Question

In what respects are lichens unusual plants

Answer 1

Lichens are regarded as unusual because they can grow on any surface e.g old walls etc.
Lichens are symbiotic organisms that have their formation through the symbiotic relationship of fungi and algae. They are not nature born. They can be found as white or yellow patches on old walls and many other surfaces.

Answer 2

Lichens are unusual plants because:

1. Lichens are dual organisms. They are symbiotic associations between two entirely different kinds of microorganisms - a fungus and a green algae.

2. Their appearance and behaviour is different from the component organisms. So they are considered to be organisms on their own. They are given generic and species names. But for taxonomic purposes they are regarded as a special group of fungi and known as lichenised fungi.