THLASPI, in botany, a genus of the tetradynamia filiculosa class. The pod is emarginated, heart-shaped, containing many seeds. There are ten species, six of them natives of Britain, viz. the campestre, or mithridate; the arvense, or treacle-mustard; the perfoliatum, or perfoliate treacle-mustard; the furtum, or perennial mithridate mustard; the montanum, or mountain mithridate-mustard; and the bursa pastoris, or shepherd's purse.