"...li metto in un sacchetto di carta, magari insieme ad una mela o ad una banana matura..."
"...l'avocado comincia ad aumentare la respirazione..."
"...ma la pianta che lo originò non venne mai trovata ed è tuttora ignota la provenienza..."
Besides that pebbly-skinned green fruit, though, what are those strange words ad and ed?
Che Cacofonia!
In the Italian language la d eufonica (the euphonic d) is an euphonic (agreeable in sound; pleasing to the ear) phenomenon, in both spoken and written Italian, in which the letter "d" is added to several different participles if their vocalic interplay with the word immediately following (which also starts with a vowel) creates cacophony or difficulty in pronunciation. In modern Italian la d eufonica occurs in three cases:
—with the preposition ad (a)
—with the conjugation ed (e)
—and rarely with the conjugation od (o)
While in the past, it was popular also in the forms:
—ned (né)
—and ched (che)
Today there are no iron-clad rules regarding its use; modern Italian style manuals recommend using la d eufonica only when encountering identical vowels, or when certain phrases simply sound better: "ad esempio." Another instance is "lui ed io," which is suggested instead of the horrible-sounding "lui e io". In general, "ed io" (pronounced "edd io") is better than "e io". Other cases are left to the discretion of the author or speaker.
Music To My Ears
La d eufonica occurs because Italian speakers try to avoid sounds that are disagreeable, either to themselves or the listener, or that are difficult to pronounce. A similar case is the elision of the first vowel in the form of "ne è" into "n'è".
From an etymological point of view, the particles ad, ed, and od derive from the Latin ad, et, and aut. The silent "t" sound would have been transformed into a vocalized "d" whenever those words preceded another that started with a vowel—an intervocalic position, for those interested in Italian linguistics.
Mi Raccomando: When To Use La D Eufonica
Community members of the About.com Italian Language Forums frequently ask about usage guidelines regarding the la d eufonica:
"I thought that one should write 'ed' instead of 'e' when the following word begins with a vowel. Was that an incorrect assumption?"
"With the constructions: ed essere or ed io is it correct to pronounce the "d"?"
"I've seen the words for 'and' (e), 'or' (o), and 'to' (a) change to ed, ad, and I don't know about od (just a guess). Does this change occur with all vowels?"
Many excellent answers have been provided, but two in particular stand out:
"Write (and pronounce) ed for e every time the following word begins with e; ad for a when it begins with a; od for o when it begins with o. I would write (and pronounce) ed, ad, and od when too many vowels would otherwise be found in a row. Examples include: "lei ed io" and "una linea od altri segni."
"You are bound to find la d eufonica in many contexts that grammarians don't recommend."
But probably the best advice for determining when to use la d eufonica is this:
"Inserting a 'd' in front of another vowel [when the next word does not begin with the same vowel] is allowed but not mandatory, and it is better avoided. For stylistic reasons, however, a 'd' is expedient when too many vowels would otherwise meet so you'd need to untwist your tongue afterwards: 'Diatomee ed augellini' or 'Antinoo od Automedonte' or 'Dulcinea ad Eurialo.'"
