In article <4krbos$5u8 at altrade.nijmegen.inter.nl.net>,
Frits v/d Laan <f.vd.laan at inter.nl.net> wrote:
>I would like to get any information about plants that are known to
>indicate at a early stage anything to do with there environment,
>shortage or to much of nutrician N, P, K, Mg etc. or are sensitive for
>or atract insects earlier than most plants.
Lichens are indicators of air pollution. Unlike vascular plants,
they don't have any way to get rid of toxins, so they are
particularly sensitive to environmental pollution.