On St. Patrick’s Day, many people reach for a beer that’s green. But one that is black is a much more authentic way to go. Dark, dry and roasty, stout is Ireland’s national brew.

There is a common misperception that dark beers are heavy. In truth, color reveals very little about the weight or character of beer. Irish stouts in particular are far from being a “meal-in-a-glass.” These are beers built for long sessions of drinking. They range in strength from 4 to 5 percent alcohol, the same as a standard American lager. They have only a few more calories than a light beer. And the nitrogen gas with which many of them are dispensed results in lower carbonation for a less filling quaff.

Guinness Draught is obviously the elephant in the room of Irish stout. That familiar sight of pitch blackness capped by a creamy head of cascading foam is enough to make any beer lover salivate. Guinness is an extraordinarily dry and light-bodied beer — some might even describe it as thin. That lightness accentuates the intense bitterness and almost burnt flavors of roasted barley. Flavors of dark-roasted coffee beans and hints of cocoa give it character. Cans and bottles of Guinness Draught have the nitrogen “widget” so you get that same creamy pour whether you drink it at a bar or at home.

Sometimes the enjoyment of one beer over another comes down to intangibles. It’s the subtle differences that you can’t quite put a finger on that lift one up. This is the case with Murphy’s Irish Stout. It has the same light body and bitterness as Guinness. The coffee beans and cocoa are there, too. But little differences make it a more enjoyable beer, in my opinion. The burnt flavors are slightly less pronounced. There is a touch more sweetness to balance the bitter. The cocoa is very slightly more present, giving faint, chocolaty, background notes. Murphy’s also has the widget in the can.

If you want a more full-flavored stout experience from Ireland, look to O’Hara’s Irish Stout from Carlow Brewing Co., one of a growing number of Irish craft brewers. The aroma gives the first clue that this beer is not like the others. It’s richer and redolent of coffee and bittersweet chocolate aromas. The flavor follows suit. It’s bitter, dry and roasty as the style demands, but a bigger hit of coffee and chocolate gives it a more complex profile. The body is bigger, as well, making for a more satisfying mouthfeel as it moves across your tongue.

If fuller-flavored, fuller-bodied beers are more to your liking, try Guinness Foreign Extra Stout or O’Hara’s Leann Folláin. These export-style stouts can be thought of as stronger, richer versions of the standard Irish stout.

Guinness has been brewing Foreign Extra Stout since 1801. At 7.5 percent alcohol, it is almost twice as strong as Guinness Draught. This is reflected in the medium-full body and light warming sensation of alcohol. The flavor is a blend of fruit, roast and moderate brown-sugar sweetness. Notes of raisin and dried cherry give an almost vinous counterpoint to coffee and bitter cocoa. Hop bitterness is fairly high and lingers into the finish, but the body and sweetness keep it from going over the top.

O’Hara’s Leann Folláin leads off with dry, roasted malt and bitter chocolate flavors that bring to mind the cookie part of an Oreo. This is offset by moderate sweetness and fruity hints of golden raisins. Bitterness is fairly high, but the additional sweetness and body make it seem lower than O’Hara’s Irish Stout. Herbal/earthy hop flavors add a little something extra.

A whiskey-barrel-aged version of Leann Folláin currently has very limited availability in the Twin Cities. The whiskey and wood add an extra layer of complexity, but the spirit remains subtle. Unlike some barrel-aged beers, it doesn’t feel like drinking a shot.

Michael Agnew is a certified cicerone (beer-world version of sommelier) and owner of A Perfect Pint. He conducts private and corporate beer tasting events in the Twin Cities, and can be reached at michael@aperfectpint.net.