The Japanese Wikipedia of To LOVE-Ru mentions two out of many types of plants:
I tried looking in the manga of both the original and sequel To LOVE-Ru Darkness but I can't find it.
What chapter/episode each one of those plants was in?
The Hore Herb (ホレ草) is inferred in To LOVE-Ru volume 5 chapter 40 and the Horedan Flower (ホレダンの花) is from an original scenario on a booklet packaged with The First Edition of To LOVE-Ru Darkness 2nd BD/DVD.
In volume 5 chapter 40 of To LOVE-Ru (凶悪バレンタイン, A Brutal Valentine' Day),
when Rito asked Mikado-sensei what happened to the students, she replied that she had told Lala to add an aphrodisiac from a plant from Planet Hore in her chocolate.
御門: 催淫効果のあるホレ星の薬草を入れるように教えちゃったのよね
(The original panel in Japanese)
Regarding The First Edition of To LOVE-Ru Darkness 2nd BD/DVD, this is the booklet.
However, there's no review/further information about the content of the booklet, aside from the Japanese Wikipedia putting a footnote for the source of Horedan Flower.
