Mandragora

Mandragoras are a type of plant youkai. Although they resemble turnips or radishes, they belong to the nightshade family and hate being compared to any plants outside of it. They're foul mouthed and like saying mean things, but can be nice to people who tend to them or call them the right species of plant.

Hyakki Academy's Biology Club (consisting of Maizuka Mamekichi and Abe Haruaki) grows them on the school's rooftop garden, and there are over 300 of them as of chapter 56. Though they all look the same, Haruaki has named all of them and can tell them apart.