When the University of Hawai'i announced just over a week ago that its 194-acre arboretum deep in Manoa Valley would be closed to the public indefinitely because of safety concerns, it meant a scramble for teachers at Kokohead Elementary who had assembled children from four schools for a field trip a few days later.

It meant the same for Laughlin, who is now canceling 22 field trips by O'ahu schools through the middle of November, forcing teachers to rearrange curriculum, buses and even lunchroom plans.

The indefinite closure also has raised a number of other concerns, from the future of facilities for critical research on endangered and rare native plants, to the loss of dozens of educational classes enjoyed by the public, to questions about whether the popular annual plant sale will continue.

While the immediate fate of the arboretum and its research projects is still unknown, university administrators say that they expect all of the cottages on the property — used for everything from offices to labs — to fail safety inspections being completed this week Should that happen, a critical micropropagation laboratory that's growing rare and endangered native plants will have to be moved to the Manoa campus.

"We're making plans for the eventuality of being told to close all those cottages," said Jim Gaines, interim vice president for research, who headed the university's investigation of the situation. "We're going to provide another space for that (the micropropagation lab) and all other endangered collections. But even moving those plants raises the danger level for them."

With four cottages already closed, staff offices will be moved to what is now the visitor center.

Estimates of repairs or renovations are running as high as $3 million over two years, said Gaines, but so far the university doesn't know if cottages could be repaired or should be torn down.

No one is saying how long the arboretum will stay closed, but Gaines said it will reopen "only when we have addressed these health and safety issues."

Current thinking calls for canceling the kava festival planned for October and the annual plant sale in November. But if adequate toilet facilities could be installed temporarily, those two events could possibly take place, said Gaines. Those decisions will be up to Manoa chancellor Peter Englert, he said.

At present, only staff are allowed on the premises; even the army of volunteers who help maintain collections and act as tour guides are banned.

Some staff said they feel the closure is unwarranted, a retaliation for their complaints about poor management, and an over-reaction to structural problems.

"They could rope off areas that are questionable and still people could wander around and have a wonderful time here," said long-time employee Ray Baker, a research associate chiefly responsible for creating a world-class palm collection, with more than 600 species. "In my opinion, this is retaliation for us going over their heads to the Board of Regents (with complaints about safety and management practices.)"

But the university said it is worried about liability and the staff's safety. Inspections have shown crumbling timbers in the cottages and uncovered wiring. There are also trails that are potentially dangerous, although Gaines said he believes those could be made safe in a matter of days.

"No one is talking about staff losing anything," said Gaines. "It's their health and safety that's of prime concern, in addition to the children of the state. The retaliation component is zero."

State auditor Marion Higa is expected to soon issue a report on operations at the arboretum.

Every year, more than 4,000 students traipse through the magical depths of the arboretum, learning about taro, ginger, palms and indigenous Hawaiian plants.

"It's a dagger in my heart to think Lyon Arboretum has closed their services," said Janice Nishiki, a second-grade teacher at Noelani School who has taken students to the arboretum on field trips for more than a decade and who helped create a summer science program.

"First-graders go there and look at plants from the tops to the bottoms," said Nishiki. "They measure tree trunks and weather conditions. They eat by the lily ponds and write haiku. They weed and plant and dig in the garden. And the shama thrush, a beautiful bird, comes and sits with them when he sees them digging."

To teach children, said Nishiki, "you have to go out and see it. We can't do it just with textbooks."

In one of the few cottages momentarily deemed safe for use, Nellie Sugii said she just won't leave her plants.

As manager of the micropropagation lab, Sugii is the one in charge of taking rare and endangered native Hawaiian plants and reproducing them in temperature- and light-controlled test-tubes, to build up populations of plants for return to the wild.

Scientists at Lyon have created a unique repository of rare and endangered Hawaiian plants, with Sugii's team propagating at least half of the 100 plants in the state's Genetic Safety Net program and Alvin Yoshinaga's seed conservation lab putting into cold storage seeds from more than 300 rare, indigenous plants.

Sugii's lab contracts with both the State Department of Land and Natural Resources and the U.S. Army to propagate rare — or even extinct — native plants for return to the wild.

"This is a huge linchpin in our conservation efforts," said state botanist Vickie Caraway. "Probably this is the only place in the U.S. doing this work to the level that Lyon is.

"There are plants that are extinct in the wild that are in that lab," said Caraway. "So it's of huge concern to us. One of the focal points of our whole program is to make sure we maintain that store between the seed lab and the micropropagation lab."

Several months ago, when Sugii's research cottage was lifted for repairs, about half of the 38,000 plants she's been working with were lost, or went back to landowners because they couldn't be cared for properly. "What really concerns me if I have to move, what will it do to my cultures again?" Sugii said.

For Bruce Koebele, with the Cultural Learning Center at Ka'ala in Wai'anae, Sugii's work is helping restore native plants to the back of the valley, where hundreds of children are learning about their Native Hawaiian heritage.

"We want to show them what their ancestors would have seen 500 years ago," said Koebele, "and how their ancestors used it."

The thousands of plants growing within the arboretum are themselves "a living collection that's being added to all the time" and it's imperative to keep that collection going, said David Orr, botanical programs coordinator of the Waimea Valley Audubon Center.

"It's the major repository in Hawai'i for most of the world's heliconia," he said. And the palm collection is considered one of the world's best, if not the best.

"There is such wealth there," said Orr, "not just for Hawai'i, but for the whole world."