It is not clear why, titled from also unclear Dylan liner notes, A Poem Is a Naked Person waited forty-one years for release. During that time, rumor has it, co-producer Leon Russell gave permission for screenings solely at not-for-profit venues and when accompanied by its director Les Blank. Perhaps that man’s death two years ago has prompted his executive producer son Harrod and Russell to grant the underground legend a SXSW world première, with the musician in attendance, to lead to theatrical release.

On non-profit foundation grants, the filmmaker’s independent Flower Films dealt largely with traditional, or roots, American music types and their cultural milieus. Thus, blues, mountain music, bluegrass, Cajun, Creole, Tex-Mex, Scotch-Irish, Hawaiian, Polish-German polka, frequently though not always in rural settings among plain folks.

Done over two years, this eighty-nine minutes enters the world of the raspy singer-pianist less generally known for his own music than as one of the industry’s sought-after super session men, arrangers and producers. Most of the handheld footage captures Russell and his backup sidemen and -women instrumentalists and singers and buddies at his Grand Lake of the Cherokees Shelter Records studio compound outside Tulsa nearly on the Missouri line. Longhair bearded hippie types in the Ozarks Heartland, they interact with and are accepted by locals, kids who groove, hunters, farmers, fishermen, country kibitzers, city slickers, and an elderly lady who finds her husband sexier now that he, too, foregoes barbering.

A Tulsa concert with his band, as well as snips of other performances, is inserted here and there, with de rigueur ecstatic audience faces and close-ups of singers’ mouths about to gobble mics. There is a cut of a studio “Take Me” with George Jones and a “Good-Hearted Woman” by a near unrecognizable pre-beard Willie Nelson. But, as with many such films, numbers are not included in their entirety but only enough to be frustrating, with the more extended sets as liable to be instrumental, though the banjo picking is impressive.

Except for Russell at the piano for Mendelssohn at an eclectic psychedelic flower-child wedding in a columned mansion, complete with an unnecessary little girl cringe-inducing a lengthy Hoyt Axton’s “Joy to the World/Jeremiah Was a Bullfrog,” much of the sound is generically C&W, albeit with a call-and-response churchly flavor -- awkwardly underlined by a black service and preacher -- and, to lefty Russell’s Jerry Lee Lewis piano pounding, a decided blues-gospel slant. What music and fire would have sparked from a pairing of him and Janis Joplin!

In certain asides and images, PINP recalls Jazz on a Summer’s Day, both outside “rockumentary,” both caressing faces not only at the venues but also in the host towns, and both seeking the social and natural environment, as for instance water patterns in ripples in a lowering sun.

Photographer Bert Stern’s sole motion picture, however, does not truncate its performers in embracing, in addition to jazz, blues, gospel and R&R and in this is superior, a unique music documentary. In contrast, Blank dissipates much of the energy in, devotes too much of his screen time to local color, loungers, parachutists and glass-eaters, building demolitions, country stores, scorpions, snakes and chicks, high school marching bands, tractors pulling dozens of men, and a swimming pool. There is sometimes dark humor from the subjects -- “You’re in good hands with Allsnake” -- and a fair-to-middling amount of half-baked spoken pseudo-philosophy that, although not a word is breathed of preferred illegal substances of that era, makes sense only after weed at the very least.

The film comes close to sinking itself with excess ethnography at the expense of the subject, which after all is music, within a context but still sounds. Russell himself concludes with his compulsion for music as expression, and, when everything is sung and done, what we want is music, music, music.

(Released by Janus Films; not rated by MPAA.)