It is a bizarre prokaryotic flowering plant parasite which has graphene reinforced cell walls and is so distinct from all other organisms to warrant placement in its own domain of life (indeed it only showed up less than a million years ago).
Infects both a variety of sufficiently large flowering plants and vertebrates (granting psychic abilities, which aren't relevant here in the latter case). Spreads throughout plant hosts, penetrating their cells to siphon resources and hijacking their gene expression to help itself reproduce. This entails keeping the plant from growing old or flowering naturally, so it can live indefinitely and use all its energy growing and producing galls to spread the parasite:
The first kind of gall has the host grow a bunch of leaves, fruit/seeds, and flower petals in a bizarre randomly generated fractal pattern. The galls' fractal patterns are always unique, but often have similarities to Romanesco broccoli. Regardless of host plant this gall will lack any toxins normally produced to deter herbivores, usually being fully edible. This attracts pollinators/herbivores, who will contact the black fuzz on the gall and end up spreading its spores. Black fuzz has some superficial resemblance to down feathers, but grows in a dendritic fractal pattern. Since these galls frequently contain various flower anatomy they can often serve to propagate the host plant. Of course even when galls can reproduce they are less effective than the plants own natural flowers.
The second type of galls produced somewhat resemble a traditional plant gall, but are hollow and their inside covered in black fuzz (to attract and infect small nesting birds). These second galls are much less common and don't use anywhere near as much of the hosts resources.
Notably while the "black fuzz" which covers the edible galls can be eaten, thorough washing is needed to remove the spores which are a potent psychedelic.
How would pre-modern agricultural output (and consequently population) be impacted by this parasite, which can make most flowering plants produce edible galls?
This parasite requires exposure to psychic abilities to produce viable spores so it very rarely spreads on its own. However, deliberately farming the parasite is extremely easy given every community will have psychics
Knowledge of animal/plant breeding is far more advanced for the tech level in this scenario. So assume people have access to all forms of pre-modern traditional agriculture.
Part of series with: Just How Omnipresent Would Cheap Cross Laminated Spider Silk Be?
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