Well, you can probably guess my opinion of plant-based SCPs in general. ;) As for specific comments:
1) Spores are not unique to fungi. Ferns and mosses both use them for primary propagation.
2) You repeatedly describe this thing modifying host tissue & chemistry to its tastes. How is it doing that without triggering nasty, nasty immune responses? All else being equal, the host body would treat the plant as an invader and ramp up defenses, rendering the host desperately ill. There are plenty of real-world parasites that (at least try to) get around these defenses; maybe I'm just an incorrigible geek, but I'd like to hear how this one does it. Or even just that it doesn't, and you've got horrid Spanish-flu symptoms to deal with on top of the parasite itself. (Actually, that's even worse… eeehh.)
3) I might like this better if it didn't take over the body entirely. We have an awful lot of life-usurping parasitic SCPs, and the idea of someone whose lungs have been converted to insect traps trying to live normally creeps me out more than Yet Another Shambling Horror. (YASH? Hm. Acronym.) The distension of the chest and stomach, the hijacking of lung tissue, the slow repurposing of your body to something else's specifications, would be worse (in my eyes) if you were quite aware of it, and it wasn't fatal…
