I had an editor early in my career who repeated her grandmother’s favorite oath any time the culture served up fresh evidence of the dire and depraved straits America was plunging into.

“Fall of Rome. Fall of Rome.”

It’s a phrase that came to mind often in the two hour and 43 minute “American Honey,” an odyssey about poverty, predators and prey in Meth Mouth America.

Open bottles in every car ride, joints passed back and forth from driver to passengers, people at the bottom preying on anybody empathetic or gullible enough to fall for their spiel. This is what American desperation looks like, a “Winter’s Bone” that’s gotten a grip far beyond the Ozarks.

And everywhere, in every motel parking lot or backwater backstreet, we spy a sea of unsupervised children raising themselves because their self-involved lowlife parents (almost all white, BTW) can’t be bothered to stop drinking, line-dancing and lighting up a pipe to do it themselves.

If this is how the heartland’s hardest up are living and raising their kids, “fall of Rome. Fall of Rome.”

“Honey” is about a dead-end teen trapped raising her worthless trailer-trash mother’s children in the company of Mom’s groping/handsy ex-boyfriend. Star (Sasha Lane) leaps at the chance when she’s recruited to join a traveling band of hustling, drinking, partying kids who invade town after town, “selling magazines” and stealing and doing anything else they can to make a buck.

Star is lured by the flirtatious “Jack” (Shia LaBeouf) and the free-spirits of the “Tornado Publishers LLC” sales squad — kids “nobody will come looking for,” kids covered in tattoos and piercings, kids who to a one must have a sadder-than-sad family history that made them this desperate and vulnerable.

But the only sad stories they tell are fiction — about losing Dad “in Iraq,” or Mom “to cancer,” or “trying to win a prize so I can go to college and make something of myself.” Their real stories they keep to themselves.

It’s all a lie, and the prickly Star isn’t exactly a natural at it. Training with Jake, she bristles at his ad lib fibbing and is rude to his “marks.” She’ll never make a salesgirl who keeps Krystal, the sexy boss lording over this brood (Elvis granddaughter Riley Keough of :Mad Max: Fury Road”) content and flush.

But love might transform her. Jake is certainly willing to play that card, if it’ll make her a success. And as the kids and their handlers trek from Texas to Kansas, North Dakota to South Dakota, singing along to filthy rap and catchy pop (including the Lady Antebellum song that gives the movie its title), trotting out their rituals (beating up the kid with the worst sales, streaking, setting off fireworks for every occasion), we see Star evolve into someone with that potential.

And we see a love story that plays like two kids in heat, but finds a tender center thanks to Star’s sweet and nurturing nature.

Writer-director Andrea Arnold doesn’t make short movies. But even her breakout film “Fishtank” and her Kaya Scodelario “Wuthering Heights” are but warm-ups for this langorous, sensual film. It’s basically a 100 minute film padded out to 2:43.

But surprisingly, it never loses our interest as we wait for Jake’s inevitable moment of showing his hand, wait for the violence that surely awaits the reckless Star as she gets into semis at truck stops and roughneck pickups in North Dakota’s Bakken shale oil fracking fields, or hitches a ride with a trio of rich good ol’boys in cowboy hats (look for Will Patton) who introduce her to mescal.

There’s a fantastical unreality to a lot of this– the lack of conflict within the group, the threatened “punishment” of non-performers, the general lack of cell phones in a generation grafted to them, the utter absence of police, who would almost surely stumble across people this loud, this unruly in stores, at motels, this committed to under-age drinking and drug using.

The dreadlocked newcomer Lane is more sexual than sweet or conventionally beautiful. But she makes the character’s innate goodness peek through the hard shell Star has grown to cope with the misery of her life. We meet her dumpster-diving to feed her siblings. The adults in her life are that worthless.

We grimace when she ditches the kids with her lout of a mother. But with every honeybee she saves from a pool or trapped inside a window, with every kind stranger she does her damnedest not to cheat, with every moment she recognizes “These people are just like me — just as bad off” Lane lets us see Star learning and makes us hope that she will complete her education before something in this “life” she’s entered into puts her in harm’s way.

If Johnny Depp spent too many years taking roles that didn’t force him to cut his hair, LaBeouf has made it a point, post-“Transformers” — to tackle more interesting indie fare, especially if it has intense sex scenes in it. He’s more interesting as Jake — all ill-fitting suit and hustler patter, and under the thumb of the mature and in-control Krystal — than he’s been in years.

Arnold has made a bleak romance that shimmers with hope, an overlong odyssey that we smell just as surely as we feel. The lengthy scenes in the van, traveling from city to city, make us taste the close quarters that prevent rather than promote conflict and imagine just what this crowded circus’s scent must be, even as we wonder who, in this day and age, would buy magazine subscriptions, especially from these ‘hood rats.

But if this is how they live in the moment, and this is the limit of their shrinking horizons, when not one of them has ever been asked “How do you see your future?”

“Fall of Rome. Fall of Rome.”

MPAA Rating:R for strong sexual content, graphic nudity, language throughout, drug/alcohol abuse-all involving teens

Cast: Sasha Lane, Shia LaBeouf, Tom Paxton

Credits:Written and directed by Andrea Arnold. An A24 release.

Running time: 2:43