Holy shit 20 pages, which one of you did the good deed for us to be blessed!?
Yeah I was thinking that too. I would have expected them to be described in the LN as Heart-shaped shrubs, but I have yet to read the LN.Not sure if it's just lost in translation of if it's just the artist making visual pun.
The "Rub Shrub", based on its appearance, should be "Love Shrub" (same kana spelling of ra-bu) with the 'heart' shape it has.