Herbicide

Oh how what's in a potion matters.... 

Well, this is curiouser than what I had originally thought.

So Herbicide, this is one of the original 9 point potions from the age of Beta. It is still 9 points, and unchanged in points, one of only two potions to make this claim (the other is Polyjuice, and I am not counting part 1 potions here). Currently, it takes a minute and twenty seconds to brew on copper, and like all other potions, is effectively free, as even without collecting ingredients in the story, you can collect the re-collectable galleons and brew from that.

So really, what on earth is special about this potion?

The answer isn't quite as easy to figure out as you'd think. With all potions, there could probably be some logic to ingredients added. Beautification has rose petals, unicorn hair, and cure for boils has sharp-er objects, and the oozy and slimy slug. Doxycide has poisonous ingredients with things such as streelers, and Polyjuice has shedded boomslang skin, fly wings as the flies change quickly from larvae to adult. So there is some precedent, ingredients here serve to play some role, in taking properties from the ingredient into the potion. From this, I'd assume, poisonous ingredient, that could be used for antidotes or for poisons, and other ingredients could "transfer" their properties to the potion as well.

Hi, I'm poisonous!

So then I got to thinking, "well let's see what the apothocary says." Oh how I was surprised. Horklump juice and Lionfish spines are both used for HEALING potions. And both, were what I assume to be things that would otherwise be considered poisonous, due to the venom that lionfish have in their spines, and how Horklumps ruin gardens with their presence according to notes in Fantastic Beasts, and while this fits, it seems sort of odd, that these two, combined with flobberworm mucus, presumably to thicken it up, would work for killing things, when it seems almost more appropriate that it be done to create a salve for healing based off of the material available on Pottermore.

So? What could this mean? Effectively, I'd guess that it presents two things, an opening for an actual healing potion using the same, if not similar ingredients, or a deeper question about potion making, as if the process, in preparing the ingredients, upon different methods may bring out different aspects of the ingredient. Like crushing mistletoe berries as opposed to adding them whole into a potion, or even bringing out aspects like the Prince's book, where some actions bring more of a property out than others. Herbicide is just one potion that shows this, that the uses of ingredients may be able to change based on preparation, and the wizard involved, and brings a whole new level of respect for the art of the potion.