I bought a Plum Pudding to have as a Christmas dessert. It contains no plums or prunes. I've checked a number of recipes on the internet and all but one were also devoid of plums in any form.

Does anyone know why this dessert is called Plum Pudding when it contains no plums?

I understand that this dessert possibly originated as a harvest enjoyment and was first made with wheat and dried fruits. Does anyone know why or how it became a traditional English Christmas treat?

I don't know the answer to your question, Brewers dictionary of Phrase and Fable has nothing. These days in Britain we tend to call it Christmas Pudding rather than plum pudding. Even the traditional inclusion of things such as a silver coin (sixpence) and a ring has mostly gone.

According to the Oxford English Dictionary "plum" can mean "A dried grape or raisin as used for puddings, cakes, etc." It thinks "This use probably arose from the substitution of raisins for dried plums or prunes as an ingredient in plum-broth, -porridge, etc. with retention of the name 'plum' for the substituted article." The earliest quotation is from a mock sermon written around 1660:

"But there is your Christmas pye and that hath plums in abundance. ... He that discovered the new Star in Cassiopeia ... deserves not half so much to be remembered, as he that first married minced meat and Raisins together."

So plum-puddings may have been made with plums (or more probably prunes) once upon a time. Then we substituted raisins but we still called them plums. Then, somewhere along the line, we stopped calling the raisins plums but we still called the pudding a plum pudding. Then, as Sue says, we started to call the pudding Christmas pudding.

And of course the "minced meat" (or mincemeat as we call it today), mentioned in the OED's quotation, isn't what we'd call "meat", either.

As far as I've found out plum pudding has never been made with plums it has always contained raisins and other dried fruit because in history these were always available cheaper than other fruit. I believe it's called Plum Pudding because of the process in which it is made or a process that the fruit goes through.

I have a supplementary question. It's also called plum duff. What is a duff?

Lest we transfer this to the joke section, it brings greater meaning to the expression get up off your duff!

I'm still working on that spotted, well you know...Richard!
Mind the custard!

Islingtonian, don't know if this will help to answer your question:

"Incidentally, lord is from the Old English hlafeweard or "loaf keeper" and lady is from hlaefdiger or "loaf kneader". The -dige portion of hlaefdiger is related to dough and duff. The latter word is the northern English form of dough and is found in the names of those peculiarly English puddings plum duff and figgy duff."

I think a "duff" may be a bread roll (like a roly-poly)which is studded with fruit, but it also seems to refer to a bread pudding, made with fruit, which is steamed or boiled. So, the derivation from "dough" seems to fit.

I have also found that Figgy Pudding and Figgy Duff may contain no figs. It seems that "fig" is the common term for raisin in Cornwall.

A raisin, it seems, is a quintessential example of, "What's in a name?" Plums, figs, they are all "raisins". Veddy confusing. Amazing what one can learn from recipes.