“You gotta learn to drive,” Dad says at one point to his daughter looking at him warily from the drivers seat.

“I’m ten!” she exclaims.

Ryan Kiera Armstrong, now just 13, who has already created a notable career in horror world from the “Firestarter” remake to “American Horror Story: Double Feature,” portrays young Bea in that scene and does so with the same serious confidence Shipka and grace had at her age in “Mad Men.” (Plus they kind of look alike).

But the rest of the cast of the modest indie is kind of mind-blowing; one set of grandparents is played by Jean Smart and Brad Garrett; the other by a chain-smoking Jacki Weaver and Chris Mulkey. 

Bea’s aunt and uncle, who take her in for a while are Alexandra Daddario of “White Lotus” and Reid Scott of “Veep”; Bea’s love interest is Charlie Plummer (John Paul Getty III in “All the Money in the World”).

Shipka, once the story catches up to her high school years, stands tall among them, with the kind of knowing, world-weary air of a young Kristen Stewart.

It’s a carefully told story, so as to never make fun of the neurodivergent, but open enough to include humor in its very human approach.

It rings true because it’s written very close to life; director Matt Smukler is an uncle of the young woman on whom the story is based (and hence the Reid Scott character in the film). He also previously made a documentary about the same remarkable young woman (confusingly also named “Wildflower”).

Screenwriter Jana Savage adds a lot of the humor to the warm story. And though this is Smukler’s first feature, he has a lot of experience doing commercials, including some of the most memorable progressive ones, such as the mixed-couple Cheerio’s ad). From it all, he’s picked up a few things about framing, pace and succinct storytelling.

“Wildflower” threatens to become its most conventional when it sways from its unique family setting to the usual high school drama that comes with the usual mean girls and overbearing counselors. 

Yet it’s Shipka’s strength, and maybe our familiarity with her own growing up on screen, that helps make this “Wildflower” thrive as an enjoyable yarn.

“Wildflower” is available for rent, purchase or streaming via subscription on Apple iTunes, Vudu, Amazon Video, Google Play and YouTube.