But how trivial was it? The farmers were far too busy addressing the logistics of weightless harvesting to go and plant wheat in the forest just to test an idle conjecture about the effects of companion species on growth rates. No one would have done this unless it was important.
She couldn’t wait two stints.
Weightlessness had transformed the stairwells from sites of interminable drudgery to the mountain’s smoothest thoroughfares. With a pair of ropes all to herself and no one else in sight, Yalda switched to her high-speed gait: propelling herself forward with all four limbs at once, then releasing the ropes and moving ballistically for as long as possible before brushing them again with whichever hands were necessary to correct any sideways drift and replenish her speed. The moss-lit walls flew by, while the threatening edges of the helical groove that wrapped around her, its jagged steps proclaiming a vertiginous descent guaranteed to end with her head split open, only added to her triumphant sense of control. Once you could survive throwing yourself down a staircase as tall as a mountain, anything seemed possible.
Yalda reached the level of the forest in what felt like less than a bell. When she moved from the stairwell to the access tunnels, her mind insisted on treating all the arborine-proof doors along the way as hatches, and she emerged into the chamber with a strong sense of ascending through a floor. The trees stretched out “above” her did their best to persuade her to realign her sense of the vertical, but all the loose detritus suspended around them rather undermined their case.
The refitting of this chamber had been perfunctory, with just a few unpaired guide ropes suspended between hooks on the wall, so Yalda had to push off from the rock and drift freely through the air to enter the forest itself. Once she was among the trees, though, the branches offered plenty of hand-holds. Tiny dark mites darted past her with exuberant energy, coming and going in a flicker. A green-flecked lizard scampered out of her way, its claws still finding easy purchase in the bark. However ancient and unvarying their instincts, these animals had not been defeated by the change.
She found the clearing Fatima had described—and Lavinio with it. He’d crisscrossed the small treeless space with ropes, the better to access the dying wheat plants. Only now did Yalda feel that the netted soil was below her: she was an aerial spy, sneaking through the canopy like the arborine in her grandfather’s story. She descended with as much creaking of branches as possible, to dispel any appearance of furtiveness.
Lavinio watched her in silence as she approached. He looked grimly unsurprised by her presence, as if he’d already faced such a run of bad luck that an unwelcome visitor right in the middle of it was just what he’d expected.
“Can you tell me what this is for?” she asked him, clambering down a trunk then taking hold of one of his ropes.
“I was hoping the wheat might learn from the trees,” he said.
“Learn what?”
“Up.”
Yalda dragged herself nearer. Disconcertingly, the floor of the forest had become vertical to her again, a cave wall from which the trunks around them sprouted like giant, bristling outgrowths. The wheat stalks were aligned with the trees—but presumably they’d been planted that way, so what was there to learn?
“I don’t understand,” she said. “Is something going wrong in the fields?” She gestured at the limp gray wheat-flowers.
“Not like that,” Lavinio replied. “Here, the flowers don’t know when to open; something in the light confuses them. But up in the fields the mature plants are still healthy.”
“That’s good to hear. And the seeds?”
Lavinio reached down into the soil between the stalks and scrabbled around for a while, then pulled out a seed. It must have been put there by hand, in a separate experiment; none of the sickly plants around it could have produced it, let alone possessed the means to embed it in the ground.
Yalda took the seed from Lavinio and examined it carefully. It was covered with dozens of fine white rootlets that had broken through the skin in all directions, favoring no particular side. There was no shoot, though, no beginning of a stalk. The seed did not know which way to grow.
“I thought light and air were the cues for stalk formation,” she said.
“That’s what I was taught. That was the dogma; I never questioned it.” Lavinio took the seed back and turned it between his fingers. “But however shallow the placement… they still don’t seem to find up. Even if half of the seed is uncovered—exposed directly to the light and the air—they don’t get the message.”
Yalda said, “So when the test seeds you sowed in the fields wouldn’t grow, you came down here to see if the forest had a stronger message?”
“That was the idea,” Lavinio said. “With all of this plant material oriented the same way, I was hoping some kind of influence could pass from the trees to the wheat. But the mature wheat just dies here, and the seeds do exactly what they do in the fields.”
Yalda forced herself to remain calm. The mature plants in the fields were still healthy, so the coming harvest wouldn’t be affected; they weren’t facing imminent starvation. But they did not have long to solve this, or there would be no harvest after that.
“What’s happening in the medicinal gardens?” she asked.
“All those shrubs grow from runners, not seeds,” Lavinio replied. “Some of them are sprouting at odd angles, but once the gardeners correct them by hand they’re fine.”
“That’s something.”
Lavinio made a sound of begrudging assent; the disaster was not all-encompassing. But they couldn’t live on holin and analgesics.
Yalda said, “I wish you’d brought this to me sooner.” She could understand him wanting to prove his expertise by dealing with the problem himself, but there was too much at stake for that.
“Frido thought it would be best to find the solution first,” Lavinio explained. “Instead of spreading panic when there was no need.”
Yalda pondered this revelation. Frido knew about the wheat, and he’d kept it from her? Lavinio might have felt that the responsibility for the crops was his alone, but what was Frido’s excuse?
“I’m not interested in spreading panic,” she said. “But we’re going to need as many people thinking about this as possible.”
“I’ve already set up every experiment you could wish for,” Lavinio insisted. “I’m looking at every combination of factors: light, soil, air, neighboring plants… what is there left to test?”
“And nothing appears to be working?”
“Not so far,” Lavinio admitted.
“Then we both know what’s needed,” Yalda said. “The wheat’s been fine until now—and only one thing has changed.”
Lavinio buzzed humorlessly. “So what are we going to do? Fire the engines again, until the next crop is established? And the next one, and the next?”
“Hardly. We’d run out of sunstone in a generation, and then just starve to death a few years later.”
“Then what?” Lavinio demanded. “If only gravity will make the wheat grow—?”
Yalda held up a hand and twirled a finger around. “Spinning creates gravity too. We could put the seeds in a rotating machine—a centrifuge—until they germinate.”
Lavinio considered this. “It’s an idea,” he said. “But what if germination’s not enough? What if it takes half a season under gravity to establish the plant’s growth axis?”
Yalda was reluctant to answer that. The crew was still struggling to adapt to the last change: refitting every apartment, every workshop, every corridor; relearning every daily routine. How much discontent would it foster, to announce that all their efforts had been misdirected, and that everything they’d achieved was about to become obsolete?