pestilence weed

Webster's Dictionary (GCIDE)

1.Specifically, the disease known as the plague; hence, any contagious or infectious epidemic disease that is virulent and devastating. [1913 Webster]

The pestilence that walketh in darkness.— Ps. xci. 6.[1913 Webster]

2.Fig.: That which is pestilent, noxious, or pernicious to the moral character of great numbers. [1913 Webster]

I'll pour this pestilence into his ear.— Shak.[1913 Webster]

Pestilence weed (Bot.), the butterbur coltsfoot (Petasites vulgaris), so called because formerly considered a remedy for the plague. --Dr. Prior. [1913 Webster]