The Height Under the Leaves

The first sensor Soren rehung was wrong.

He knew it before Maya said anything, because the little screen blinked red instead of green. Red meant the air was too dry for the row it belonged to. Red meant the storm had knocked the sensor down, and Soren had put it back in a place that only looked right.

Maya crouched beside the boardwalk with her chin almost on the rail.

"Wrong height," she said.

"I used the string. Half a meter."

"Wrong half meter."

Soren looked at the strip of measuring cord in his hand. It had knots tied into it by someone with stronger opinions than handwriting. The storm had tossed orange flags, blue clips, and twelve button-sized sensors across the forest floor. Dr. Lio had pointed at the mess, pushed wet hair out of her eyes, and said, "Sort anything you can without stepping off the boards. I have to get the canopy loggers before they die."

Then she had run toward the tower with a case of batteries banging against her leg.

The station's grown-ups cared about the canopy first. The canopy had orchids and monkeys and towers with lightning rods. The understory had mud, mosquitoes, and two eleven-year-olds who were supposed to keep their boots on wooden planks.

Soren did not mind the planks. Planks made straight lines. Straight lines made it easier to notice when the world refused to use them.

Maya had already stopped looking at the fallen flags. She was looking at a leaf.

"There," she said.

Soren leaned over the rail.

An ant hung beneath the leaf by its jaws. Its legs were curled. A thin brown stalk rose from the back of its head like a tiny, terrible tree. At the tip was a darker knob.

Soren had seen a photo in the field station dining room, under a label that said Ophiocordyceps. Someone had drawn a cartoon ghost beside it, which made the real thing worse.

"Zombie ant fungus," he said.

"Not zombie like movies," Maya said. "Better. Stranger."

Soren took out his notebook, then stopped because the paper was already soft at the corners from humidity. He put it away and counted with his fingers instead.

Leaf underside. Jaw locked on vein. Stalk up. Ant trail below.

A line of living ants moved along a root under the dead one. They touched antennae, passed around a pebble, and continued as if nothing hung above them.

Maya slid sideways along the boardwalk, still crouching. "There is another."

The second dead ant hung beneath a different leaf. Same curled legs. Same bite on the main vein. Same brown stalk.

"Coincidence," Soren said, because one of them had to say it.

Maya pointed without looking back. "Third."

They were not scattered like storm trash. They were arranged in the green shade beside the boardwalk, each one over or near an ant path, each one at nearly the same height above the leaf litter. Not the height of Soren's string. Lower. Damp enough that his knees darkened where the boardwalk had collected rain.

Soren untied the first sensor and brought it down slowly.

"We are not touching the ants," he said.

"Obviously."

"Or breathing on the stalks."

"I am breathing on my own side."

He held the sensor beside the leaf with the dead ant. The screen blinked once, twice, and turned green.

Maya smiled with her mouth closed, which meant she had been right before she had words for it.

"That is not fair," Soren said.

"The fungus tied the knots better."

He checked the screen again. Humid. Cool. Still air. He lifted the sensor toward his original knot on the cord. Red. He lowered it to the dead ant's height. Green.

The forest seemed to tilt.

A minute before, the space beneath the leaves had been messy green air. Now it had layers. Dry above. Splashy below. In the middle, an invisible shelf where a fungus could use an ant to place itself above other ants. Not anywhere. Not almost. Here.

Maya moved to the next support post. "If the storm took the flags, we can use these."

"Use dead ants as flags?"

"Use what happened to them."

Soren looked down the boardwalk. Dr. Lio would not like that sentence. Adults preferred things with serial numbers. But the serial numbers were in a muddy pile, and the ants were still hanging exactly where the storm had not moved them.

He took the measuring cord and made a new knot at the height of the first dead ant. Then he checked the second. Close. The third. Close again. Not perfect, but close in the way living things were close, with tiny differences that still made a shape.

Maya held a blue clip between her teeth and worked the sensor strap around a thin trunk.

"Green?" she asked.

Soren pressed the button. "Green."

They moved along the boardwalk.

At each post, they looked first for ant roads, then for leaves above them. Sometimes there were no dead ants, and Maya would shake her head before Soren even raised the sensor.

"Too open," she said once.

The screen blinked red. Warm and dry.

At the next place, the ground dipped. Soren thought it would be perfect, but the sensor stayed red there too.

"Too wet?" he asked.

Maya touched the rail, then showed him the smear of mud left by last night's flood.

Spores falling into water would not land on marching ants.

He moved the sensor upslope, above a root where living ants funneled into a narrow brown highway. Green.

They found more dead ants there. Some had long stalks. Some had pale fuzz spreading from the joints. One had only clamped jaws and a swollen body, no stalk yet.

Soren backed away from that one.

"It climbed before it died," he said quietly.

Maya did not answer. She watched the living ants below it pour around a seed husk, thousands of legs making one moving line. It waited in falling dust too small to see. An ant touched the wrong speck, carried the forest inside its body, climbed when the colony needed it below, and bit down on the exact vein that held it in place.

Soren had spent the first three days at the station feeling too large and too small at once. Too large when grown-ups squeezed past him on narrow walkways with equipment. Too small when they talked over his head about data gaps and canopy gradients. But down here, the useful map was not on the tower tablet. It was under leaves, at the height where a person had to crouch and be willing to look slightly foolish.

Maya passed him another sensor.

"You are doing the face," she said.

"What face?"

"The one where your head gets too full."

"It is a very full fungus."

"Bad sentence. Good reason."

By the time Dr. Lio returned, splattered with rainwater and carrying a rescued canopy logger against her chest, Maya and Soren had rehung nine sensors. Three fallen ones remained on the boardwalk in a neat row.

Dr. Lio stopped so fast her boots squeaked.

"Please tell me you did not guess."

"We did not guess," Soren said.

Maya pointed beneath the nearest leaf.

Dr. Lio bent, impatient at first, then less impatient. Her eyes moved from the dead ant to the sensor, from the sensor to the trail below, from the trail to the next leaf, and the next.

"You used the cadaver zone," she said.

Maya's eyebrows went up.

"It has a name?"

"Several names," Dr. Lio said. "None of them as useful as this right now."

She took the tablet from her vest. The sensors blinked onto its map one by one, a row of tiny green points curving along the boardwalk instead of marching in a straight line. The curve matched the ants, not the posts.

Dr. Lio made a sound like a laugh that had tripped over a question.

"The old grid was too tidy," she said. "I was measuring the forest as if it were a room."

Maya was already looking past her.

"There are more trails off the boardwalk."

"Yes," Dr. Lio said.

"And more fungi?"

"Yes. Different ants, different fungi, different places. Maybe more than we have names for."

Soren looked at the green points on the tablet. They no longer seemed like dots. They seemed like keyholes.

Dr. Lio held out three clean sensor straps. "I need measurements from the next section. Stay on the boards. Do not touch the cadavers. If a sensor reads wrong, trust the forest before you trust my old knots."

Maya took two straps. Soren took one.

They walked to the place where the boardwalk bent around a buttress root as wide as a wall. The air smelled of wet wood and crushed leaves. Ants moved in a dark ribbon below.

Soren raised the sensor. Red.

Maya lowered his wrist.

Green.

Above the trail, a blank leaf trembled though no rain was falling.

Soren held his breath.

A living ant stepped off the brown highway, placed one foot on the stem, and began to climb.