We’re putting these Austinite sisters, whose name is pronounced with a hard “G”–like gutsy or girls, they say–under the Americana umbrella. iTunes calls them singer-songwriters. If you listen to a few samples, though, you’ll wonder why country doesn’t come up. From Tiffani Ginn’s buzz-saw voice and sister Brit’s more delicate high harmonies, to the basic electric-and-acoustic strings dominating the instrumentation, to the hard honky-tonk themes of many of their songs, the Ginn Sisters are wrapped up in country’s Texas roots.

They diverge from country music in their total avoidance of sentimentality and ease. The recent Ginn Sisters album Blood Oranges (whose cover shows red orange halves being crushed by a pair of hands) includes grimly detailed investigations of the span of time in which substance abuse drives someone off a cliff. In “Down the Drain” (“you’ve got everything goin’ for you, right down the drain”) and “Hard Fall” (“it’s a hard fall from Saturday night”), the figure involved is a friend or lover of the song’s female narrator, but just as often the narrator herself is a full participant in a bad situation. “Get It and Go” (“there’s only one thing that you came here for”) is a remarkable dissection of an end-stage relationship in which the physical component still makes up a kind of ongoing addiction. It’s a difficult theme for a songwriter to carry off without making either of the parties into the villain, but that’s just what Tiffani Ginn, who writes most of the duo’s material, does here.

Many of the sisters’ songs have a tone somewhere between mournfulness and mature pessimism, but others are more wryly upbeat. These are associated with another non-country aspect of the Ginn Sisters’ music, one most effective in live shows–Brit Ginn’s flute and occasional melodica, a sort of accordion stretched out to the dimensions of a clarinet (with a keyboard rather than valves). It puts in an appearance at least a couple of times per show, adding a humorous touch and a musical counterpart to the sisters’ extension of country music’s lyrical-emotional frameworks.

The Ginn Sisters work slowly, releasing new music only once every several years–noteworthy in the highly competitive Austin scene, where every band tries to break out of the pack. Blood Oranges is now three years old, and I’m anxious to hear what this quite ambitious duo is coming up with next. They’ve played several good shows at the Ark, and they make a return visit Wednesday, August 12.