Dropped off of the Mandragoras in East & West Sarutabaruta, the Pygmaiois in Tahrongi Canyon, and Sylvestres in the Buburimu Peninsula.
Like the info says, these are rare/ex, and are involved in a quest in Windurst Walls called "Mandragora-Mad".
If you turn one of these, a 4-Leaf Mandragora Bud, or a Cornette in to Yoran-Oran found - oddly enough - in Yoran-Oran's manor you will be rewarded with a small amount of fame, and some gil.
Perhaps the sulfur does come from Yuhtunga, hence that's why Yoran-Oran is interested in it. I mean, he did say that he wanted to investigate the derivations of this species.