NEW YORK • Brad Thomas Parsons does not seem like a bitter guy. Garrulous and friendly, he is a well-liked regular at several restaurants and bars in his Brooklyn neighbourhood, Carroll Gardens.

He is Mr Bitters in the cocktail and spirits worlds.

He wrote Bitters, a 2011 book that took a long, loving look at those little bottles whose contents are dashed into drinks.

Some credit its success with helping to seed the current bumper crop of cocktail books.

For his follow-up, he is back on the bitter beat. Amaro: The Spirited World Of Bittersweet, Herbal Liqueurs (Ten Speed Press) takes on a genre of distillations that is primarily native to Italy.

As with Bitters, the book is ideally timed: Many Americans in the last few years have discovered the bracing pleasures of drinks such as Campari, Aperol, Cynar and even the acerbic Fernet Branca.

"I think we're in a place with amaro that we were with bitters four or five years ago, where more and more bottles are popping up," Parsons said.

The same could be said of his apartment, where one wall is taken up by shelves laden with liquor bottles, a great many of them amari he has brought home from Italy.

He has the usual suspects, like Averna, Lucano, Meletti and Ramazzotti, but also obscure specimens such as Amaro Silano, a Calabrian liqueur that has conifer trees on the label yet tastes of oranges; and Kapriol, a rare, clear amaro that tastes of juniper.

Like most Italian liqueurs, the last two are regional specialities. The amari explosion in the United States notwithstanding, most brands do not leave the old country.

Parsons recalled a visit to a liquor store in Rome: "They had a wall of amaro, two or three shelves long. So much of it I'd never seen before."

For the 47-year-old, part of the challenge of researching the book was figuring out what he was writing about.

Beyond the generally accepted notions that amari are composed of alcohol (usually neutral spirits), sugar and a proprietary mix of herbs and botanicals, it gets confusing. The Italian government has not legally defined what an amaro can or cannot be, nor what makes a fernet - a sub-category of amaro - a fernet.

Though the word amaro means bitter, most Italians think the group of liqueurs they call "bitters", including Campari and Aperol, are not in the same school.

Some Italian makers insist that amari can be made only in Italy, though some American microdistillers have started to bottle their own interpretations.

Parsons takes a democratic approach. "I see it as a big umbrella term to cover the German tradition of bitter liqueurs, the French tradition of amers, the Mexican fernet," he said.

He quoted Mr Alex Bachman, a partner at Billy Sunday, an amaro-heavy bar in Chicago: "We could pick weeds from a sidewalk in Chicago and call it fernet."

NYTIMES