plants

as a chemical defence against herbivory

Thlaspi caerulescens is one of several plant species known to

accumulate heavy metals in excess of 2% of their above ground plant

biomass. The reasons for hyperaccumulation are unknown, but

several studies conclude that it may be a plant chemical defence.

This has been of interest to biologists because these metals are

usually toxic. The accumulation of these metals may serve as a

model for coevolution. We examined the effects of zinc

hyperaccumulation in Thlaspi on Xanthomonas campestris and found

that the plants containing zinc thrived when inoculated with this

bacteria, while plants not containing zinc showed signs of

There are several wild plant species that have the ability to

accumulate high quantities of heavy metals in their above ground

biomass, up to three percent or more. Many of these plants are

found in the Brassicaceae family throughout Europe and the British

Isles. These plants thrive on mineral outcrops with calamine and

serpentine soils rich with high levels of zinc, cadmium, and nickel

(Baker et al, 1994). Several theories have been advanced on the

. . .
Some common words found in the essay are:
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Approximate Word count = 1199
Approximate Pages = 5 (250 words per page double spaced)