Everything felt wrong as Jenkins's organs started to churn before slowing to an odd, queezy stillness. The doctor had felt nauseous, sweaty, and on the verge of wetting his pants just seconds earlier, but all of that was over now. His internal anatomy had already become simpler and more uniform, and was yet to become even moreso, but there was no way he could have known this. Jenkins just felt odd.
After several seconds of trying to figure out why he still felt the same except for his inner oddness, Jenkins began to moan as a green coil started to unroll from his abdomen into a long stalk with with a shrinking green curl at the end. As it unfurled before him, he noticed a wispy green feathering that was thick and leaf-like near the base. Exhausted after forcing out this new growth in front of him, Jenkins took deep breaths, feeling his new frond wobbling in front of him. Bewildered, he reached out to touch it. Whatever it was supposed to be, it was still part of him--the manly fumbling of his large hands over its complex, branching structure pinched his leaflets and sent twinges of discomfort back into him through the lengthy central stalk.
"Ow!" Jenkins let go of his broad, fanning appendage and watched it dangle in front of his belly. As he stared in anxious wonder, he realized that he could feel some other kind of feeling flowing deeply into himself from within it. It was a pleasant and strangely familiar sort of ... refreshment? He couldn't quite understand it yet.
Before the man could reflect any further on his inhuman attachment and the medley of sensations it gave him, the human majority of his body clinched up again as he felt burgeoning new pressures on his chest, his shoulders, and his back. Even his feet were starting to weaken and stretched out, forcing him to practically roll sideways onto the ground, careful not to topple forward onto his leafy green appendage. Distressingly, he could see what looked like duplicates sprouting in front of him, unfurling from the new fiddleheads sprouting enthusiastically from his chest. This time, when it was over, the disgraced doctor could feel that his breathing was much slower, the sensation of catching his breath washing over him not just from his lungs, but also from the undersides of his wobbly new fronds. His dazzling plant-like additions weren't just parasitic attachments to his body. At some invisible, microscopic level, these things were breathing for him, or rather he was breathing through them. If he sprouted many more of these things, he wouldn't need his lungs at all.
"I'm turning into a plant," he said weakly, valiantly voicing the realization that had finally constructed itself within his addled mind. How could this be? His meagerly funded research unit had only achieved a serum and partial antidote for horse transformations! Sure, he knew they were probably using variations for other mammals in other departments, and there were theoretically possible serums for bird and lizard transformations, and maybe even insects. But PLANTS?! Someone had already generalized all of the animal-specific assumptions of his formula and invented a serum for turning humans into PLANTS?
'Perhaps I wasn't as intellectually indispensable to The Zoo as I thought,' Jenkins dejectedly realized, looking over his fern-like torso and the rough, hairy-looking rhizome his legs had merged to become. Another wave of change hit him, and he grew an additional batch of new fronds as his arms shrank back closer into his body. Spindly wires of root tissue advanced in all directions from his shrinking rhizome as the change continued. The rhizome tissue crept up, overtaking more of his abdomen, becoming a proper base for his ominous green fronds. Jenkins was getting almost of all of his oxygen from his leaves now as his diaphragm slowed to a stop. His last few organs were starting to dissolve themselves into the plant tissue his torso was becoming. His heartbeat was barely detectable anymore. He couldn't speak. He could see and hear, but he wasn't sure how much longer it would be until his face was absorbed into the fern he was becoming.
The two men who had injected him came back up and picked Jenkins up to carry him out from the shed. It was a lot warmer and brighter out in the large open area of the greenhouse. The warm touch of the light and humidity on his leafy tissues felt ... intoxicating! Every square millimeter of green chlorophyll tingled with energy and satisfaction. It was like the peace of digesting a large meal--not in his stomach, but in a dozen blades on a dozen stalks, basking in the sunlight filtering in through translucent walls. Jenkins's eyes rolled back in his head, and he almost allowed himself accept his predicament, basking in the pleasure of his leaves' first exposure to sun.
"Well, doctor," said one of the men as the two lowered him down into a large pot. "As you can see, you have been reassigned to a new position at the greenhouse, probably for the rest of your career. Over here, we don't have to worry about our transfers escaping, or usurping human leaders of the department."
More curly fiddleheads emerged from his body and sprouted up into fully grown fronds, bringing Jenkins even more of the raw carnal pleasure he was discovering as they spread themselves wide under the sunlight. His eyes darkened, his ears shrank back into the rhizome his original body had become, and Jenkins was left in silent darkness, with nothing to feel but the overwhelming ecstasy of his own photosynthesis and the nagging fear and anger that his human life was over with no reentry and no fanfare. There was nothing left for Jenkins but to ... oh ... live out his life as a ... oh ... fern, which ... OH! ... might not be so bad...
As Jenkins was soaking up the sun and air around him, he felt dirt and soil getting piled up around him, with his fronds still sticking out of it. The greenhouse workers were planting him! He felt a thirst welling up inside his tangle of roots, as they quickly went through what little moisture was in the dusty old potting soil. That was soon remedied when drenching torrent of water jostled the soil and dissolved it into heavy black sludge. Then it was over, and Jenkins was left there as a freshly potted fern, with nothing to do but try to make the most of his new life as a plant.