Lichens range from a dark and gelatinous crust
Or things daubing rocks with rosettes of brown rust
To the tufty and leafy and curly and pendent
Where the right kind of atmosphere's clearly ascendant.
What’s more, Science checks on the planet’s bad breath
When it maps every spot choking lichens to death
Since no few from this realm of discreet symbiosis
Are unable to face fossil fuels’ halitosis.
Hardy fungus-and-algae affairs brave the cold
Of regions where grass finds it tough to take hold,
Among them, although it may seem barely credible,
Examples once proved, at a pinch, to be edible.
There’s around fourteen hundred distinct UK types,
Some long ago used to dye tweeds and fill pipes
(Mummy-stuffing as well, in a land more exotic)
While a number boast powers billed as antibiotic.
Sorry, Golden Hair, Green Powder, Mustard and all,
Nice names, if not those for which verse-writers fall,
As they're caught by what gives them a fresh rhyme in ‘ottle’
And that's P. saxatilis, or plain Common Crottle.