There’s a scene in The Discipline Of Odette in which one matron is advising another about a way in which she can punish her daughters more frequently and severely:
“But why don’t you use nettles?” Madame Lacaille asked.
“Why, yes, the governess of my daughters came up with that idea. Nettles prick and produce a cooking heat that lasts a long time, without causing any wound or cut.”
“But where can you buy nettles? I wouldn’t know where to look.”
“Why, in all the shops that carry whipping articles, of course; where do you buy your birch rods and your martinets?”
“I rarely use the birch, but when I do, I go to a novelty shop, and I don’t think I’ve ever seen nettles there.”
“Haven’t you ever gone to the Rod and Martine, on the Rue Saint−Honore?”
“I confess my ignorance.”
“Well, go there, then. Besides, it’s quite a curious shop. They sell all kinds of material you’d find in a house of correction: whipping horses, special benches, paddles, birches, martinets… and nettles too. They’re sold in carefully tissue−wrapped packages so the stems won’t prick the fingers of the buyer. Only, I’ll admit there’s just one inconvenience: nettles must be fresh; after 24 hours, even if you keep them in water, the leaves fade and have no effect. But the shop has a very good delivery service. So I’ve subscribed to it, which means that every other day they deliver four bouquets, enough for four punishments. With the two girls I have, I often need that much.”
“Why, I was absolutely unaware of such a thing,” Madame Delage delightedly exclaimed.
The Discipline of Odette is an erotic classic of variable attribution, like many such. But I found this excerpt at Rollin Hand’s Disciplinary Tales, via Chross.