This was a supreme specimen amongst magic plants. It contained a truly terrifying amount of mana inside it to the point that when enough were gathered mana would start condense and become viable to the naked eye, almost like a group of fluttering pixies, hence the name of the flower.
The use of such a powerful plant couldn't be underestimated. It was mostly used in powerful potions reserved for 1st class fighters and mages, even some potions for master class level combatants still used this magical plant so even for a place as wealthy as the sites where you can plant the pixie's tear lily were of keen interest.
In fact, If it wasn't for the fact these plants needed to be grown out in the wild combined with the fact it was a good experience for new students in Sanctuary, they would grow internally and closely monitored.