LONGWOOD Gardens has long been known for its pristine topiaries, gorgeous greenhouses, incredible lawns and generally flawless flora.

But for several weeks, Pierre S. du Pont's vast and elegant onetime country estate has gleaned international attention for its lush, planted . . . potties.

The 1,077-acre site's 4-year-old facilities are among 10 nationwide finalists in an online contest to be crowned (throned?) "America's Best Restroom."

It's no wonder Longwood's loveliest loos caught the eyes of competition organizer Cintas, a Cincinnati-based uniform, restroom and restaurant mega-supplier/cleaner. The lavs, located within the serene East Conservatory, reside behind silver doors that line a long, curved hallway. Each of the 17 stalls is spacious, spa-like and, according to State College's Janet Bamat, who recently paid them a brief visit, "spaceship"-like, too.

The plumbed pods are private and kidney-shaped, with red sinks, domed skylights and modern, hands-free fixtures. An orchid plant adorns each water closet. Fiberglass Eames chairs and scooped-out diaper-changing areas outfit three extra-large family facilities.

Each unit is air-conditioned in summer and hydroponically heated (from floor up) in winter. And each virtually soundproof stall is big enough that, said Elissa Hart, a volunteer assigned to talk with guests about the area, "You could have a party in there."

Hold it.

These toilets have tour guides?

Yup.

It's a standing joke for Longwood director Paul Redman. He said, "When I'm speaking around the world, I say these are probably the only restroom facilities in the world that have a team of highly trained expert docents."

Potty mouths

The helpers aren't there to assist in hand-washing, much less the final step in guests' digestion. They're there to discuss the washrooms' hallway. Growing out from the 4,072-square-foot wall around and above the stall doors are 47,000 ferns and other verdure.

Longwood's facilities are more than facilities. They're North America's largest green wall.

Acclaimed British landscape architect Kim Wilkie designed the soaring, sunlit space. Plants sprout from a vast grid of 1-by-1-foot vertical trays connected to an invisible irrigation system that sends off mist similar to that in a supermarket's produce section. Every few feet, a small paper bag that dangles from a stem imperceptibly releases tiny mites to control pests that would otherwise devour leaves and flowers.

But those are the details.

The effect is what's stunning.

"I'm totally surprised by this," said visitor Jon Clark, of Horsham. "I hate to use it as a restroom."

"It's a beautiful greenway," said Barbara Haedrich, a longtime Longwood member who owns a nearby B&B. "I refer to it as 'Bathroom Boulevard.' "

Indeed, the erstwhile privy is one of the gardens' most popular spots for engagement and wedding pics, along with endless selfies.

The restroom area "definitely has become a destination here for more than one reason," said Redman.

Question is, how do these toilets stack up to their swirl of competition?

So far, fellow flushing front runners include:

* Bowl Plaza, a mosaic-adorned building shaped like a toilet in tiny, folk-artsy Lucas, Kansas, currently in second place.

* The Byzantine-style, circa 1929 Fabulous Fox Theater, in St. Louis.

* Retro Fort Lauderdale restaurant Mai-Kai, a self-proclaimed "Grand Polynesian Palace of Tiki."

Bowl Plaza has walls containing cemented-in Matchbox cars and Barbie dolls, and a sidewalk that resembles unrolling toilet tissue. Mai-Kai has mirrors on its ceilings and gilt fixtures throughout. The Fox Theater is currently hosting "Dirty Dancing the Musical."

The other erstwhile outhouses are impressive, for sure. Lucky for us, as of yesterday contest reps said that our Longwood's entrants are aimed at number one.

Fingers (legs?) crossed. After all, in a toilet competition, it's no fun being No. 2.

Voting at Bestrestroom.com ends Friday.

On Twitter: @LaMcCutch