It’s easy to forget that movies are — or used to be — physical things.

Streaming being the norm these days, the original, tactile, very much physical nature of the movies tends to get lost, especially as the flood of streaming content turns our living rooms, phones or laptops into unending screening rooms, albeit pretty lousy ones.

But some movies call out for that physical connection, projected on actual film in an actual movie theater, the hum of a carefully maintained projector a whirring second soundtrack. Or maybe the only soundtrack.

All this pontification is a way to introduce this week’s screening of experimental filmmaker Nathaniel Dorsky’s seven-film, silent, 2-hour-and-20-minute opus “The Arboretum Cycle,” playing at The Strand Theatre in Rockland on Sunday. A legend in the rarified world of experimental American film, Dorsky is yet unknown to most. Maybe a description of “The Arboretum Cycle” will help explain why.

The films making up the “Arboretum Cycle” are about plants. That’s it. Specifically, the seven silent shorts, titled “Elohim,” “Abaton,” “Coda,” “Ode,” “September,” “Monody” and “Epilogue” represent Dorsky’s experience meditating upon the way that light interacts with the teeming vegetation in San Francisco’s Strybing Arboretum. Lingering shots carry through the seasons, the changing light and flowering and wilting plants the only narrative.

“This is an artist-driven, community-driven screening,” says Maine-based filmmaker Benjamin Greené, who was instrumental in bringing Dorsky’s experimental epic to us. “None of these partners are going to make any money on this.”

And while Skylar Kelly, founder of Portland’s own haven for 16mm film projection and preservation Kinonik concedes that “The Arboretum Cycle” isn’t going to do Marvel business, it’s impossible to listen to him and Greené talk about the process of bringing Dorsky’s film to Maine and not get at least a bit swept up.

As Kelly explains, Dorsky’s screening requirements are almost as stringent and experimental as his films. “Dorsky has to approve all screenings, which have to be at the proper frame rate of 18 frames per second (the rate silent movies were projected). Plus, they have to be shown with the right color temperature light source, the noble gas xenon being preferred. His prints are created and color balanced for specific light sources, and have to be projected by someone capable of handling his prints properly and running this very rare and unique projector.”

As Greené, who moved to Maine last year with his family, explains, it was the prospect of losing out on an equally rare touring retrospective of the California-based Dorsky’s works that sent him on a quest to find someone in Maine who could satisfy all those requirements. “I’m lucky enough to correspond with Nathaniel Dorsky,” says Greené, “and while he was open to the idea of a Maine screening, he said he doubted if anyone in the state had the capabilities to handle his prints.”

Enter Kinonik, the all-celluloid film oasis right here in Portland. “I was jazzed,” enthuses Kelly, recalling his introductory phone call with Greené, the pair bonding over shop talk about everything from xenon vs. tungsten bulbs to rheostat frame rates to voltage regulators and shutter speeds. (As a film geek myself, I could have listened to this sort of thing all day.)

Even for Kinonik, however, “The Arboretum Cycle” presented challenges. Kelly explains how they had a “Canadian film wizard” modify one of their projectors to Dorsky’s exacting specifications, in the process creating what he terms “a one of a kind prototype.” Screening partners The Strand and Portland’s Space (hosting a follow-up screening on May 4) quickly agreed to host both Dorsky’s film and Kinonik’s new equipment, all so viewers can literally watch plants grow.

The two facilitators of this unique screening experience make a compelling case for moviegoers to do just that. Asked about Dorsky’s preference for the beyond-outdated 18fps film speed, Greené says simply, “He loves it. In his book ‘Devotional Cinema,’ Dorsky talks about its connection to the human metabolism, how it creates a deep connection with the body of the audience, from his to theirs. To him, it connects something about being human.”

Kelly, like Greené, eagerly anticipating a first-ever viewing of Dorsky’s two hour-plus film, elaborates on the filmmaker’s documented hiatus from moviemaking, and what brought him back to film “The Arboretum Cycle.”

“Dorsky didn’t make a film for a period of some 12 years. He claims he started to feel a revulsion at the thought of looking through the viewfinder until he had the epiphany that once he could enjoy the physical experience again, that’s what the audience will see as well. These films are about him wanting to be as transparent an observer or conduit as possible. No overexertion or pretentiousness in the filmmaking process, just getting out of your body into a floating sense of awareness and observing the world freely without preconceptions.”

Is that a lot to glean from two hours of light streaming through plants? That’s for adventurous moviegoers to decide. As Benjamin Greené puts it, “I’m thrilled to experience this for the first time. I can’t wait to sit there and have the light pour over us. I may be in the minority of the minority, but I want to see it twice.”

Greené, along with the rest of us, will certainly have that chance, and Nathaniel Dorsky’s “The Arboretum Cycle” will screen at The Strand Theatre in Rockland at 5:30 p.m. Sunday and at Space on May 4, also at 5:30.