Late summer afternoon sunlight lances through the canopy of a tall tupelo poplar, which together with an equally massive tulip tree forms the core of the Out on a Limb exhibit at Morris Arboretum & Gardens, a dizzying 50 feet above the forest floor.

Nests of thick rope netting are attached around the tree trunks, with a triangle of wide metal grating walkway around the periphery like a high-wire platform.

Lying flat on their backs on brightly colored mats along the walkway, others flopped out in the netting like incredibly relaxed fish, everyone’s eyes are closed. The only sounds are the chirps and chitters of birdsong in the leafy green canopy.

That, and the soothing voice of Maura Manzo, yoga instructor, leading the group of about 30 women and men – mostly women – in guided mediation.

It’s all a gentle prelude to an evening of Yoga in the Treetops, held at the arboretum one Thursday a month from April through October. As yoga sessions go, this one has to be among the most unusual.

It’s an evening of easy, and perhaps not so easy, stretches, moving from one choreographed yoga position to the next. Downward dog, child, prayer, plank, tabletop, pigeon, happy baby, cobra, warrior, and – appropriately – the stork-like tree pose, one foot raised to rest against the opposite knee, arms upraised.

The entire session lasted about 90 minutes. Manzo closed it out more or less as it began, with students stretched out around the platform and in the netting. Manzo read from David George Haskell’s “The Songs of the Trees.” And with that, the session was over. Just watching it was an exercise in tranquility.

Colette Batog, who travels from Birdsboro, Berks County, describes the treetop session as “a very different experience. It’s nice to do yoga outside.”

Batog was one of the students who nestled in the rope nets. She said it was like being on the trampoline between the twin hulls of a catamaran.

Mark Monaghan, retired and a member of the arboretum, is another fan of treetop yoga. He is a student of Maura Manzo at her studio, Camaraderie, in Ambler. It was his first time attending the class.

“Ambler is right around the corner from us,” he says. “I go [to the studio] five to 10 times a month, but this is a very different experience – very much. And I will come back. I want to get here in October. We have to register for that. I bet it’ll get crowded because it’ll be gorgeous here.”

Like Batog, Monaghan spent some time in the net – in his case, face down. “It was really cool,” he says. “I had a kind of existential experience. All of a sudden, I started to notice how high up I was, but I wasn’t afraid. It was a little weird because I’m afraid of heights, but it felt safe.”

Mary Campbell, of Chestnut Hill, has attended treetop yoga on several occasions. “I teach yoga with Maura, and I was introduced to it last year,” she says, “ and how could it be less spectacular than this? It’s just magic. It just puts you in the zone.”

Manzo has been teaching for close to 20 years, the treetop exercise for the past four. She is as entranced by the location as her students are.

“What’s different about this class as opposed to outdoor yoga in general is that this exhibit gives us a really steady foundation,” she says. “We don’t have to worry about being on the ground or roots or bugs or things like that. We trust the exhibit. We feel safe up here. We can take in the trees, the light, the sounds. But especially as the class goes on, for the people who come every time or even a couple of times a season, they get to see the changes that happen. The changes in the leaves, the changes in the light. They get to just really experience the elements and their breath with the elements in a different way.”

To register, visit the arboretum website at morrisarboretum.org. The class is $35 for members; $40 for non-members, Pricing is per session. The class begins at 5:15 p.m. The next class is Aug. 27.