates Ni, Pb, and Zn (Rascioa and Navari-Izzo 2011).

5.4.1.2 Pteris vittata (Pteridaceae) and Reynoutria sachalinensis
(Polygonaceae)

The first defined arsenic hyperaccumulator, Pteris vittata L., was described by Ma
et al. (2001). This plant may accumulate as much as 2.3 % arsenic in the fronds
1
when grown in soil containing 1.5 g kg , and is very efficient in removing arsenic
from all fractions of the rhizosphere soil (Silva Gonzaga et al. 2006; Antosiewicz
et al. 2008). The plants produce a relatively high biomass under favourable climate
conditions, accumulating (from relatively low As concentration in the soil) 22 g As
kg 1 in the frond dry weight, with a bioconcentration factor of 87 and a removal of
26 % of the initial As present in soil (Ma et al. 2001; McGrath and Zhao 2003).
Other As-hyperaccumulating fern species have been identified more recently (Zhao
et al. 2003). Great potential for phytoextraction has also been reported for
Reynoutria sachalinensis (Polygonaceae). This plant accumulated As up to
1.9 g kg 1 dw in shoots and up to 0.43 g kg 1 dw in roots, and drastically reduced
As concentrations in soil from up to 600 to 6–9 mg kg 1 dw after 5 years of
cultivation and harvesting (Antosiewicz et al. 2008).

5.4.1.3 Fagopyrum esculentum (Polygonaceae)

Although Pb is largely an immobile element in soil and its extraction rate is limited by
solubility and diffusion to the root surface, common buckwheat (Fagopyrum
esculentum, Polygonaceae), the first known Pb hyperaccumulator species with high
biomass, can accumulate upto4.2 mg kg 1 dw ofPb in theshoots (Tamura etal. 2005).
Amending the soil with the biodegradable methylglycine diacetic acid (MGDA)
resulted in a fivefold increase in the Pb shoot concentration. This relevant finding
qualifies this species as an excellent candidate for remediating Pb-contaminated soils.

5.4.1.4 Phytolacca acinosa (Phytolaccaceae)
This plant, which grows rapidly and has substantial biomass, has been considered to
have potential for use in phytoremediation. The plant is able to accumulate Mn to
19.3 g kg 1 dw when grown on Mn-rich soils (Xue et al. 2004).