The Collaborative International Dictionary of English v.0.48:

Throatwort \Throat"wort`\, n. (Bot.)
   A plant (Campanula Trachelium) formerly considered a remedy
   for sore throats because of its throat-shaped corolla.
   [1913 Webster]

WordNet (r) 3.0 (2006):

throatwort
    n 1: European bellflower with blue-purple to lilac flowers
         formerly used to treat sore throat [syn: throatwort,
         nettle-leaved bellflower, Campanula trachelium]