The Collaborative International Dictionary of English v.0.48:

Coltsfoot \Colts"foot`\, n. (Bot.)
   A perennial herb (Tussilago Farfara), whose leaves and
   rootstock are sometimes employed in medicine.
   [1913 Webster]

   Butterbur coltsfoot (Bot.), a European plant (Petasites
      vulgaris).
      [1913 Webster]

The Collaborative International Dictionary of English v.0.48:

Pestilence \Pes"ti*lence\, n. [F. pestilence, L. pestilentia.
   See Pestilent.]
   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]

The Collaborative International Dictionary of English v.0.48:

Butterbur \But"ter*bur`\, n. (Bot.)
   A broad-leaved plant (Petasites vulgaris) of the Composite
   family, said to have been used in England for wrapping up
   pats of butter.
   [1913 Webster]

WordNet (r) 3.0 (2006):

Petasites vulgaris
    n 1: small Eurasian herb having broad leaves and lilac-pink
         rayless flowers; found in moist areas [syn: butterbur,
         bog rhubarb, Petasites hybridus, Petasites vulgaris]