This morning there was a post on one of the bushcraft/foraging/backpacking Facebook groups I'm in, warning members against using the group as a plant verification service, because someone had misidentified poison hemlock (are there other kinds of hemlock?) as yarrow.
I'm bad at plants, so for the most part I don't even try to pretend I can ID anything than isn't poison oak, coast live oak, fennel, or madrone. But like, given how similar hemlock and yarrow look, how good do you think Sam and Dean are at plants? Especially since half the time they're looking at dried-up plants outside the context of like, natural range, because they've been stuffed in some drawer for a decade. And they'd have to be good at plants across the country (including invasive species, or old-school plants that might not even exist in that form anymore), not just a particular region that they inhabit. I mean, they're probably really good at plants. Though if you're using them for magical purposes, I imagine there are just as many spells that work famously with similar substitutions as there are spells that call for exactly this strain of plant, harvested in exactly this season. (Rowena seems like the kind of person who'd be interested in exploring possible substitutions and pushing magic to its horizons rather than getting overly caught up in previously-established exactitudes, though obviously she's also interested in the masterworks of witches you've come before her. But to be a really good witch, I'll bet you have to develop your own iconic practices, ingredients, spellwork variations.)
Plus, like, when do Sam and Dean have time to refresh and add to their encyclopedic knowledge of weirdness (both monsters and all the related accoutrements, like plants)? Sam's active interest in ancient languages is apparently pretty recent, because he went from being derisive about ancient Greek in late S7 to being able to like, aurally ID some kind of ancient church dialect in early S12. So most of what he learned (outside of Church Latin) is a recent acquisition! Though he's always been observant about plants, and able to offer their botanical historiography on the fly. :P
And like, they have strengths that complement each other astonishingly well, because Dean has a photographic memory for sigils (though even into mid-S4, he still could not remember all the words to a demonic exorcism, lol. i feel u, Dean, though maybe paste that one by the bathroom mirror and force that memory as hard as it will go?? XD). And he apparently knows what casting a Chinese throat-binding spell looks like. (Since I'm 100% certain Dean has never actually cast such a spell himself: Did he find an illustrated guide? Has anyone ever been able to make heads or tails of guides like that?)
The history of dance notation is long and storied and before the advent of video, largely unsuccessful. So can you imagine what attempts at gestural spells/ceremonies would look like, for the archives? Obviously the tradition would have to have been on more of an apprenticeship model than an academic/book-y one, but then the Men of Letters established themselves, and I can only imagine they could have tried their very hardest to come up with a spellwork notation (and maybe this was the root cause of the schism between hunters and MoL, whereas in earlier years/pre-widespread literacy specialization would have been less of a thing??).
Really I think what I want is a choose-your-own casefic where you have to try to solve puzzles to advance your reading, and the whole thing is like the end of the first Harry Potter book, with the chess and the potions and whatnot--except with Sam and Dean.