I don't know if someone has posted these (SPCV Memebers may not like to read this!)
3 Black Orchids - Yikes! (Lowers health a lot!)
2 Cactus + 1 Black Orchid - That Potion was Awful (Makes Sick)
It seems each plant has certain properties i.e Tiger Lilly for fun/happiness, Cactus for health and Black Orchid for sickness/weakness.
Hey I'm SPCV president and I try out all potions, even if they might be bad. Just sayin.