Mother to child: Oh look, darling, it's a Petticoat Fungus!
Child to mother: No, it isn't, mother. It's a Paneolus Sphinctrinus.
In fact, such a conversation is likely to be the other way round. The child's mother and me and my generation, to the extent that we knew anything at all about fungi, only knew them by their scientific names. But recently, the British Mycological Society, in an attempt to popularise fungi, has given many of them vernacular names. So what I know as P.sphinctrinus (an hallucinogenic mushroom which grows on or very near dung) is, to a new generation, a Petticoat Fungus, so named from the frill that decorates the rim of the cap.
Last Sunday, I was completely at sea as the foray guides named species using the new English nomenclature, and felt like some kind of poser when I had to ask for the scientific names. For example, what they called a Brown Rollcap looked to me like Paxillus involutus, which of course it was.
When I first looked at dragonflies, they only had scientific names. Since then, they have acquired English names, with the result that people now take a lot more interest in them. When my old mate Roger B came to visit, I pointed out a Ruddy Darter to him, and he was baffled. Then, seeing it better, he said, "Ah, yes, Sympetrum sangineum."
It's all very confusing, so if you will excuse me, I am off to gather a few Petticoats and make an infusion. Don't tell the gendarmes.