In the middle of a cloud forest that receives 100 inches of precipitation a year, Karen Masters hikes with a spray bottle each day to mist the orchids.

Only half of the orchid ecologist's 155 tagged flowers receives the puff of mist, however. The rest are left to struggle through the Monteverde dry seasons, which have been worsening since the 1970s. Copious rain still falls behind the Monteverde Biological Station where Masters teaches, but the frequency of fine mist that falls through the two-to-three month dry season is declining. Will orchids decline as well?

To show the One World Journeys team her experiment, the 40-year-old scientist leads downhill to one site and then uphill to another, our cadence called by hummingbirds chirping for mates. She takes a bridge across a narrow ravine where a stream sluices down, darts past gigantic tropical sweet cedar and oak, and ducks under a log. At a sun-dappled place where a fallen giant has opened a hole to the sky, she clambers over broken deadfall to her flowers.

Masters is a woman with the energetic quickness of a bird, a smile bright and broad as the tropic moon, and the passion to bear witness. In 1985 she photographed the golden toad; the film was misplaced, and the toad soon after went extinct.

"That really is horrible," she laments. "I never thought when I took those pictures that the toads wouldn't come back. I took them for granted."

Now, she fears, the same could happen to her flowers.

The orchid she studies, Pleurothallis segovienses, is a wad of green leaves not much bigger than a quarter, not yet in flower. It dries out quickly in the unceasing trade winds and, like most of the cloud forest's 500 other identified species of orchid, is dependent on silvery mist to keep itself alive.

Each year, the mist seems lighter. "It's worrisome," Masters confides. "Monteverde is the epicenter of orchid diversity. We live here, and we've seen things change. It seems wet, but it's getting drier."

To test her hypothesis that orchids are in danger, she's tagged those growing on fallen trees. The branches are so heavily coated with epiphytes, or plants that grow on other plants, that all the leaves on one toppled giant are in fact squatters of other species, including orchids. Most orchids here live high in the forest canopy, never touching the ground.

She sprays half her samples to mimic the 1970s climate here and leaves the other half alone. Her goal is to demonstrate that the decline in mist could doom the flowers.

Why study such modestly miniature orchids? "The littlest ones are the cutest," she contends, pointing out the erotic curves and variegated colors of even the smallest flowers. "The other reason is that they seem to be very vulnerable to climate extremes." The little ones don't have the "pseudo bulbs" of larger orchids that store water like a camel's hump.

Orchids are one of the most varied of all flowering plants, with 20,000 species. Some are perfumed, some stink, some are pale, and some are flush with color. Each has evolved to attract a particular pollinating insect or bird. Their odd shapes welcome some pollinators and deter others.

Fruiting orchids can spew millions of tiny seeds. They provide nectar and food; they also help cycle nutrients for other plants. Some orchids lure male insects with an oil that makes them attractive to females.

Kill the orchid through global warming, and an entire ecology begins to unravel.

The same could happen to the bryophytes, mosses, ferns, and other plants that festoon the branches of Monteverde's trees. Some live in close relationship to their host, straining the air of its nutritious mist and creating soil a hundred feet off the ground.

Masters mists her plants with real mist - atmospheric fog and fine rain caught in mist collectors - because the mist droplets form around particles of atmospheric dust that carry nutrients and pollution to the forest. It makes her experiment realistic.

Her work can seem puzzling on a wet day, however. When she explained to visiting scientists that her contraptions were "collecting the mist," a colleague squinted into the miserable drizzle and grumped, "Well, young lady, you're not doing your job."

Through her experiments, college teaching, conservation volunteer work, and board membership at her twin sons' environmentally-based school, Masters does what she can to protect a cloud forest she first came to in 1984. She can't save it alone, however.

"Most of what determines if the cloud forest lives is going to happen in the industrialized countries," she tells us. "We have to stop putting carbon dioxide into the atmosphere. Unfortunately, that's hard medicine to swallow. We live in a consumption-oriented society. Here in Monteverde we see many, many, many subtle environmental changes. But too often, even those who do see what's happening don't do anything about it."