Ask a bunch of kids what constitutes the ultimate tree house, and you’re likely to get some imaginative ideas but few workable concepts. Ask a bunch of architects the same question, and you receive 13 masterfully designed and engineered structures made of steel, wood, bamboo and other materials too grown-up to name.

The latter is just what the organizers of the Dallas Arboretum’s “Ultimate Tree Houses” exhibit did. Opening June 14 and running through December, the exhibit spans the garden’s 66-acre site with conceptually complex and logistically challenging extreme tree houses.

Dave Forehand, Arboretum vice president of gardens, says a similar exhibit 10 years ago served as the model for this event.

“Apparently, it was really popular for a summer exhibit. We can really sense the excitement this year as well,” he says.

A mailer was sent to dozens of local architectural firms with the contest’s basic guidelines: The trees must not be harmed in the process, the tree houses must either be completely ADA accessible or completely inaccessible to everyone, and the tree houses have to be fully awesome.

The organizers received 55 entries, and the field was narrowed down to the 13 most extreme examples.

Forehand says the trees and botanical garden are the palette for these artistic creations, and the challenge brought out the competitive nature of the participants.

“We were amazed by the response and the enthusiasm. It’s some serious detail and engineering.”

Some of the firms submitted entries from multiple teams. Others put together teams with multi-disciplinary skill sets.

The results are intriguing.

“Ultimate Blooms” by the Beck Group lets visitors be the pollinator and move within three massive tulip blooms. The tulips are connected by a wheelchair-accessible ramp and elevated pathways, as well as steps that provide movement between the blooms.

Carter & Burgess’ entry, “Potted Tree,” is just that. The base of the tree appears to emerge from an oversized clay pot. Just a few feet away is a massive watering can, and oversized flowers appear to bloom from the branches above.

Chuck Armstrong, AIA, and Corgan Associates Inc. teamed to build the “Bamboo Basket,” which looks like an inverted tee-pee wrapped around the base of the tree. But this is no low-tech endeavor. The steel superstructure is called a “transegrity frame.” As we said, grown-up stuff.

The “Ultimate Wow,” dreamed up by designer Jay Smith, is described as a “tree-room” and interactive sculpture. But don’t let the fancy description fool you. It has the look of a good old-fashioned backdoor fort.

When asked if he has picked a favorite, Forehand was circumspect.

“I’m still trying to understand them all,” he says.