What especially fascinates me about lichens is that their phenotypes (see the Beaver’s Tale) look nothing like a fungus—nor indeed like an alga. They constitute a very special kind of ‘extended phenotype’, wrought of a collaboration of two sets of gene products. In my vision of life, explained in other books, such a collaboration is not in principle different from the collaboration of an organism’s ‘own’ genes. We are all symbiotic colonies of genes—genes co-operating to weave phenotypes about them.
